This chapter offers technical information needed to address the design, installation, operation, maintenance, and inspection of event recording devices at locations with interconnected highway-rail grade crossing signal systems.

3.1 Technical Information

This section describes the functional requirements for event recording devices to be installed at highway-rail grade crossing locations with highway traffic signal preemption. The intent of these devices is to provide operating and maintaining agencies with a tool to assist them in ensuring that interconnected signal systems are working as designed. These devices can be installed as standalone units or integrated with other devices installed in a highway traffic signal controller cabinet or railroad grade crossing equipment bungalow. The functional requirements of three different potential interconnected system configurations are discussed in this section, and are classified as "new", "hybrid", and "legacy" systems. The new configuration refers to new or future systems with interfacing capabilities between highway and railroad signal controllers using IEEE Standard 1570 (8). A hybrid configuration refers to existing systems having some level of event recording and/or processing capabilities. The legacy configuration refers to existing systems having no event recording or processing capabilities. For the highway components of these systems, the minimum requirements should be supported by all types of highway traffic signal control architectures and assembly types.

Minimum required events and alarms are proposed for each system configuration. For each proposed event and alarm, there is a description of the event or alarm and an explanation of how it can be monitored and recorded. For new and hybrid system configurations utilizing IEEE Standard 1570, these explanations include how the events and alarms can be generated from the information included in the defined IEEE Standard 1570 messages. For the hybrid and legacy systems that will not be utilizing the IEEE Standard 1570, the explanations include how the events and alarms can be generated from the various equipment and circuits input to the event recorder.

3.1.1 New Systems

"New" systems have the capability to interface between the highway traffic signal controller and railroad grade crossing controller using IEEE Standard 1570. IEEE Standard 1570 uses a serial communication interface between the highway and railroad systems to communicate vital safety-critical system information such as preemption requests and health status, as well as additional information and data used to monitor each system. IEEE Standard 1570 is explained in further detail in a subsequent section (see "IEEE Standard 1570").

There are currently only a few existing highway traffic signal controllers that provide even a limited amount of support for IEEE Standard 1570. These controllers use IEEE Standard 1570 as another means of providing the preemption input and only support the two safety-critical IEEE Standard 1570 messages, which are subsequently described in detail. At present, there are no highway traffic signal controllers capable of using the additional IEEE Standard 1570 railroad messages (other than preemption information) to modify the preemption sequence in the traffic controller. Highway agencies and/or traffic signal equipment manufacturers will need to develop this functionality in the future. The additional information provided via the IEEE Standard 1570 messages will still be a useful maintenance tool for highway agencies and railroads through monitoring and event recording.

The supervisory component of the interconnected interface should be performed using the defined IEEE Standard 1570 messages over the serial communication interface. This system should meet the Federal requirements for processor-based signal and train control systems defined in 49 CFR 236 Subpart H (see "49 CFR 236 Subpart H Requirements").

Figure 3 shows a functional block diagram of a typical new system configuration.

IEEE Standard 1570

This section provides an explanation of the IEEE Standard 1570, the IEEE standard for the interface between the rail subsystem and the highway subsystem at a Highway Railroad Intersection (HRI). The following summarizes the content of the IEEE Standard 1570, including the necessary components and the messages the standard defines in detail.

The IEEE 1570 standard defines the Advanced Transportation Controller (ATC) as the platform that provides the digital data communication link at the highway traffic signal control cabinet. The term "ATC" refers to a specific controller standard that is a product of a national standards development effort comprised of the Institute of Transportation Engineers (ITE), American Association of State Highway and Transportation Officials (AASHTO), and the National Electrical Manufacturers Association (NEMA). This standard is still being developed with the latest version 06.05, which is pending approval as of this writing. There are several other enhanced controller platforms currently available on the market that are in use by agencies and could support the IEEE 1570 standard. For this reason, the generic term "traffic controller" is being used in this report so as to not preclude the use of alternative traffic signal controller platforms that an agency may want to use to support the IEEE 1570 communications standard in a future deployment.

The primary purpose of an interconnection interface between the highway and railroad controllers at a HRI is to preempt highway traffic signal operation in order to clear traffic from the crossing as a train approaches. Existing standards define analog interfaces, generally using an electrical cable to convey voltage between the two subsystems, where the absence of voltage on the wires results in the highway traffic signal entering preemption operation. As required by Federal regulations, this existing interface is designed to meet both fail-safe and closed loop principles.

IEEE Standard 1570 specifies a digital communications interface between the highway and railroad subsystems that provides equivalent functions and maintains the safety requirements of existing systems. In addition to providing the preemption functions currently carried out by an interconnection circuit, this interface specifies digital data communications to provide for the sharing of additional information between the highway and railroad subsystems. This standard also supports future upgrades in equipment functionality on both sides of the system, but it does not mandate that functionality.

Figure 3: New System Configuration Functional Block Diagram

The IEEE Standard 1570 interface uses a digital serial connection between the highway advanced transportation controller (ATC) and the railroad wayside equipment terminator. Both the ATC and the wayside equipment terminator handle numerous control functions, which typically reside in separate physical devices and communicate via an internal communications network. IEEE Standard 1570 does not make assumptions about the technology used to implement those control functions. The standard only specifies the interface between highway and railroad subsystems and not the interfaces internal to the highway or railroad subsystems. In other words, this interface provides a means for control functions in the ATC and the wayside equipment terminator to communicate with one another without specifying the internal communication structure in either system. This allows for flexibility in the actual allocation of components and supports alternative equipment placement should it be necessary in the future.

The HRI interface consists of a virtual or logical component and a physical component. The virtual component is what provides the channel for communication between the ATCs and the wayside equipment terminator. It consists of the message formats and information content that flow between the two systems. The physical component of the interface is the physical connection that facilitates the transfer of data between the highway and railroad internal data networks, acting as a bridge between the two independent components.

The HRI interface architecture is made up of four functional components: ATC functions, ATC gateway, wayside functions, and wayside gateway. Figure 4 shows the HRI interface and the functional components of the HRI interface architecture, which are described following the figure.

The ATC functions are those functions internal to the ATC that obtain or generate the information to be transmitted to the railroad system across the HRI interface. They also process data received from the railroad system.

The ATC gateway acts as the internal router and interface bridge controller for the ATC. It is responsible for interfacing with the internal ATC functions and routing incoming or outgoing messages across the HRI interface to the wayside gateway or to the appropriate ATC function.

The wayside functions are those functions internal to the wayside equipment terminator that obtain or generate the information to be transmitted to the highway system across the HRI interface. They also process data received from the highway system.

The wayside gateway acts as the internal router and interface bridge controller; for the wayside equipment terminator. It is responsible for interfacing with the internal wayside functions and routing incoming or outgoing messages across the HRI interface to the ATC gateway or to the appropriate wayside function.

More than one type of protocol is specified for the HRI interface. This gives equipment manufacturers flexibility to implement the HRI interface to fit an installation's specific circumstances. The data link and physical layer protocols provide the physical infrastructure for the HRI physical interface. The protocols specified for these layers include Ethernet, RS232, RS422, and RS485. These protocols should support the transfer of individual message packets of up to 128 bytes in length at a minimum of 19.2 kilobytes per second, meaning the protocols should be capable of transferring a 128 byte message packet across the HRI interface in less than 250 milliseconds.

Figure 4: HRI Interface

HRI Messages

IEEE Standard 1570 defines a total of 12 messages for exchange over the HRI interfaces, which are listed in Table 6.

This section, which addresses the required minimum amount of information to be shared between the highway and railroad subsystems, describes how four of the eight defined messages should be used to transfer information to the event recorder in system configurations using the IEEE Standard 1570 protocol for communication. A description of each of the four messages recommended for use is provided with an explanation of the standard information included in each message packet.

The same standard data format is used for all defined HRI messages. The information in this standard data format includes the message length, a time stamp (date and time, from the month down to the second), a message sequence number, a message label, and a message version number. Also included is information identifying the message as vital or non-vital and the actual message data.

Table 6: HRI Messages

MESSAGE ID	MESSAGE NAME	SOURCE	DESTINATION	SAFETY-CRITICAL?
9.4.40	HRI Rail Crossing Operational State	Railroad	Highway	Yes
9.4.41	HRI Approaching Train Information	Railroad	Highway	No
9.1.41	HRI Approaching Train Information Request	Railroad	Highway	No
9.4.42*	HRI Wayside Equipment Status	Railroad	Highway	No
9.1.42*	HRI Wayside Equipment Status Request	Highway	Railroad	No
9.4.43	HRI Roadway Obstacle Detection State	Highway	Railroad	Yes
9.4.44*	HRI ATC Equipment Status	Highway	Railroad	No
9.1.44*	HRI ATC Equipment Status Request	Highway	Railroad	No
9.4.45	HRI User-Specific Wayside Message	Railroad	Highway	No
9.1.45	HRI User-Specific Wayside Message Request	Highway	Railroad	No
9.4.46	HRI User-Specific ATC Message	Highway	Railroad	No
9.1.46	HRI User-Specific ATC Message Request	Railroad	Highway	No

*Reserved for future use

HRI Rail Crossing Operational State (9.4.40)

This message is transmitted from the railroad system to the highway system and is defined as a safety-critical message. The message is sent at a frequency of once per second, and is called the vital heartbeat message from the wayside system. Byte 0 of the message data includes a field named RHBA, for receiving vital heartbeat (9.4.43) from the ATC system. The status of this field will be either '0' for "Not Receiving Message 9.4.43" or '1' for "Receiving Message 9.4.43". The definition of receiving or not receiving is determined locally and should be defined by the equipment manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the ATC system, as well as the highway system's receipt of the wayside vital heartbeat message within the specified allowable time, represents the vitality of the HRI interface.

Also included in byte 0 of the message data is the number of crossings. The standard is defined for 1 to 8 crossings, each of which may contain from 1 to 8 tracks and up to a maximum of 8 trains associated with each crossing. The overall message length is dependent on the number of crossings and the number of trains associated with each of those crossings. Bytes 1 through 7 are repeated for each crossing, and bytes 5 through 7 are repeated for each train associated with each of the crossings. Other fields defined in this message include:

• Crossing sequence number
• Number of trains associated with this crossing
• System Operational (SO)
• Train Presence Detection (TPD)
• Warning System Active (WSA)
• Preemption Warning Active (PEA)
• Exit Gate Present (XGP)
• Exit Gate Up (XGU)
• Exit Gate Down (XGD)
• Entrance Gate Present (NGP)
• Entrance Gate Up (NGU)
• Entrance Gate Down (NGD)
• Preemption Design Time
• Train Sequence Number
• Direction (DIR) - Direction of the train
• Island Occupied (ICO)
• Warning System Activation Design Time
• Estimated Time to Warning System Activation

Note that not all of these fields are required for use as outlined in this section.

HRI Roadway Obstacle Detection State (9.4.43)

This message is transmitted from the roadway system to the railroad system and is defined as a safety-critical message. The message is sent at a frequency of once per second, and is called the vital heartbeat message from the ATC system. Byte 0 of the message data includes a field named RHBW, for receiving vital heartbeat (9.4.40) from the wayside system. The status of this field will be either '0' for "Not Receiving Message 9.4.40" or '1' for "Receiving Message 9.4.40". The definition of receiving or not receiving is determined locally and should be defined by the equipment manufacturers or the highway agency and railroad. Receipt of the vital heartbeat message from the wayside system, as well as the railroad system's receipt of the ATC vital heartbeat message within the specified allowable time, represents the vitality of the HRI interface.

This message also provides safety-critical crossing obstacle information to the railroad system. The information fields defined in the message include:

• Vehicle present with gate down (VP)
• Long term obstacle indicator (LTI)
• Vehicle arrestor barrier status (VAS)
• Roadway system operational (RSO)

It is noted that the standard is not intended to define the functionality of obstacle detection; it is only intended to provide a framework for transferring such information to the railroad system should any obstacle detection exist. The specific functionality should be agreed upon by the highway agency and railroad. Obstacle detection functionality is not required for event recording as defined in this section.

HRI User-Specific Wayside Message (9.4.45)

This message is transmitted from the railroad system to the highway system and can be defined as either an informational message or as a safety-critical message. The highway agency and railroad should jointly determine the message definition. Transmission of the message can be defined as either on request or on a periodic basis. Therefore, the message frequency should also be determined and agreed upon by the highway agency and railroad. If the message is sent upon request, the defined HRI User-Specific Wayside Message Request (9.1.45) will be used. This is a one byte query message sent from the ATC system to the wayside system to request that the wayside system send the HRI User-Specific Wayside Message (9.4.45).

The data content and format of the user-specific message should be defined by the highway agency and railroad. Additionally, the highway agency and/or railroad should specify data fields in this message to include the following information:

• Lock out protection
• Power (On/Off)
• Entrance alarm (Open/Closed)

This message data is required in order to monitor and record several of the events described in "Events". The highway and railroad equipment used to communicate these messages, as well as the event recording devices used to monitor these messages, should be programmed to support the user-specific message settings.

HRI User-Specific ATC Message (9.4.46)

This message is transmitted from the highway system to the railroad system and can be defined as either an informational message or as a safety-critical message. The highway agency and railroad should jointly determine the message definition. Transmission of the message can be defined as either on request or on a periodic basis. Therefore, the message frequency should also be determined and agreed upon by the highway agency and railroad. If the message is sent upon request, the defined HRI User-Specific ATC Message Request (9.1.46) will be used. This is a one byte query message sent from the wayside system to the ATC system to request that the ATC system send the HRI User-Specific ATC Message (9.4.46).

The data content and format of the user-specific message should be defined by the highway agency and railroad. Additionally, the highway agency and/or railroad should specify data fields in this message to include the following information:

• Preempt in (Field termination)
• Preempt in (Traffic controller input)
• Vehicle and pedestrian signal circuits
• Signal/Flash
• Cabinet electrical service
• Main cabinet door status

This message data is required in order to monitor and record several of the events described in "Events". The highway and railroad equipment used to communicate these messages, as well as the event recording devices used to monitor these messages, should be programmed to support the user-specific message settings.

49 CFR 236 Subpart H Requirements

The primary purpose of the safety-critical interconnection interface between the highway and railroad systems of a highway-rail grade crossing is to preempt highway traffic signal operation in order to clear traffic from the crossing as a train approaches. As required by Federal regulations, this existing interface is designed to meet both fail-safe and closed loop principles. Section 8C.09 of the MUTCD specifies, "This preemption feature shall have an electrical circuit of the closed-circuit principle, or a supervised communication circuit between the control circuits of the highway-rail grade crossing warning system and the traffic control signal controller." Part 16.30.10 of the AREMA C&S Manual (9) states that, "The interconnection between the traffic control signal and the railroad warning system shall be a double break relay circuit or serial data circuit in accordance with IEEE Standard 1570-2002." New systems should also provide fail-safe supervision of the vital preemption functions to be carried out using the serial communication interface specified in IEEE Standard 1570. 49 CFR 234.275 states that, "Highway-rail grade crossing warning systems, subsystems, or components that are processor-based and that are first placed into service after June 6, 2005, which contain new or novel technology, or which provide safety-critical data to a railroad signal or train control system that is governed by part 236, subpart H or I, of this chapter, shall also comply with those requirements. New or novel technology refers to a technology not previously recognized for use as of March 7, 2005."

New systems using the IEEE Standard 1570 interconnection interface between the highway and railroad systems are subject to the requirements of 49 CFR 236 Subpart H. 49 CFR 236 Subpart H specifies the minimum performance standards for safety-critical products. This includes the requirements railroads are subject to for development, installation, implementation, inspection, testing, operation, maintenance, repair, and modification of safety-critical products. Additionally, 49 CFR 236 Subpart H contains a detailed explanation of the required filing and approval processes for Railroad Safety Program Plans (RSPPs) and Product Safety Plans (PSPs). It also specifies product implementation procedures, operation requirements, testing and records recording requirements for safety-critical products, and the requirements of training and qualification programs for these products. Supervisory components and acceptable message frequencies of the IEEE Standard 1570 communication interface should be specified in the RSPP and PSP.

Each railroad subject to this subpart must submit a RSPP to the FRA for approval. The RSPP is the principal safety document for all safety-critical products and it must establish the minimum PSP requirements that will govern the development and implementations of the safety-critical products. These plans must include complete descriptions of the preliminary safety analysis, including the methods used to evaluate a system's behavioral characteristics, the risk assessment procedures, the system safety precedence followed, and identification of the safety assessment process. A RSPP also requires identification of verification and validation methods, including the standards to be used in this process. Finally, the RSPP requires a description of the process used to identify human factors issues and development of design requirements to address those issues, as well as to specify requirements for product configuration management. Railroads should consult 49 CFR 236.905 for a complete description of the contents required in a RSPP.

Railroads must also submit a PSP for each new product subject to 49 CFR 236 Subpart H. The PSP must provide complete descriptions of the product and all of its components, the railroad operation(s) it is intended for, the product operational concepts, and safety requirements. The PSP also must include all safety assessment, verification and validation processes and the associated results, a hazard mitigation analysis, a risk assessment, description of the safety assurance concepts, and a human factors analysis. Complete descriptions of the specific training for railroad employees and contractors and of the specific procedures and test equipment needed to ensure safe and proper installation, implementation, operation, maintenance, repair, inspection, testing, and modification are also required to be included in a PSP. Among several other requirements, a PSP must also include, for each of the requirements of 49 CFR 234, an explanation of how the product meets the requirement, why the requirement is not applicable to the product design, or how the new product satisfies the requirement using alternative methods. Railroads should consult 49 CFR 236.907 for a complete description of the contents required in a PSP.

As stated in 49 CFR 236.909, the minimum performance standard for products covered by this subpart is that, "The safety analysis included in the railroad's PSP must establish with a high degree of confidence that introduction of the product will not result in risk that exceeds the previous condition. The railroad shall determine, prior to filing its petition for approval or informational filing, that this standard has been met and shall make available the necessary analyses and documentation as provided in this subpart." This section also explains the requirements for full and abbreviated risk assessments that must be completed to support the minimum performance standard.

Full risk assessments are required to address the safety factors associated with the introduction, modification, replacement, or enhancement of safety-critical products. This includes any risks from the previous condition that are no longer present as a result of the new product or change, new risks associated with the changed or new product, and risks that are not affected. 49 CFR 236 Appendix B contains the specific requirements of a full risk assessment. An abbreviated risk assessment may be submitted instead of a full risk assessment if there are no new hazards introduced as result of the change, and there is not an increase in hazard severity or exposure from the previous condition. Railroads should consult 49 CFR 236.909 for specific requirements of an abbreviated risk assessment to support the minimum performance standard.

Event Recording

New system configurations should include an event recording device to monitor the communication between the highway and railroad systems. The recording device(s) should be connected to the communication interface between the ATC gateway in the highway traffic signal controller cabinet and the wayside gateway in the railroad grade crossing equipment bungalow, and should monitor the messages sent between the two systems. Event recorders installed should be able to process the IEEE Standard 1570 messages in order to monitor the status of the various highway traffic signal and railroad grade crossing subsystems and record the required events, as necessary. The proposed minimum required events to record are listed below with a general description and an explanation of the associated IEEE Standard 1570 message and message field that contains the information required for a recorded event.

Highway Events

1. Roadway System Operational
   The health of the highway traffic signal system should be monitored using message 9.4.43. In this message, the Roadway System Operational (RSO) field represents an overall health check to show that the highway system is operational. This message should be monitored for a change in status between "System Operational" and "System Not Operational". In the occurrence that the highway system is not operational, an event record should be created and an alarm reported.

2. Preempt In
   This should record the change in state of preemption controller input based on the MUTCD standard hierarchy (drawbridge, railroad, emergency, transit). Specific to rail operation, there should be one input for each rail preemption circuit entering the highway traffic signal controller cabinet.
   
   Field Termination should record the first electrical termination in the highway traffic signal controller cabinet from the rail control circuit. A change in status at the first electrical termination in the highway traffic signal controller cabinet should be recorded as an event. This will identify if an active preemption call was received by the highway traffic signal controller cabinet assembly from the railroad control system. The status of the preemption field termination should be included in message 9.4.46 as defined by the highway agency. Traffic Controller Input should record the electrical termination in the highway traffic signal controller cabinet as it provides the preemption input to the highway traffic signal controller. A change in status of the preemption input into the highway traffic signal controller should be recorded as an event. This will identify if an active preemption call was properly routed through interface circuitry to initiate a valid preemption sequence. The status of the preemption traffic controller input should be included in message 9.4.46 as defined by the highway agency.

3. Vehicle/Pedestrian Signal
   This should record phases, overlaps, and displays for vehicle and pedestrian signals. Circuit status should be provided at the termination point used for connecting the highway traffic signal control system with vehicle and pedestrian signal displays ("green", "walk", etc.). This information should be logged for a time period of at least 60 seconds, but not less than the highway traffic signal cycle length, prior to a rail preemption call and for an equal time period after the call for rail preemption is terminated. The status of the vehicle/pedestrian signals should be included in message 9.4.46 as defined by the highway agency.

4. Right-of-Way Transfer Time
   This should record the status of the right-of-way transfer time in the highway traffic signal preemption sequence. The right-of-way transfer time is the amount of time needed for the highway traffic signal equipment to react to a preemption call plus any green, yellow, red, pedestrian walk, and pedestrian clearance time prior to the track clearance green interval. The status of the right-of-way transfer time (when it commences and terminates) should be included in message 9.4.46 as defined by the highway agency.

5. Track Clearance Green Interval
   This should record the status of the track clearance green interval in the highway traffic signal preemption sequence. The track clearance green interval is the portion of the highway traffic signal sequence after completion of the right-of-way transfer time when the green signal indications are displayed to roadway users in order to vacate the highway-rail grade crossing based on the minimum track clearance distance. The status of the track clearance green interval (when it commences and terminates) should be included in message 9.4.46 as defined by the highway agency.

6. Flash Operation
   This should distinguish between conditions upon which an intersection operates in flash mode: conflict monitor trigger, manual switch trigger, or time of day programming trigger. In conflict monitor or manual switch mode, the highway traffic signal controller cannot initiate the preemption sequence. In time of day mode, the highway traffic signal controller can initiate the preemption sequence. The input provided from the highway traffic signal controller cabinet electrical bus connected to flash transfer relays should be monitored and a change in status should be recorded as an event. The status information for flash operation should be included in message 9.4.46 as defined by the highway agency.

7. Cabinet Electrical Service
   This requires monitoring for deviations in electrical service voltages that would trigger the conflict monitor/malfunction management unit. Any deviation in the electrical service triggering the conflict monitor/malfunction management unit as defined by the highway agency should be recorded as an event. This serves to identify the stability of electrical service. This information for the highway traffic signal controller cabinet electrical service should be included in message 9.4.46 as defined by the highway agency.

8. Main Cabinet Door (Open/Closed)
   This requires monitoring of highway traffic signal controller cabinet access, prompting further examination of the various devices and data programming to determine if changes have been made. This is particularly beneficial if the highway traffic signal controller cabinet has been accessed in between inspections. The input should be provided through an appropriate electrical switch connected to the main cabinet door that detects a change in status between when the door is opened or closed. A change in status between "Open" and "Closed" should create an event record and an alarm reported. The status information for main cabinet door should be included in message 9.4.46 as defined by the highway agency.

Railroad Events

1. Supervisory Circuit
   The vitality of the highway-rail grade crossing preemption circuit should be supervised by monitoring the status of the receiving vital heartbeat fields in messages 9.4.40 and 9.4.43, which are each sent once per second between the ATC and wayside systems.
   
   The RHBA field in the message 9.4.40 indicates if the wayside system is receiving the vital heartbeat (9.4.43) from the ATC system. This message should be monitored for a change in status between "Receiving Message 9.4.43" and "Not Receiving Message 9.4.43".
   
   The RHBW field in message 9.4.43 indicates if the ATC system is receiving the vital heartbeat (9.4.40) from the wayside system.
   
   This message should be monitored for a change in status between "Receiving Message 9.4.40" and "Not Receiving Message 9.4.40".
   
   In the occurrence that one of these messages is not received within a certain time interval as determined by the highway agency and railroad and a change in status occurs, an event record should be created and an alarm reported. This supervisory component of the system should meet the requirements of 49 CFR 236 Subpart H (see "49 CFR 236 Subpart H Requirements").
2. Railroad System Operational
   The health of the railroad grade crossing warning system should be monitored using message (9.4.40). In this message, the System Operational (SO) field represents an overall health check to show that the railroad system is operational. This message should be monitored for a change in status between "System Operational" and "System Not Operational". In the occurrence that the railroad system is not operational, an event record should be created and an alarm reported.
3. Railroad Preemption Request
   The preemption request from the wayside system to the ATC system is contained in message 9.4.40. The Preemption Warning Active (PEA) field(s) of the message should be monitored for a change in status between "Active" and "Not Active". A change in status of this field should be recorded as an event. This recorded event serves to identify when an active railroad preemption call was placed.
4. Approach Circuits
   Train presence detection (TPD) information for each crossing track is contained in message 9.4.40. The TPD field(s) of the message should be monitored for each track crossing included in the message. A change in status between "Train Present" and "No Train Present" should be recorded as an event. This recorded event serves to identify when a train has been detected on an approach of any of the crossing tracks.
5. Railroad Crossing Relay
   The railroad crossing relay (XR) controls when the active grade crossing warning systems are operational. For newer systems, the grade crossing controller processors carry out the function of the railroad crossing relay by assigning variables in a logical expression to set the status of the grade crossing warning system. The status information of the grade crossing warning system is contained in message 9.4.40. The Warning System Active (WSA) field(s) should be monitored for a change in status between "Activated" and "Not Activated". This recorded event serves to identify when the railroad grade crossing warning system is in an operational state (e.g., lights flashing, bells ringing).
6. Entrance Gate Status
   Entrance gate status information is contained in message 9.4.40. The Entrance Gate Present (NGP) field of the message indicates if entrance gates are present at the crossing and can either have a status of "Entrance Gate(s) Present" or "Entrance Gate(s) Not Present". In the occurrence that there is a change in status, an event record should be created and an alarm reported.
   The Entrance Gate Up (NGU) and Entrance Gate Down (NGD) fields should be monitored for a change in status. For the NGU field, a change in status between "Entrance Gate(s) Up" and "Entrance Gate(s) Not Up" should be recorded as an event. For the NGD field, a change in status between "Entrance Gate(s) Down" and "Entrance Gate(s) Not Down" should be recorded as an event.
7. Exit Gate Status (if present)
   Exit gate status information is contained in message 9.4.40. The Exit Gate Present (XGP) field of the message indicates if exit gates are present at the crossing and can either have a status of "Exit Gate(s) Present" or "Exit Gate(s) Not Present". In the occurrence that there is a change in status, an event record should be created and an alarm reported.
   
   The Exit Gate Up (XGU) and Exit Gate Down (XGD) fields should be monitored for a change in status. For the XGU field, a change in status between "Exit Gate(s) Up" and "Exit Gate(s) Not Up" should be recorded as an event. For the XGD field, a change in status between "Exit Gate(s) Down" and "Exit Gate(s) Not Down" should be recorded as an event.
8. Island Circuit Occupancy
   Island circuit occupancy information for each crossing track is contained in message 9.4.40. The Island Occupied (ICO) field(s) of the message should be monitored for each track crossing included in the message. A change in status between "Island Circuit Occupied" and "Island Circuit Unoccupied" should be recorded as an event.
9. Train Direction
   Traditionally, the direction of a train movement is determined by the status of the directional stick relays on each track. For newer systems, the railroad grade crossing controller processors carry out the function of the directional stick relays by assigning them as variables in a logical expression relating train presence detection on the approach and island circuits to the train's direction. Once a train has been detected on an approach circuit and an island circuit consecutively, the train's direction is determined and the appropriate directional stick variable is set to indicate the direction of the train's movement.
   
   The directional information of each train movement is contained in the Direction (DIR) field(s) of message 9.4.40. A change in status between "Unknown", "Heading East/North" and "Heading West/South" should be recorded as an event. A status of "Unknown" is the default when there is no current train movement. The directional designations do not indicate the geographical direction of movement, but refer to the directional designation for the track as defined on the railroad's track plans.
10. Lock Out Protection
    Lock out protection should be provided for each train movement through a highway-rail grade crossing. After a train movement has completed, if the trailing circuit does not clear after a preset time interval, an event should be created and an alarm reported. This information should be included in message 9.4.45 defined by the operating railroad.
11. Power (On/Off)
    This requires the electrical power source for the railroad grade crossing equipment bungalow to be monitored. The power off relay (POR) switches the power source that feeds the bungalow. When there is a loss of power, the POR drops to switch to the battery power supply. A change in status of the power off relay (when it drops or picks up) should be recorded as an event and an alarm reported. Additionally, any changes in voltages that would result in an alarm being reported, as determined by the operating railroad, should create an event record. This information should be included in message 9.4.45 as defined by the operating railroad.
12. Entrance Alarm (Open/Closed)
    This requires the bungalow door switch to be monitored for a change in status between "Open" and "Closed". A change in status should create an event record and an alarm reported. This may require the installation of an electrical switch in existing railroad grade crossing equipment bungalows that changes state when the door is opened and closed. This event record would allow the railroad to determine when the bungalow has been accessed, flagging the potential necessity for further examination of various devices and programming. The status of the bungalow door should be included in message 9.4.45 as defined by the operating railroad.

Figure 5 illustrates the sequence of railroad events to be recorded for each train movement through the highway-rail grade crossing.

Figure 5: Railroad Events to be Recorded for each Train Movement

Alarm Reporting

In addition to monitoring the IEEE Standard 1570 messages and recording the required events, the device should be able to process this information in order to flag recorded events and/or report alarms. Event recorders should use user-specific logical expressions to relate fields of various IEEE Standard 1570 messages to determine that the highway and railroad systems are working as designed. As defined by the highway agency and/or railroad, any recorded event or logical combination of events should be flagged as an alarm. A list of situations that should result in the reporting of an alarm along with explanations of how they can be determined is provided below. At a minimum, flagging event records will allow highway agency and/or railroad personnel to determine if a problem exists at a crossing during regular maintenance or inspections.

The following is a list of proposed situations for which an alarm should be reported. These alarms should be determined by monitoring the recorded events or IEEE Standard 1570 messages previously described. Event recorders should be capable of processing and relating the fields of each recorded event or IEEE Standard 1570 message described in order to trigger the alarm(s).

1. Event records indicate that the vital heartbeat message from the ATC system is not being received by the wayside system or the vital heartbeat message from the wayside system is not being received by the ATC system. This should be determined by monitoring the RHBA field of message 9.4.40 and the RHBW field of message 9.4.43. If the status of the RHBA or RHBW fields changes from '1' to '0', indicating one of the vital heartbeat messages has not been received by the opposite system, then an alarm should be reported.
2. Event records indicate that the highway or railroad system is not operational. This should be determined by monitoring the SO field in message 9.4.40 and the RSO field in message 9.4.43. If the status of the SO or RSO fields changes from '1' to '0', indicating one of the systems is not operational, then an alarm should be reported.
3. Event records indicate that the railroad preemption request is not being sent prior to the design preemption warning time. The preemption warning time provided for a particular train movement should be determined using the recorded time stamps of message 9.4.40 for when the status of the PEA field(s) changes from '0' to '1' (preemption warning is active) and when the status of the ICO field(s) changes from '0' to '1' (island circuit or the crossing is occupied). If the preemption warning time provided is less than the time specified in the Preemption Design Time field of message 9.4.40, then an alarm should be reported.
4. Event records indicate that a train is being detected on an approach circuit and the associated island circuit; however, there is no recorded event for a railroad preemption request. This is determined by comparing the TPD, ICO, and PEA fields of message 9.4.40. If the status of the TPD and ICO fields changes from '0' to '1' (train has been detected on an approach and associated island circuit) and the PEA field remains at '0' (preemption was not requested), then an alarm should be reported.
5. Event records indicate that the highway traffic signal controller did not receive or did not act on the receipt of a preemption request. This is determined by comparing the PEA field of message 9.4.40 and the Preempt In (Field Termination/Traffic Controller Input) fields in message 9.4.46. If the status of the PEA field changes from '0' to '1' (railroad system has requested preemption), but the status of the Preempt In (Field Termination) field does not indicate receipt of the preempt request or the status of the Preempt In (Traffic Controller Input) does not indicate a valid preemption call into the highway traffic signal controller, then an alarm should be reported.
6. Event records indicate that the grade crossing warning system is not being activated before the specified warning time. The warning time provided for a particular train movement should be determined using the recorded time stamps of message 9.4.40 when the status of the WSA field(s) changes from '0' to '1' (warning system is active) and when the status of the ICO field(s) changes from '0' to '1' (island circuit or crossing is occupied). If the warning time provided is less than the time specified in the Warning System Activation Design Time field of message 9.4.40, then an alarm should be reported. 49 CFR 234.225 requires activation of the grade crossing warning system to occur at least 20 seconds prior to a train occupying the highway-rail grade crossing.
7. Event records indicate that the entrance gate(s) begins to descend prior to the required minimum of three seconds after the grade crossing warning system is activated and the flashing lights begin to operate (49 CFR 234.223). This should be determined by comparing the recorded time stamps of message 9.4.40 when the status of the NGU and WSA fields change. If the status of the NGU field changes from '1' to '0' (entrance gate(s) is no longer up) less than three seconds after the WSA field changes from '0' to '1' (warning system is active), then an alarm should be reported.
8. Event records indicate that the entrance gate(s) reach horizontal position after the required minimum of five seconds prior to a train arriving at the highway-rail grade crossing. This should be determined by comparing the recorded time stamps of message 9.4.40 when the status of the NGD and ICO fields change. If the status of the ICO field changes from '0' to '1' (island circuit or crossing is occupied) less than five seconds after the NGD field changes from '0' to '1' (entrance gate(s) is down), then an alarm should be reported.
9. Event records indicate that the exit gate(s) begins to descend prior to the completion of the track clearance green interval, potentially trapping vehicles within the highway-rail grade crossing. This should be determined by comparing the XGU field of message 9.4.40 and the track clearance green interval status in message 9.4.46. If the XGU field changes from '1' to '0' (exit gate(s) is no longer up) before an indication that the track clearance green interval has terminated, then an alarm should be reported.
10. Event records indicate that an entrance or exit gates(s) has left the vertical position but there is no recorded event indicating the gate(s) has reached the horizontal position within a preset time interval. This should be determined by comparing the recorded time stamps of message 9.4.40 when the status of the entrance or exit gate(s) up and down fields change. If the status of either the NGU or XGU fields change from '1' to '0' (entrance or exit gate(s) have left the vertical position) and there is no recorded event showing the status of the respective NGD or XGD fields changing from '0' to '1' before a present time interval, then an alarm should be reported.
    
    Alternately, event records indicate that an entrance or exit gate(s) has left the horizontal position but there is no recorded event indicating the gate(s) has reached the vertical position within a preset time interval. If the status of either the NGD or XGD fields change from '1' to '0'(entrance or exit gate(s) have left the horizontal position) and there is no recorded event showing the status of the respective NGU or XGU fields changing from '0' to '1' before a present time interval, then an alarm should be reported. Part 3.3.30 of the AREMA Communications & Signals Manual of Recommended Practice (C&S Manual) states that gate arms should fully raise in no more than 12 seconds, or as instructed.
    
    Finally, event records indicate that an entrance or exit gate(s) is in both the vertical and horizontal position in the same message. If the status of the NGU or XGU is '1' (entrance or exit gate(s) is in the vertical position) and the status of the NGD or XGD is '1' (entrance or exit gate(s) is also in the horizontal position), then an error has occurred and an alarm should be reported.
11. Event records indicate that the right-of-way transfer time is longer than the design right-of-way transfer time. This should be determined by comparing the recorded time stamps of message 9.4.46 when the status of the right-of-way transfer time indicates it commences and terminates. If the right-of-way transfer time is longer that the design maximum right-of-way transfer time, then an error has occurred and alarm should be reported.
12. Event records indicate that the track clearance green interval is less than the design track clearance green interval. This should be determined by comparing the recorded time stamps of message 9.4.46 when the status of the track clearance green interval indicates it commences and terminates. If the track clearance green interval is less than the design track clearance green interval, then an error has occurred and an alarm should be reported.
13. Event records indicate that the amount of time from the start of the track clearance green interval to train presence detection on an island circuit is less than the design track clearance green interval. This should be determined by comparing the recorded time stamps of message 9.4.46 when the status of track clearance green interval indicates it commences and of message 9.4.40 when the status of the ICO field changes to '1' (island circuit is occupied). If the time between the start of track clearance green and island circuit occupancy is less than the design track clearance green interval, then an error has occurred and an alarm should be reported.
14. Event records indicate train presence detection on an island circuit, but there is no event record indicating the termination of the track clearance green interval. This should be determined by comparing the status of the ICO field of message 9.4.40 and the status of the track clearance green interval field of message 9.4.46. If the status of the ICO field is '1' (island circuit is occupied) before an indication that the track clearance green interval has terminated, then an error has occurred and an alarm should be reported.
15. Event records indicate train presence detection on an approach and an island circuit, but does not indicate the train direction; or event records indicate a train direction when no train was detected, signifying a possible electrical problem with the circuits or relays. This should be determined by comparing the status of the TPD, ICO, and DIR fields of message 9.4.40. If the status of the TPD field is '1' (train is present on an approach or island circuit), the status of the ICO field is '1' (respective island circuit is occupied), and the status of the DIR field is '2' (train direction is unknown), then an alarm should be reported. Alternatively, if the status of the DIR field is a '0' or '1' (train direction), but the status of both the TPD and ICO fields are not '1', then an alarm should be reported.
16. Event records indicate lock out protection is being provided on a particular track approach. If it is indicated that lock out protection is being provided in message 9.4.45, than an alarm should be reported.
17. Event records indicate a loss of primary power, a switch to battery power, or changes in voltages. This should be determined by monitoring the Power (On/Off) field of message 9.4.45. If the status of the Power (On/Off) field changes, then an alarm should be reported.
18. Event records indicate that either the highway traffic signal controller cabinet or railroad grade crossing equipment bungalow door has been opened, allowing access to the equipment and settings. This should be determined by monitoring the Main Cabinet Door (Open/Closed) field of message 9.4.46 or the Entrance Alarm (Open/Closed) field of message 9.4.45. If the status of either fields change, then an alarm should be reported.

3.1.2 Hybrid Systems

"Hybrid" systems are existing systems having some level of event recording and/or processing capabilities. This includes a wide variety of existing system configurations of varying age and technology capabilities of technology in both the highway and railroad systems.

Highway agencies and railroads should jointly determine if they will upgrade their respective systems to support the IEEE Standard 1570 serial communication interface. The upgrade would require updating various existing equipment executive software and programs to generate and process the defined ATC and wayside messages. In some instances, upgrades may require completely new installations. In either case, the requirements of 49 CFR 236 Subpart H will need to be met.

Existing event recording devices may also require updates to their executive software or programs to support IEEE Standard 1570. The event recording devices should be able to monitor the status of message fields being sent across the serial communication interface between the highway and railroad gateway devices. This allows events to be recorded and alarms to be reported. If necessary, the communications capabilities of the event recording devices may need upgrading to support the transfer of events associated with alarms to a central office database.

If highway agencies and railroads do not jointly upgrade their respective equipment to support IEEE Standard 1570, then their systems should support a minimum level of monitoring, event recording, and alarm reporting required of legacy systems (see "Legacy Systems"). Highway agencies and railroads may consider future upgrades to support communication capabilities using IEEE Standard 1570.

Figure 6 shows a functional block diagram of a typical hybrid system configuration.

Figure 6: Hybrid System Configuration Functional Block Diagram

3.1.3 Legacy Systems

"Legacy" systems are existing systems having no event recording and/or processing capabilities. These systems will need to be modified to include new event recording equipment capable of future communication via IEEE Standard 1570.

Figure 7 shows a functional block diagram of a typical legacy system configuration.

Figure 7: Legacy System Configuration Functional Block Diagram

Event Recording

Legacy system configurations should be equipped with an event recording device to monitor the highway and railroad systems. The recording device(s) should be capable of supporting IEEE Standard 1570 serial communication should the location receive future upgrades utilizing this interface. The recording device(s) should support the number of digital and analog inputs required to monitor the highway and railroad. Event recorders should be able to process the various digital and analog inputs to monitor the status of the highway traffic signal and railroad grade crossing equipment and record the required events as necessary. The minimum events to record, along with explanations, is provided below. These events/circuits are intended for those existing systems that are currently incapable of and/or not utilizing the IEEE Standard 1570 communication protocol.

Highway Events

1. Preempt Active/Inactive
   This should record the change in state of preemption controller input based on the MUTCD standard hierarchy (drawbridge, railroad, emergency, transit). Specific to rail operation, there should be one input for each rail preemption circuit entering the highway traffic signal controller cabinet.
   
   Field Termination should record the first electrical termination in the highway traffic signal controller cabinet from the rail control circuit. A change in status at the first electrical termination in the highway traffic signal controller cabinet should be recorded as an event. This will identify if an active preemption call was received by the highway traffic signal controller cabinet assembly from the railroad control system.
   
   Traffic Controller Input should record the electrical termination in the highway traffic signal controller cabinet as it provides the preemption input to the highway traffic signal controller. A change in status of the preemption input into the highway traffic signal controller should be recorded as an event. This will identify if an active preemption call was properly routed through interface circuitry to initiate a valid preemption sequence.

2. Vehicle/Pedestrian Signal
   This should record phases, overlaps, and displays for vehicle and pedestrian signals. Circuit status should be provided at the termination point used for connecting the highway traffic signal control system with vehicle and pedestrian signal displays ("green", "walk", etc.). This information should be logged for a time period of at least 60 seconds, but not less than the highway traffic signal cycle length, prior to a rail preemption call and for an equal time period after the call for rail preemption is terminated.

3. Right-of-Way Transfer Time
   This should record the status of the right-of-way transfer time in the highway traffic signal preemption sequence (when it commences and terminates). The right-of-way transfer time is the amount of time needed for the highway traffic signal equipment to react to a preemption call plus any green, yellow, red, pedestrian walk, or pedestrian clearance time prior to the track clearance green interval.

4. Track Clearance Green Interval
   This should record the status of the track clearance green interval in the highway traffic signal preemption sequence (when it commences and terminates). The track clearance green interval is the portion of the traffic signal sequence after completion of the right-of-way transfer time when the green signal indications are displayed to roadway users in order to vacate the highway-rail grade crossing based on the minimum track clearance distance.

5. Flash Operation
   This should distinguish between conditions upon which an intersection operates in flash mode: conflict monitor trigger, manual switch trigger, or time of day programming trigger. In conflict monitor or manual switch mode, the highway traffic signal controller cannot initiate the preemption sequence. In time of day mode, the highway traffic signal controller can initiate the preemption sequence. The input provided from the highway traffic signal controller cabinet electrical bus connected to flash transfer relays should be monitored and a change in status should be recorded as an event.

6. Cabinet Electrical Service
   This requires monitoring for deviations in electrical service voltages that would trigger the conflict monitor/malfunction management unit. Any deviation in the electrical service triggering the conflict monitor/malfunction management unit, as defined by the highway agency, should be recorded as an event. This serves to identify the stability of electrical service.

7. Main Cabinet Door (Open/Closed)
   This requires monitoring of highway traffic signal controller cabinet access, prompting further examination of the various devices and data programming to determine if changes have been made. This is particularly beneficial if the highway traffic signal controller cabinet has been accessed in between inspections. The input should be provided through an appropriate electrical switch connected to the main highway traffic signal controller cabinet door that detects change in status between when the door is opened or closed. A change in status between "Open" and "Closed" should create an event and an alarm reported.

Railroad Events

1. Railroad Preemption Request
   This requires the railroad preemption relay (PER) to be monitored for a change in status (when the relay drops or picks up) and record it as an event. This recorded event serves to identify when an active railroad preemption call was placed.
   
   Some highway-rail grade crossings may have a second preemption relay installed in order to send an additional preemption request to the highway traffic signal controller. For example, a second preemption request may be sent when the gates reach horizontal, indicating that traffic is no longer permitted to enter the crossing and the highway traffic signal controller can terminate the track clearance green interval and hold the traffic signal green in the parallel direction. The status of any additional preemption relays should be monitored and a change should also be recorded as an event.
2. Supervisory Circuit
   This requires the supervisory circuit on the railroad interconnection preemption circuit to be monitored. A change in status of the supervisory relay (when it picks up or drops) should be recorded as an event.
3. Approach Circuits
   This requires the approach circuit for each track in each direction to be monitored for train presence detection. A change in status of the approach circuit relay (when it drops or picks up) should be recorded as an event. This recorded event serves to identify when a train is detected entering or exiting an approach.
4. Railroad Crossing Relay
   This requires the status of the railroad crossing relay (XR) to be monitored and for a change in status (when the relay drops or picks up) to be recorded as an event. In some newer systems, there may no longer be a physical XR relay to monitor. At these locations, the internal logic in the processors of the railroad grade crossing controller or predictor carries out the function of the grade crossing relay by assigning variables in a logical expression to set the status of the grade crossing warning system. The status of these variables should be monitored and a change should be recorded as an event. This recorded event serves to identify when the railroad grade crossing warning system is activated.
5. Entrance Gate Status
   Entrance gates at the highway-rail grade crossing should be monitored for a change in status. This requires the equipment and ability to monitor gate up and gate down contacts in either the interconnection circuits or the gate circuits. A change in status of the gate contacts between "Entrance Gate(s) Up" and "Entrance Gate(s) Not Up" or "Entrance Gate(s) Down" and "Entrance Gate(s) Not Down" should be recorded as an event.
6. Exit Gate Status (If present)
   If exit gates are present at the highway-rail grade crossing, they should be monitored for a change in status. This requires the equipment and ability to monitor gate up and gate down contacts in either the interconnection circuits or the gate circuits. Any change in status of the gate contacts between "Exit Gate(s) Up" and "Exit Gate(s) Not Up" or "Exit Gate(s) Down" and "Exit Gate(s) Not Down" should be recorded as an event.
7. Island Circuit Occupancy
   This requires the island circuits for each track to be monitored for train presence detection. A change in status of an island circuit relay (when the relay drops or picks up) should be recorded as an event.
8. Train Direction
   The direction of a train movement is determined by the status of the directional stick relays on each track. In some newer systems, there may not be physical directional stick relays to indicate train direction. At these locations, the internal logic in the processors of the railroad grade crossing controller or predictor carries out the function of the directional stick relays by assigning them as variables in a logical expression relating train presence detection on the approach and island circuits to the train's direction. Once a train has been detected on an approach circuit and an island circuit consecutively, the train's direction is determined and the appropriate directional stick relay picks up or directional stick variable is set to indicate the direction of the train's movement. The status of the directional stick relays or directional stick variables should be monitored and a change in status should be recorded as an event.
9. Lock Out Protection
   If provided, lock out protection should be monitored for each train movement through a highway-rail grade crossing. After a train movement has completed, if the trailing circuit does not clear after a preset time interval, an event record should be created and an alarm reported.
10. Power (On/Off)
    This requires the electrical power source for the railroad grade crossing equipment bungalow to be monitored for any loss of power and switch to battery power. The power off relay (POR) switches the power source that feeds the bungalow. When there is a loss of power, the POR drops to switch the bungalow to the battery power supply. A change in status of the power off relay (when it drops or picks up) should be recorded as an event and an alarm reported. Additionally, any changes in voltages that would result in an alarm being reported, as determined by the operating railroad, should create an event record.
11. Entrance Alarm (Open/Closed)
    This requires the bungalow door switch to be monitored for a change in status between "Open" and "Closed". A change in status should create an event and an alarm reported. This may require the installation of an electrical switch in existing railroad grade crossing equipment bungalows that changes state when the door is opened and closed. This event record would allow the railroad to determine when someone has had access to the bungalow and the equipment and therefore, when further examination of various devices and programming may be necessary.

Alarm Reporting

In addition to monitoring the status of various highway and railroad equipment and recording the required events, the device should be able to process this information in order to flag recorded events and/or report alarms. Event recorders should use user-specific logical expressions to relate the status of equipment to determine that the highway and railroad systems are working as designed. As defined by the highway agency and/or railroad, any recorded event or logical combination of events should be flagged as an alarm. A list of situations that should result in the reporting of an alarm along with explanations of how they can be determined is provided below. At a minimum, flagging event records will allow highway and railroad maintenance personnel to determine if a problem exists at a highway-rail grade crossing during regular maintenance or inspections. The following is a list of proposed situations for which an alarm should be reported. These alarms should be determined by monitoring the circuits and recorded events previously described. Event recorders should be capable of processing and relating the recorded events described in order to trigger the alarm(s).

1. Event records indicate that the preemption circuit does not drop or a railroad preemption request was not sent prior to the design preemption warning time. This should be determined by comparing the time stamps of the events recorded when the preemption relay (PER) drops and when an island circuit relay drops, indicating train presence is detected on an island circuit. If the preemption warning time is less than the preemption design time, then an alarm should be reported.
2. Event records indicate that a train is present on an approach circuit and the associated island circuit; however, there is no recorded event for a railroad preemption request. This should be determined by comparing the time stamps of events recorded when a track's approach circuit relay and island circuit relay drops, indicating train presence is detected on an approach and island circuit and when the PER drops. If a track's approach circuit relay and island circuit relay drops and the PER has not dropped, then an alarm should be reported.
3. Event records indicate that the supervisory relay does not pick up after a preemption request, signifying that the traffic controller did not confirm receipt of the preempt message; or the supervisory relay picks up when there is no preemption request, signifying a possible electrical problem in the interconnection. This should be determined by comparing the status of the PER and supervisory relays. If the PER has dropped and there is no event indicating that the supervisory relay has dropped, or if the supervisory relay drops and there is no event indicating that the PER dropped, then an alarm should be reported.
4. Event records indicate that the XR, which activates the grade crossing warning system, does not drop or activate the warning system before the specified warning time. This should be determined by comparing the time stamps of the events recorded when the XR drops and when an island circuit relay drops, indicating a train is detected on an island circuit. If the warning time is less than the design warning time, then an alarm should be reported.
   
   Alternatively, some newer systems may not have a physical XR to activate the warning system. At these locations, the internal logic in the processors of the railroad grade crossing controller or predictor carries out the function of the grade crossing relay by assigning variables in a logical expression to set the status of the grade crossing warning system. If recorded events indicate that the warning system is activated before the specified warning time, then an alarm should be reported.
   
   49 CFR 234.225 requires the activation of the grade crossing warning system at least 20 seconds prior to the train occupying the crossing. Train occupancy of the crossing is determined by the train presence detection on the appropriate island circuit.
5. Event records indicate that the entrance gate(s) begins to descend prior to the 49 CFR 234.223 required minimum of three seconds after the grade crossing warning system is activated and the flashing lights begin to operate. This should be determined by comparing the time stamps of the recorded events when the XR drops, indicating activation of the grade crossing warning system, and when the entrance gate(s) begins to descend. If the entrance gate(s) begin to descend less than three seconds after the XR drops, then an alarm should be reported.
6. Event records indicate that the entrance gate(s) reach horizontal position after the required minimum of five seconds prior to a train arriving at the highway-rail grade crossing, or when a train is detected on the island circuit. This should be determined by comparing the time stamps of the recorded events when the gate(s) reach horizontal position and when an island circuit relay drops, indicating a train is detected on an island circuit. If the island relay drops less than five seconds after the gate(s) reach horizontal position, then an alarm should be reported.
7. Event records indicate that the exit gate(s) begins to descend prior to the completion of the track clearance green interval, potentially trapping vehicles in the highway-rail grade crossing. This should be determined by comparing the time stamps of recorded events for when the exit gate(s) leaves the vertical position and when the track clearance green interval has terminated. If the exit gate(s) leave the vertical position before an indication that the track clearance green interval has terminated, then an alarm should be reported.
8. Event records indicate that an entrance or exit gates(s) has left the vertical position, but there is no recorded event indicating the gate(s) has reached the horizontal position within a preset time interval. This should be determined by comparing the time stamps of events recorded when the status of entrance or exit gate(s) change. If the entrance or exit gate(s) have left the vertical position, and there is no recorded event showing the entrance or exit gate(s) has reached the horizontal position before a present time interval, then an alarm should be reported.
   
   Alternately, event records indicate an entrance or exit gate(s) has left the horizontal position, but there is no recorded event indicating the gate(s) has reached the vertical position within a preset time interval. If the entrance or exit gate(s) have left the horizontal position and there is no recorded event showing the entrance or exit gate(s) have reached the vertical position, then an alarm should be reported. Part 3.3.30 of the AREMA C&S Manual states that gate arms should fully raise in no more than 12 seconds, or as instructed.
   
   Finally, event records indicate that an entrance or exit gate(s) is in both the vertical and horizontal position. If the status of the entrance or exit gate(s) indicates they are in the vertical position and also that they are in the horizontal position, then an error has occurred and an alarm should be reported.
9. Event records indicate that the right-of-way transfer time is longer than the design right-of-way transfer time. This should be determined by comparing the time stamps of the events recorded when the status of the right-of-way transfer time indicates it commences and terminates. If the right-of-way transfer time is longer than the design maximum right-of-way transfer time, then an error has occurred and alarm should be reported.
10. Event records indicate that the track clearance green interval is less than the design track clearance green interval. This should be determined by comparing the time stamps of the events recorded when the status of the track clearance green interval indicates it commences and terminates. If the track clearance green interval is less than the design track clearance green interval, then an error has occurred and an alarm should be reported.
11. Event records indicate that the amount of time from the start of the track clearance green interval to train presence detection on an island circuit is less than the design track clearance green interval. This should be determined by comparing the time stamps of the events recorded, when the status of the track clearance green interval indicates it commences and when an island circuit drops to indicate an island circuit is occupied. If the time between the start of track clearance green and island circuit occupancy is less than the design track clearance green interval, then an error has occurred and an alarm should be reported.
12. Event records indicate train presence detection on an island circuit, but there is no event record indicating the termination of the track clearance green interval. This should be determined by comparing the status of the island circuit relays and the status of the track clearance green interval. If the status of an island circuit relay drops, indicating island circuit occupancy, before indication that the track clearance green interval has terminated, then an error has occurred and an alarm should be reported.
13. Event records indicate train presence detection on an approach and island circuit, but the appropriate directional stick relay did not pick up, or a directional stick relay picks up when no train was detected. This indicates there may be an electrical problem with the circuits or relays.
    
    Alternatively, some newer systems may not have physical directional stick relays to indicate train direction. At these locations, the internal logic in the processors of the railroad grade crossing controller or predictor carries out the function of the directional stick relays by assigning them as variables in a logical expression relating train presence detection on approach and island circuits to the train's direction. Once a train has been detected on an approach circuit and an island circuit consecutively, the train's direction is determined and the appropriate directional stick variable is set to indicate the direction of the train's movement. If recorded events indicate train presence detection on a crossing track's approach and island circuits, but there is no recorded event indicating train direction, or if a recorded event indicates train direction when no train has been detected, then an alarm should be reported.
14. Event records indicate that lock out protection is being provided on a particular track approach. If it is indicated that lock out protection is being provided, than an alarm should be reported.
15. Event records indicate a loss of primary power, a switch to battery power, or significant changes in voltages. If an event record indicates a change in status of the power supply, then an alarm should be reported.
16. Event records indicate that either the highway traffic signal controller cabinet or railroad grade crossing equipment bungalow door has been opened, allowing access to the equipment and settings. If an event record indicates the status of either door changes, then an alarm should be reported.

3.1.4 General Event Recording Device Functional Requirements

This section describes the general functional requirements for event recording devices to be installed at highway-rail grade crossing locations with highway traffic signal preemption. These requirements are for event recording devices in any of the three system configurations (new, hybrid, and legacy).

The event recorder can be installed in the highway traffic signal controller cabinet, railroad grade crossing equipment bungalow, or in both. Highway agencies and railroads should jointly determine the location of the event recording device(s). The recording device should support time and date stamping of events and have sufficient capacity to record the required events from the highway and railroad for a period of one month prior to overwriting itself. The event recorder should have an internal battery backup to store data in the event of a power loss. For the required highway traffic signal events, the event recorder should dynamically record all required events for a time period of at least 60 seconds, but not less than highway the traffic signal cycle length, prior to a rail preemption call and for an equal time period after the call for rail preemption is terminated.

The event recording device should support two types of user interfaces. A visual display interface should dynamically indicate the status of each input, providing a valuable troubleshooting maintenance tool as well as supporting scheduled maintenance and inspection tasks. This requirement can be satisfied by a series of LED front panel indicators or an LCD alpha-numeric screen. A laptop computer or other portable device interface should provide for initial unit programming at the specific installation location as well as the ability to retrieve and display recorded event logs. If integrated as part of the highway traffic signal controller and/or railroad grade crossing controller, the controller should also support the computer/portable device requirement.

It is recommended that the event recording device support communications with an internet database or back office location to report alarms to the maintaining authorities as they occur. If an event recorder determines that alarm conditions have been met and flags an event record or several event records used to determine such conditions, it should report the alarm and send the associated event records to an internet database or back office system. This allows the highway agency and railroad to act as quickly as possible to investigate the problem. To support these features, the event recording devices should support an Ethernet-based connection to the back office system. This can be achieved by connecting through a high-speed communications link supplied to the equipment cabinet, or through wireless methods such as a cell modem connected to the event recorder. At remote locations, this communications link may not be achievable. The Ethernet connection should be shared by the maintaining agencies through a closed communications network. For new systems using IEEE Standard 1570 communication, the internet database or back office system receiving the reported alarms should support IEEE Standard 1570 so that it can process the alarms and recorded event messages sent to the database. This helps to initiate the required action from the highway agency and/or railroad maintenance personnel, if necessary.

Time Reference Requirements

The event recording device should maintain an accurate time reference. Traditionally, time referencing for highway traffic signal control devices had been based on the 60 Hz AC frequency of the utility generated service. However, it should be noted that on June 14, 2011, the Federal Energy Regulatory Commission stated that it is proposing an experiment that would allow more frequency variation in the nation's power grid. This may adversely impact time referencing systems that rely on electrical frequency for accuracy. Highway traffic signal controllers connected as part of a larger control system architecture may rely on a central device (system field master or remote computer station) to receive a time reference. In the event of power failure to the highway traffic signal controller, an internal crystal-based oscillator backed up by an internal battery should serve to keep time. The accuracy of this backup system would vary based on controller type and manufacturer.

In recent years, a GPS-based time reference system has begun to be used to maintain accurate time in a highway traffic signal controller. Typical installations consist of a small, round antenna installed on top of the highway traffic signal controller cabinet. There are two methods of transmitting the GPS information into the controller. The first method uses a contact closure as a single function input into the controller. (For example, this is typically a manufacturer-defined pin on the "D" connector for a NEMA TS-1 cabinet assembly.) The second method is for a serial connection into an unused communication port (RS232) on the controller.

For the event recorder, a GPS-based time reference should be used to maintain accurate time for both the highway traffic signal and railroad grade crossing recording systems. This should include the existing highway traffic signal controller and conflict monitor/malfunction management unit installed in the cabinet. All devices installed in the highway traffic signal controller cabinet and railroad grade crossing equipment bungalow should have the same time reference for event logging.

Electrical Requirements

The event recording device should be adaptable to accommodate variations in electrical data transmission based on signal cabinet/bungalow architecture. Each highway traffic signal controller and railroad grade crossing architecture utilizes different electrical levels and protocols for in-cabinet communications. NEMA TS-1, for example, employs a single function to single conductor architecture for device-to-device data transmission. A full eight-phase NEMA TS-1 traffic controller has 171 wires connected to it, allowing for +24 VDC (ground true) input/output to the unit. Type 170 and Type 179 use a similar configuration with a 102 conductor interconnection to the controller. NEMA TS2, type 1 uses serial data transmission (SDLC) to interface with other cabinet devices and terminals. The 2070 and other types of device cabinets have the user option to specify a variety of cabinet interface configurations including single function/single conductor or serial interface. For the event inputs identified, the input electrical levels will vary on cabinet type.

Electrical interfacing should conform to NEMA TS-2 "Traffic Controller Assemblies with NTCIP Requirements - Version 02.06" for NEMA-based cabinet assemblies; Caltrans "Transportation Electrical Equipment Specification" for 170-, 179-, and 2070-based cabinet assemblies; and "Advanced Transportation Controller (ATC) Standard" (latest approved version) for ATC-based cabinet assemblies. It should be noted that ATC Version 06.05 was the latest proposed at the time of this writing.

Environmental Requirements

The event recorder should be manufactured such that it meets the minimum environmental and test requirements as defined in NEMA TS-2 "Traffic Controller Assemblies with NTCIP Requirements - Version 02.06" for NEMA-based cabinet assemblies; Caltrans "Transportation Electrical Equipment Specification" for 170-, 179-, and 2070-based cabinet assemblies; and "Advanced Transportation Controller (ATC) Standard" (latest approved version) for ATC-based cabinet assemblies. The recording device should also meet the environmental requirements recommended in AREMA C&S Manual Part 11.5.1 "Recommended Environmental Requirements for Electrical and Electronic Railroad Signal System Equipment."

Inspection & Testing

Event recording devices should conduct self-diagnostics and testing as recommended in AREMA C&S Manual Part 3.1.29. Upon start-up and after reset, the recorders should perform self-diagnostics and the results of self-diagnostic tests should be recorded with a date and time stamp. The recorders should also verify proper operation and perform self-diagnostics periodically, while continuing to monitor and respond to status changes. If the tests are successful, the recorder should locally indicate being operational and, if possible, report being online and operational. If the tests are not successful, the recorder should create an event record and report an alarm. The recording devices should also verify input states by providing multiple sampling or time integration when evaluating the status of each input. Finally, the recorders should include a timer that requires the continuous servicing by the self-diagnostics in order to keep operating. If the timer expires, the recorder should reset itself and perform self-diagnostics upon resetting. This should also create an event record indicating the system was reset.

The event recording device should be tested to determine that it functions as intended when it is installed or modified and at least once a month, as required of grade crossing warning systems in 49 CFR 234. During regular joint inspections, highway agency and/or railroad inspecting personnel should download the recorded data from the event recording device to compare with known train events, if the data is not already regularly uploaded to and monitored from a back office database.

3.1.5 Event Recorder Costs

The cost of event recording devices varies based on the processing and reporting capabilities as well as storage capacity and recording needs of the highway-rail grade crossing. Larger highway-rail grade crossing locations or locations with more equipment that require additional monitoring and recording may require expanding the event recorder's inputs and outputs. Depending on the amount of information being recorded, event recorders may also need expanded memory so that they can store events for the required one month period prior to overwriting the memory. The geographic location of the highway-rail grade crossing and the available communication options will also impact the cost of event recording devices. For example, remote locations may require additional equipment for effective monitoring and alarm reporting.

Current pricing for basic event recording devices, without expanded inputs and outputs or memory, is between $1,500 and $2,500. Additional analog and digital I/O modules can cost from $500 to $2,000 depending on the size, type, and manufacturer. Memory expansion cards or modules can cost up to $1,000. Optional communication modules or cards typically cost up to $1,500. Given that the proposed event recorder will be required to contain more functionality than existing systems, event recording devices could cost up to $10,000 depending on the size of the location and necessary equipment. Back office systems needed for reporting alarms and remotely monitoring and testing highway-rail grade crossing equipment can cost from $10,000 to $150,000 based on the level of monitoring and automatic testing desired.

The prices for event recording devices capable of supporting IEEE Standard 1570 and monitoring the communication messages will most likely be greater than the costs provided here. These recording devices will need new executive software and the necessary communication options and equipment to support IEEE Standard 1570. Manufacturers will incur expenses for product development, which will in turn increase the costs of the new recording systems. Event recorder manufacturers typically provide railroads with discounted prices for buying in bulk, which vary based on the price of the product and quantity purchased.

3.2 Policy Information

3.2.1 Scope

Railroad maintenance standards and requirements for testing and inspecting highway-rail grade crossing signal systems are mandated by the Code of Federal Regulations Title 49 Part 234 Subpart D and AREMA. However, there is no national traffic signal counterpart to these standards and requirements. Traffic signal system maintenance, testing, and inspection processes are typically developed by State and local highway agencies. The following presents information pertaining to minimum maintenance, testing, and inspection policies and practices to be followed by State and local highway agencies for highway-rail grade crossing locations.

Relevant 49 CFR 234 sections are also presented. The ultimate goal is to encourage a working relationship between highway agencies and railroads through a joint testing and inspection procedure to ensure that highway-rail grade crossing signal systems and interconnected highway traffic signal systems are communicating correctly and working properly. Achieving this goal will satisfy the four actions recommended in the Safety Advisory 2010-02 noted in Chapter 1.

3.2.2 Frequency of Inspection and Testing

Performing preventive inspections and maintenance activities at highway-rail grade crossing locations is considered proactive risk management by State and local highway agencies. The Traffic Signal Installation and Maintenance Manual (4) recommends that these preventive inspections and maintenance activities be conducted at a 6-month intervals.

Railroads should perform inspections, testing, and maintenance activities at highway-rail grade crossing locations as required by 49 CFR 234.

Safety Advisory 2010-02 set forth requirements for State and local highway agencies to perform joint inspections in coordination with railroads at highway-rail grade crossing locations. The joint inspections should be performed at a maximum interval of twelve months.

3.2.3 Scheduling

It would be desirable for the 6-month preventive inspections and maintenance activities to be scheduled and initiated by the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. Ensuring that each highway-rail grade crossing with a jurisdiction is inspected and maintained within the specified interval may be the responsibility of the State (district) or local traffic engineer.

The monthly and quarterly inspections, testing, and maintenance activities conducted by the railroad should be scheduled and initiated as currently done in accordance with 49 CFR 234.

It is encouraged that the annual detailed joint inspections be scheduled and initiated by the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. The State (district) or local traffic engineer would be responsible to coordinate scheduling with the appropriate railroad. The State (district) or local traffic engineer would also ensure that each highway-rail grade crossing location within his/her jurisdiction is jointly inspected within the specified interval.

3.2.4 Responsibilities of Personnel

At least one highway traffic signal technician may conduct each 6-month preventive inspection and maintenance activity, verifying the elements identified under "Procedures". However, if deemed necessary, a traffic engineer may also perform the 6-month preventive inspection and maintenance activity. When two traffic personnel are present, the highway traffic signal technician would be responsible for the functionality of the highway traffic signal system whereas the traffic engineer would be responsible for the signal operations, signs, pavement markings, and other safety concerns.

Each monthly and quarterly inspection, testing, and maintenance activity performed by the railroad should be conducted by at least one railroad inspection/testing personnel. The railroad inspection/testing personnel should be responsible for the functionality of the railroad grade crossing warning system. The railroad inspection/testing personnel should be familiar with the requirements of 49 CFR 234 to ensure that all aspects of the highway-rail grade crossing are reviewed as specified.

Each detailed annual joint inspection may be conducted by at least one highway traffic signal technician, one traffic engineer, and one inspection/testing personnel from the railroad. The highway traffic signal technician would be responsible for the functionality of the highway traffic signal system whereas the traffic engineer would be responsible for the signal operations, signs, pavement markings, and other safety concerns. The railroad inspection/testing personnel should be responsible for the functionality of the railroad grade crossing warning system. Coordination between the highway traffic signal technician, the traffic engineer, and the railroad inspector is important to ensure that all aspects of the interconnected highway-rail grade crossing signal system are properly working.

3.2.5 Procedures

Identification

Highway-rail grade crossings that have interconnection between the highway traffic signal system and the railroad grade crossing warning system should be identified as such. The warning labels shown in Figure 8 may be affixed inside the main door of the highway traffic signal controller cabinet and the railroad grade crossing equipment bungalow, respectively.

Figure 8: Example Warning Labels

A field example of a warning label is shown in Figure 9. In addition to the warning, the label also includes contact information for the responsible highway agency and railroad.

Figure 9: Field Example of Warning Label

Plans

Signed and sealed plans required for proper testing and maintenance of the highway traffic signal system may be kept at each highway-rail grade crossing location within the highway traffic signal controller cabinet. This may also include signed and sealed plans for signing and pavement markings installed in advance of the highway-rail grade crossing on all roadway approaches. It is an effective practice to maintain legible and current plans that contain an accurate database of all programming resident in each of the various control devices. If modifications are made to the highway traffic signal system or to signing and pavement markings, modifying or replacing the plans within the highway traffic signal controller cabinet would be the duty of the highway agencies.

As required by 49 CFR 234.201, plans required for proper testing and maintenance of the railroad grade crossing warning system should be kept at each highway-rail grade crossing location in the railroad grade crossing equipment bungalow. It is the responsibility of the railroad to keep these plans legible and correct. If any modifications are made to the railroad grade crossing warning system, it is the responsibility of the railroad to modify or replace the plans contained in the railroad grade crossing equipment bungalow. Additionally, it should be the responsibility of the railroad to notify the appropriate highway agency of any changes made to the railroad grade crossing warning system that may have an impact on the operation of nearby highway traffic signal systems.

Six-month Highway Preventive Inspections and Maintenance Activities

The 6-month preventive inspections and maintenance activities are intended to verify that basic highway traffic signalization parameters are functioning properly, that appropriate signing and pavement markings are in place and in good condition, and that no other safety concerns are present. The items to be verified by a highway traffic signal technician (and traffic engineer, if present) may include the following:

• Signalization (vehicular and pedestrian, if present) to ensure that indications on all roadway approaches and at all pedestrian crossings are properly aligned and illuminated, when applicable.
• Signing to ensure that appropriate advance warning signs on all roadway approaches are present, visible, and in good condition.
• Pavement markings to ensure that appropriate pavement markings on all roadway approaches are present and in good condition.
• Visibility to ensure that sight triangles on all roadway approaches are clear of obstructions, particularly vegetation growth.
• Pavement condition to ensure that the surface on all roadway approaches is free of significant defects that would present a safety concern.
• Lighting to ensure that luminaires (if present) on all roadway approaches are functioning and providing sufficient illumination.
• Controller cabinet condition to ensure that the internal area is free of debris or animal infestations that may cause system malfunctions.

The issues identified through the 6-month preventive inspection process need to be brought to the attention of the appropriate responsible parties. Problems to be addressed immediately may include signalization, missing signing, and lighting outages. Additionally, seriously deteriorated pavement conditions should be given immediate attention while less significant deteriorations may be addressed in the short-term. Signing and pavement markings in poor condition may be updated at a regularly scheduled interval. It is important that controller cabinet debris or animal infestations be cleared at the time of the inspection.

Monthly and Quarterly Railroad Inspections and Maintenance Activities

The CFR regulations explain in detail the components of the railroad grade crossing warning system that should be inspected, tested, and maintained on a monthly and quarterly (3 month) basis. The purpose is to ensure that the warning system functions as designed, including being visible and audible to highway users approaching the crossing. At each of the specified intervals, railroad inspection/testing personnel should verify the following:

Monthly

• 49 CFR 234.257 - Warning System Operation:
  1. Each highway-rail crossing warning system shall be tested to determine that it functions as intended when it is placed in service. Thereafter, it shall be tested at least once each month and whenever modified or disarranged.
  2. Warning bells or other stationary audible warning devices shall be tested when installed to determine that they function as intended. Thereafter, they shall be tested at least once each month and whenever modified or disarranged.
• 49 CFR 234.261 - Highway Traffic Signal Preemption:
  Highway traffic signal preemption interconnections, for which a railroad has maintenance responsibility, shall be tested at least once each month.

The railroad having jurisdiction over the highway-rail grade crossing should be responsible for inspection, testing, and maintenance up to the point of interconnection with the highway traffic signal control system. The State or local highway agency should be responsible for inspecting, testing, and maintaining all remaining circuitry and highway traffic signal control devices. The test should ensure that an approaching train activates the railroad grade crossing warning system and initiates the highway traffic signal clearance sequence. The railroad should check contacts and devices interconnected with the highway traffic signals and advanced warning signs to ensure they perform as intended as defined in 49 CFR.

Inspection/testing personnel should also verify the proper operation of the interconnect circuit and observe that highway traffic signal preemption is operating as intended. Ideally, preemption should be verified with the actual passing of a train through the highway-rail grade crossing location; however, this is not always feasible. Under these circumstances, inspection/testing personnel may simulate a train movement by de-energizing the interconnection circuit, thereby activating the preemption sequence. If the crossing is equipped with advanced preemption, inspection/testing personnel should observe a train movement to verify proper operation. Inspection/testing personnel should note any repairs or adjustments made. If the interconnection circuit is discovered to be not operational and/or any inconsistency is discovered, inspection/testing personnel should notify the State or local highway agency having jurisdiction over the highway-rail grade crossing as well as report the findings to the appropriate railroad supervisor. If the railroad equipment is found to be operating properly and the highway traffic signal system does not respond, inspection/testing personnel should notify the State or local highway agency having jurisdiction over the highway-rail grade crossing of the problem. The railroad may request the presence of State or local highway agency personnel during the monthly preemption testing.

Quarterly

• 49 CFR 234.269 - Cut-out Circuits:
  Each cut-out circuit shall be tested at least once every three months to determine that the circuit functions as intended. For purposes of this section, a cut-out circuit is any circuit which overrides the operation of automatic warning systems. This includes both switch cut-out circuits and devices which enable personnel to manually override the operation of automatic warning systems.

• 49 CFR 234.271 - Insulated Rail Joints, Bond Wires, and Track Connections:
  Insulated rail joints, bond wires, and track connections shall be inspected at least once every three months.

These tests are used to assure that trains are being properly detected on each of the railroad approaches.

Detailed Annual Joint Inspections

The detailed annual joint inspections are intended to verify that all aspects of the interconnected highway-rail grade crossing signal system are properly working. It is desirable that the detailed annual joint inspections be conducted by highway agency and railroad personnel as described.

A highway traffic signal technician and traffic engineer may verify the following:

• Controller equipment to ensure that all installed units are in proper working order and that all connections are tight and secure. In particular, testing of the conflict monitor/malfunction management unit ensures that the interconnected highway-rail system reverts to safe mode in the event of failure. This would include both field testing and automated bench testing of the system.
• Vehicular and pedestrian timings to ensure that all traffic controller settings match the current master timing sheet.
• Preemption to ensure that, upon activation by an approaching train, the highway traffic signal system initiates and properly cycles the preemption sequence as specified on the plans and master timing sheet. This includes ensuring that the minimum activation warning time provided is sufficient to clear the highway-rail grade crossing of vehicular and pedestrian traffic prior to train arrival. Ideally, preemption would be verified with the actual passing of a train through the highway-rail grade crossing location; however, this is not always feasible. Under these circumstances, the railroad personnel may initiate the preemption sequence. Otherwise, the highway traffic signal technician may remove one of the connectors provided from the railroad to the highway traffic signal controller cabinet to activate preemption. This testing process needs to be conducted during coordinated operation, non-coordinated operation, and when other modes of signal operation are active, including emergency vehicle preemption and transit signal priority operation.
• Vehicle/pedestrian detection to ensure that detection systems installed on all approaches/crossings are in proper working order, that all connections within the controller are tight and secure, and that all inputs are being received and processed. Any existing/historical fault indicators need to be noted as problems to be rectified.

Railroad inspection/testing personnel should verify the following:

• 49 CFR 234.225 - Activation of Warning System:
  A highway-rail grade crossing warning system shall be maintained to activate in accordance with the design of the warning system, but in no event shall it provide less than 20 seconds warning time for the normal operation of through trains before the grade crossing is occupied by rail traffic.

• 49 CFR 234.259 - Warning Time:
  Each crossing warning system shall be tested for the prescribed warning time at least once every 12 months and when the warning system is modified because of a change in train speeds. Electronic devices that accurately determine actual warning time may be used in performing such tests.
  
  Railroads should ensure the grade crossing warning system activates as designed, and in no instance provides less than 20 seconds of warning time. Inspection/testing personnel should observe the crossing warning time and verify that it is in accordance with the designed warning system as shown on the circuit drawings. If an electronic device is installed at the highway-rail grade crossing location to accurately determine actual warning time, the warning time must be observed during a train movement or calculated by measuring the approach track circuits and using the highest timetable speed. If the warning time is found to be less than 20 seconds, inspection/testing personnel should immediately take corrective action and provide appropriate documentation.

• 49 CFR 234.263 - Relays:
  1. Except as stated in paragraph (b) of this section, each relay that affects the proper functioning of a crossing warning system shall be tested at least once every four years.
  2. (1) Alternating current vane type relays, direct current polar type relays, and relays with soft iron magnetic structure shall be tested at least once every two years. (2) Alternating current centrifugal type relays shall be tested at least once every 12 months.
  Railroad inspection/testing personnel should check relay operation for each track at the highway-rail grade crossing location and in each direction to ensure that the relays are de-energized after testing is complete. Railroads may provide specific instructions for inspection of each relay type and for testing with current and voltage.

• 49 CFR 234.265 - Timing Relays and Timing Devices:
  Each timing relay and timing device shall be tested at least once every twelve months. The timing shall be maintained at not less than 90 percent nor more than 110 percent of the 41 predetermined time interval. The predetermined time interval shall be shown on the plans or marked on the timing relay or timing device. Timing devices which perform internal functions associated with motion detectors, motion sensors, and grade crossing predictors are not subject to the requirements of this section.

During the detailed annual joint inspection process, it is desirable to maintain the normal operation of the highway-rail grade crossing. If normal operation is to be suspended, other provisions should be made prior to the inspection to ensure highway-rail grade crossing safety for all transportation modes at the location.

3.2.6 Documentation

For the 6-month preventive inspections and maintenance activities, a report completed by the highway traffic signal technician (and traffic engineer, if present) may include information such as the highway-rail grade crossing location, the technician's name (and traffic engineer, if present) and employee identification number, the date and time, the tasks performed, and the problems noted. A minimum of two copies of the 6-month report may be required, both signed by the highway traffic signal technician (and traffic engineer, if present). One report may be kept within the highway traffic signal controller cabinet and one may be filed at the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing. Upon the next inspection, the report within the highway traffic signal controller cabinet would be replaced. The report filed at the State (district) or local highway agency office may be discarded after a period of five years. If interim maintenance activities are required to the highway traffic signal system, it is important that signed documentation be attached to the most current report on file.

For the detailed annual joint inspections, a report should be completed by the highway traffic signal technician, traffic engineer, and railroad inspector. The report may include information such as the highway-rail grade crossing location, the participants' names and employee identification numbers, the date and time, the tasks performed, and the problems noted. A minimum of four copies of the joint inspection report may be required, signed by the highway traffic signal technician, traffic engineer, and railroad inspector. One report may be kept within the highway traffic signal controller cabinet, one may be filed at the State (district) or local highway agency office with jurisdiction over the highway-rail grade crossing, one should be kept within the railroad grade crossing equipment bungalow, and one should be filed in the office of a railroad supervisory official having jurisdiction, as required by 49 CFR 234.273. The reports within the highway traffic signal controller cabinet and the railroad grade crossing equipment bungalow would be replaced upon the next joint inspection. The report filed at the State (district) or local highway agency office may be discarded after a period of five years. The report filed with the railroad supervisory official should be kept until the next report for that test is filed and at least for one year, also as required by 49 CFR 234.273. If interim adjustments have been made to the highway traffic signal control system or railroad grade crossing warning system, it is important that signed documentation be attached to the most current report on file.

Several example inspection and diagnostic forms are attached in Appendix F. These forms can be modified by highway agencies and railroads for use during the 6-month preventive inspections and maintenance activities and the detailed annual joint inspection of highway-rail grade crossings.

3.2.7 Reference Documentation

The following reference documents may be consulted when performing inspections and maintenance activities:

• Manual on Uniform Traffic Control Devices (MUTCD) (7)
  • Part 8 - Traffic Control for Railroad and Light Rail Transit Grade Crossings
• Traffic Engineering Handbook (10)
• Traffic Control Devices Handbook (11)
• Code of Federal Regulations (6)
  • Title 49 - Transportation; Part 234 - Grade Crossing Signal System Safety and State Action Plans; Subpart D - Maintenance, Inspection, and Testing
• AREMA Communications and Signals Manual (9)
  • Section 3 - Highway-Rail Grade Crossing Warning Systems; Part 3.1.10 - Recommended Functional/Operating Guidelines for Interconnection Between Highway Traffic Signals and Highway-Rail Grade Crossing Warning Systems
  • Section 3 - Highway-Rail Grade Crossing Warning Systems; Part 3.3.1 - Recommended Instructions for the Maintenance and Test of Automatic Highway-Rail Grade Crossing Warning Systems
  • Section 3 - Highway-Rail Grade Crossing Warning Systems; Part 3.3.30 - Recommended Instructions for Inspection and Test of Highway-Rail Grade Crossing Warning System Installation Before Placing In Service
• Railroad-Highway Grade Crossing Handbook (12)