Note: This document summarizes current practices but does not set standards; practitioners are advised to check current local standards and requirements (refer to Disclaimer and Quality Assurance Statement). Users of the data provided within this document should anticipate possible variations from current information within the FRA databases, which are updated monthly.

This chapter discusses methods for selecting alternatives and provides information on MUTCD Interpretations, Experimentation, Changes, and Interim Approvals, which provide the best source of new guidance between updates to the MUTCD.

Methods to evaluate and select alternatives through engineering study and economic analysis techniques which are presented include the following:

• Updated "Technical Working Group" (TWG) Guidance
• Field Diagnostic Team Review Procedure
• Benefit-Cost Analysis
• Resource Allocation Procedure
• FRA GradeDec Software

Although procedures are provided for developing benefit-cost analyses of alternative treatments, more recent trends place emphasis on risk avoidance and best practices. As a result, benefit-cost studies may only be useful for evaluating alternatives that involve a major investment. In addition, the Rail-Highway Crossing Resource Allocation Procedure is presented and other low-cost solutions are discussed.

More involved economic analyses such as Benefit-Cost Analysis, Resource Allocation Procedures, and use of GradeDec may be more appropriate approaches to utilize when looking at multi-crossing scenarios, such as rail corridors or statewide efforts, or when considering tradeoffs between at-grade improvements vs. closures and grade separations.

The Technical Working Group TWG guidance, which relies upon readily available planning data, can provide a good initial approach.

Confirmation of treatments should include a field review using the Diagnostic Team Review procedure.

TECHNICAL WORKING GROUP GUIDANCE

Following the 1995 collision in Fox River Grove, IL, between a Metra commuter train and a school bus, which resulted in the deaths of seven students, the USDOT established a Technical Working Group (TWG) to develop "best practices" guidance on a selection of crossing treatments. The TWG included representatives from the FHWA, FRA, FTA, and NHTSA, along with traffic engineers and rail signaling engineers with a working knowledge of crossing treatments. The cooperation among the various representatives of the TWG represented a landmark interdisciplinary effort to enhance communication among railroad companies and governmental agencies involved in enhancing grade crossing safety.

The guidance developed by the TWG notes that a highway-rail crossing differs from a highway-highway intersection in that the train always has the ROW. From this perspective, the TWG highlights key considerations for deciding what type of highway traffic control device(s) are to be installed, if in fact a grade crossing should be allowed to remain. This, in turn, requires an assessment of what information the road user (specifically non‑motorized system users) needs to be able to cross safely and whether the resulting driver response to a traffic control device is "compatible" with the intended function of the highway and railroad facility. The TWG guidance outlines the role of stopping sight distance, approach (corner) sight distance, and clearing sight distance, and integrates this with highway system needs based upon the type and classification of the roadway as well as the allowable track speeds by class of track for the railway system.

The TWG guidance provided in this Handbook has been updated to reflect current practice. It is intended to assist engineers in the selection of traffic control devices or other measures at highway-rail crossings. It is not to be interpreted as policy or standards and is not mandatory. Any requirements that may be noted are taken from the MUTCD or other standards. A number of measures are included which may not have been supported by quantitative research but are being used by States and local agencies. This TWG guidance is for information purposes only.

Minimum Devices: All highway-rail crossings, including street-running railroads or transit systems on public streets or highways should be equipped with approved passive warning devices, as shown in MUTCD Part 8.

Minimum Widths: All highway-rail crossing surfaces should extend a minimum of 1 foot beyond the edge of the roadway shoulder, sidewalk, pathway or face of curb, as measured perpendicular to the roadway centerline.

Closure: Highway-rail crossings should be considered for closure and physically removed from the railroad right-of-way whenever one or more of the following apply:

• An engineering study determines a nearby crossing otherwise required to be improved or grade separated already provides acceptable alternate vehicular and pedestrian access
• If an engineering study determines any of the following apply:
  • Average Annual Daily Traffic (AADT) less than 1,000
  • Acceptable alternate access across the rail line exists within one (1) mile measured along the track
  • The median trip length normally made over the subject crossing would not increase by more than 2.5 miles
• If railroad operations will occupy or block the crossing for extended periods of time on a routine basis and it is determined that it is not physically or economically feasible to either construct a grade separation or shift the train operation to another location, and an engineering study determines that such a crossing should be closed to vehicular and pedestrian traffic. Such locations would typically include the following:
  • In or adjacent to rail yards and locations near industrial spur tracks where trains pick up or set out blocks of cars or switch local industries
  • Passing tracks primarily used for holding trains while waiting to meet or be passed by other trains
  • Locations where train crews are routinely required to stop for crew changes or for cross traffic on intersecting rail lines
  • In the proximity of stations where trains dwell for extended periods of time and block the crossing

It may be advisable to investigate whether to construct alternative roadway access in conjunction with closing the crossing when the subject crossing is currently the only access to a community.

Grade Separation: Grade separation should be provided at all limited access facilities and should be considered for whenever one or more of the following conditions exist:

• The posted highway speed equals or exceeds 55 mph
• AADT exceeds 30,000 in urban areas or 20,000 in rural areas
• Maximum authorized train speed exceeds 79 mph
• An average of 30 or more trains per day
• An average of 75 or more passenger trains per day in urban areas or 30 or more passenger trains per day in rural areas
• An average of 150 or more transit trains per day in urban areas or 60 or more passenger trains per day in rural areas
• Freight Train Crossing Exposure (the product of the number of trains per day and AADT) exceeds 900,000 in urban areas or 600,000 in rural areas
• Passenger Train Crossing Exposure (the product of the number of passenger trains per day and AADT) exceeds 2,250,000 in urban areas or 600,000 in rural areas
• Transit Train Crossing Exposure (the product of the number of transit trains per day and AADT) exceeds 4,500,000 in urban areas or 1,200,000 in rural areas
• The expected accident frequency for active devices with gates, as calculated by the USDOT Accident Prediction Formula including five-year accident history, exceeds 0.5 (per year). If the highway is a part of the designated National Highway System, the expected accident frequency for active devices with gates, as calculated by the USDOT Accident Prediction Formula including five-year accident history, exceeds 0.2 (per year)
• Vehicle delay exceeds 30 vehicle hours per day with consideration for cost effectiveness
• Whenever a new grade separation is constructed, whether or not it replaces an existing highway-rail crossing, consideration should be given to the possibility of closing one or more adjacent crossings. In addition, the railroad should be consulted prior to starting. design to determine the railroad's future clear span requirements for the tracks crossed
• Utilize Table 7 for LRT grade separations

Table 7. LRT Grade Separation

Trains Per Hour	Peak-Hour Volume (Vehicles Per Lane)
60	200
40	400
20	600

Source: Light Rail Transit Grade Separation Guidelines, An Informational Report. Washington, DC, ITE, Technical Committee 6A-42, March 1992.

PASSIVE WARNING DEVICES

• A circular railroad advance warning (W10-1) sign shall be used on each roadway in advance of every highway-rail crossing except as described in MUTCD Section 8B.06.
• If a Yield Ahead or Stop Ahead sign is to be installed on the approach to the crossing, the W10-1 sign should be installed upstream (further from the track) from the Yield Ahead or Stop Ahead sign.
• Except for crossings located within railroad yards or port and dock facilities, FRA regulations (49 CFR 234.311) require the installation of Emergency Notification System signs at highway-rail and pathway grade crossings, to provide information to road users so that they can notify the railroad company about unsafe conditions or malfunctioning active crossing warning devices.
• Where the roadway approaches to the crossing are paved, pavement markings are to be installed as described in MUTCD, subject to engineering evaluation.
• Where applicable, the "TRACKS OUT OF SERVICE" sign may be used to notify drivers that the tracks have been temporarily or permanently abandoned, but only until the tracks have been paved over or removed from the crossing.
• MUTCD Section 8B.04 discusses Crossbuck Assemblies, where one reflectorized Crossbuck sign and either a Yield sign or a Stop sign shall be used on each roadway approach to a highway-rail crossing.
  • If there are two or more tracks, the number of tracks should be indicated on a supplemental sign (R15-2) of inverted T shape mounted below the Crossbuck.
  • Strips of retroreflective white or red should be installed on the sign posts in accordance with MUTCD.

ACTIVE WARNING DEVICES

• If active devices are selected, railroad flashers with gates may be appropriate if the following conditions exist:
• Inadequate sight distance exists in one or more approach quadrants and it is not physically or economically feasible to correct the sight distance deficiency
• Regularly scheduled passenger trains operate near industrial facilities, such as stone quarries, log mills, cement plants, steel mills, oil refineries, chemical plants, and landfills
• Near schools, industrial plants, or commercial areas where there is substantially higher than normal usage by school buses, heavy trucks, or trucks carrying dangerous or hazardous materials
• Near a highway intersection or other highway-rail crossings and the traffic control devices at the nearby intersection cause traffic to queue on or across the tracks (in such instances, if a nearby intersection has traffic signal control, it should be interconnected to provide preempted operation, and traffic signal control should be considered if none)
• The crossing is in a rural area with tangent approaches that extend more than a mile and the speed limit equals or exceeds 55 mph
• Multiple tracks exist at or in the immediate crossing vicinity where the presence of a moving or standing train on one track effectively reduces the visibility of another train approaching the crossing on an adjacent track (absent some other acceptable means of warning drivers to be alert for the possibility of a second train)
• An average of 20 or more trains per day
• Posted highway speed equals or exceeds 40 mph in urban areas or equals or exceeds 55 mph in rural areas
• AADT exceeds 2,000 in urban areas or 500 in rural areas
• Multiple lanes of traffic in the same direction of travel (usually this will include cantilevered signals)
• The crossing exposure (the product of the number of trains per day and AADT) exceeds 5,000 in urban areas or 4,000 in rural areas
• As otherwise recommended by an engineering study or diagnostic team

If active devices are selected, a preempted traffic control signal without railroad warning devices may be appropriate if the following conditions exist:

• The crossing is located through the center of a roadway intersection. Typically, the traffic signals will be preempted and will hold in a dwell phase showing a red traffic control signal indication to all cross-track traffic. The traffic control signal should include battery backup power. Additional flashing-lights are not necessary if the traffic control signal will be controlling roadway traffic on and around the railroad track crossing.
• The crossing is located along the shoulder of the roadway that is parallel to the track and there is little to no storage for a design vehicle. Consideration should always be given to school bus use and truck traffic. If a traffic control signal is installed at the adjacent roadway intersection, the stop line should be placed on the opposite side of the track from the roadway intersection and the traffic control signal should be installed and operate in a manner that routinely stops vehicles before they enter the track area.

If active devices are selected, railroad flashers without gates may be appropriate if the following conditions exist:

• The crossing is located through the center of a roadway intersection. Typically, the traffic signals will need to be preempted and will hold in a dwell phase showing a red traffic control signal indication to cross-track traffic. The traffic control signal should have battery backup power.
• The crossing is located near a yard or multi-track location where frequent switching operations may occur within the approach circuit. Installation of gates may promote gate runner behavior if motorists frequently observe active devices operating with trains that do not cross the crossing. The use of flashing-lights alone requires the driver to stop and assess the situation before proceeding.
• The crossing is located on an industrial lead or spur track. Train operations through industrial areas where multiple turnouts leading to multiple dead-end tracks tend to be slow–near walking speed. As operations often necessitate stopping/switching in these areas, gate installation prevents motorists from stopping and proceeding during operations where the train will not cross into the roadway.
• The crossing is located next to an industry gate access. In these locations, train operations often require the train to pull near the gate slowly and stop so a train crew member can get off the train and unlock the gate before the train can proceed.

Roadway Realignment: In some circumstances, a crossing may have adverse geometric features which can be improved by realignment of the roadway. Examples include the following:

• Skew Angle Crossings
• Crossings with Adverse Profile due to roadway constraints
• Crossings on an approach to a multi-leg intersection
• Adjacent crossings which are on approaches to closely-spaced intersections
• Crossings with extremely poor corner sight distance
• Crossings at locations subject to recurrent queuing which cannot be cleared with typical treatments
• Crossings at locations near rail junctions subject to frequent blockage or switching activity

New Crossings: New highway-rail crossings should only be permitted when the following can be demonstrated:

• Where there is a clear and compelling public need (other than enhancing the value or development potential of the adjoining property for new highways or streets)
• Grade separation cannot be economically justified, i.e., benefit-to-cost ratio on a fully allocated cost basis is less than 1.0 (when the crossing exposure exceeds 50,000 in urban areas or exceeds 25,000 in rural areas)
• There are no other viable alternatives to provide access

If a crossing is permitted, the following conditions should apply:

• Whenever a new highway-rail crossing is constructed, consideration should be given to closing one or more adjacent crossings
• If it is a main track, the crossing should be equipped with active devices with gates
• The plans and specifications should be subject to the approval of the highway agency having jurisdiction over the roadway (if other than a State agency), the State department of transportation or other State agency vested with the authority to approve new crossings, and the operating railroad
• All costs associated with the construction of the new crossing should be borne by the party or parties requesting the new crossing, including providing financially for the ongoing maintenance of the crossing surface and traffic control devices where no crossing closures are included in the project
• Whenever new public highway-rail crossings are permitted, they should fully comply with all applicable provisions of this proposed recommended practice

Traffic Control Device Selection Procedure:

Step 1–Minimum highway-rail crossing criteria:

1. Gather preliminary crossing data:

Highway:

• Geometric configuration (number of approach lanes, alignment, median)
• AADT
• Speed (posted limit or operating)
• Functional classification
• Desired Level of Service (LOS)
• Proximity of other intersections (note active device interconnection)
• Availability and proximity of alternate routes and/or crossings
• Emergency response facilities
• Type of vehicle usage (trucks, buses, etc.)
• Stop line locations and storage distances

Railroad:

• Number of tracks (type: FRA classification, mainline, siding, spur)
• Number of trains (passenger, freight, other)
• Timetable track speed and operational characteristics
• Proximity of rail yards, stations, terminals, spurs, and railroad wayside equipment (defect detectors, train signals, etc.)
• Crossing signal control circuitry

Traffic Control Device:

• Passive or active
• Existence of traffic signal(s) and preemption
• Road approach traffic control signal timing (coordinated or uncoordinated)
• Supplemental devices (approach warning beacons, supplemental flashers, etc.)

Prior Collision History

2. Based on one or more of the above, determine whether any of the recommended thresholds for closure, installing passive or active devices, or grade separation have been met based on highway or rail system operational requirements

3. Consider crossing closure based on the criteria noted earlier in this section

Step 2–Evaluate highway traffic flow characteristics:

1. Consider the required motorist response to the existing (or proposed) type of traffic control device. At passive crossings, determine the degree to which traffic may need to slow or stop based on evaluation of available corner sight distances

2. Determine whether the existing (or proposed) type of traffic control device and railroad operations will allow highway traffic to perform at an acceptable LOS for the functional classification of the highway

Step 3–Possible revision to the highway-rail crossing:

1. If crossing closure or consolidation is being considered, determine the feasibility and cost of providing of an acceptable alternate route and compare this to the feasibility, benefits of safety modifications and cost of improving the existing crossing

2. If grade separation is being considered:

• Economic analysis should consider fully allocated life-cycle costs
• Consider highway classification and LOS
• Consider the possibility of closing one or more adjacent crossings
• Consider future traffic generation from population growth

3. If there is inadequate sight distance related to the type of control device for stopping, approach speed, or clearing, consider measures such as:

• Trying to correct the sight distance limitation
• Closing the crossing
• Grade separating the crossing
• Performing an engineering study to determine the need for a STOP sign in lieu of the required YIELD sign at the crossing
• Performing an engineering study to determine the safe approach speed and consider either posting an advisory speed plaque at the advance warning sign or reduce the regulatory speed limit on the approach
• Upgrading a passive or flashing-light-only traffic control device to active with gates

4. If active devices are being considered, the devices should be installed with consideration to what is discussed earlier in this section

PEDESTRIAN TREATMENTS

The following discussion draws upon the research found in the Engineering Design for Pedestrian Safety at Highway-Rail Grade Crossings. ⁽⁴²⁾ Pedestrian behavior at or adjacent to railroad tracks can be characterized as risky.

Six criteria regarding the pedestrian crossing environment and the desired devices and controls for it, were published by the Transit Cooperative Research Program in Report 69:⁽³¹⁾

• Pedestrian facilities and minimum pedestrian activity present or anticipated
• LRT speed exceeds 35 miles per hour
• Sight distance restricted on approach
• Crossing located in school zone
• High pedestrian activity levels occur
• Pedestrian surges or high pedestrian inattention

Whereas the above criteria were developed for LRT applications, these criteria may be used to evaluate the need for commonly-used pedestrian treatments.

Devices and treatments identified in the Engineering Design for Pedestrian Safety at Highway-Rail Grade Crossings include the following:

Passive devices for pedestrian crossings

• Pedestrian swing gates
• Directional surface
• Flange fillers and surfacing
• Dynamic envelope markings
• Z-crossings (zig-zag)
• Channelization
• Oversized ballast
• Bedstead barriers
• Fencing
• Anti-trespass panels

Active devices for pedestrian crossings

• Smart warning systems
• Detectable warning and tactile strips
• Pedestrian gates
• Gate skirts

Pedestrian behavior that violates traffic control at crossings can undermine the effectiveness of treatments at crossings. It has been noted that new treatments installed to mitigate some types of risky pedestrian behavior result in new forms of risky behavior; for example, pedestrians may pull open a swing gate intended for emergency egress and evade a lowered pedestrian gate.

Determining the most applicable type of treatment to use is a site-specific decision based on several criteria, site assessments, and other noteworthy practices.

DIAGNOSTIC STUDY METHOD

Current practice in crossing treatment selection utilizes the diagnostic study method. The approach centers on a field survey procedure using a "Diagnostic Team" composed of experienced individuals knowledgeable in key disciplines including crossing design, safety engineering, rail operations and signaling, and traffic engineering.

This approach is intended to ensure that site-specific features are considered in adapting guidance and standards for treatments to address the issues at a crossing. The diagnostic study method can also provide an interdisciplinary approach which reflects all the technical considerations in selection of a treatment alternative.

As such, the diagnostic study method, supported by additional engineering analyses conducted offsite, provides a structured approach which might satisfy the various requirements for "Engineering Study" as defined in the MUTCD (Part 1A.13). Refer to Appendix C of this Handbook for specific procedures.

ECONOMIC BENEFIT-COST ANALYSIS

An economic analysis may be performed to determine possible alternative improvements that could be made at a highway-rail crossing. The FHWA Highway Safety Benefit Cost Analysis Guide⁽⁴³⁾ and companion Highway Safety Benefit Cost Analysis Tool⁽⁴⁴⁾ and support materials available at the FHWA Highway Safety Improvement Program (HSIP) website can be used by practitioners to evaluate safety improvement alternatives. Practitioners need to assemble information on the following elements, using the following best available facts and estimates:

• Collision costs
• Service life
• Initial improvement costs
• Maintenance costs
• Salvage value
• Traffic growth rates

Other considerations include the effectiveness of the improvement in reducing collisions and the effects on travel, such as reducing delays.

The selection of collision cost values is of major importance in economic analyses. Considerable care should be used in establishing values for these costs. The following are the two most common sources of collision costs:

• National Safety Council (NSC)
• NHTSA

The NSC costs include wage losses, medical expenses, insurance administrative costs, and property damage. The NHTSA includes the calculable costs associated with each fatality and injury plus the cost to society, such as consumption losses of individuals and society at large caused by losses in production and the inability to produce. Many States have developed their own State-specific values. Whichever is selected, the values should be consistent with those used for other safety improvement programs. An appropriate method of discounting should be used to account for inflation and opportunity cost. The selected discount rate should be informed by current practices and should be documented as part of the analysis.

The service life of an improvement should be equal to the time that the improvement can affect collision rates. Both costs and benefits should be calculated for this time. Hence, the service life is not necessarily the physical life of the improvement. For highway-rail crossings, however, it is a reasonable assumption that the improvement would be equally effective over its entire physical life. Thus, selecting the service life equal to the physical life would be appropriate.

The selected service life can have a profound effect on the economic evaluation of improvement alternatives; therefore, it should be selected using the best available information.

Project costs should include initial capital costs and maintenance costs and should be considered life-cycle costs; in other words, all costs are distributed over the service life of the improvement. The installation cost elements include the following:

• Preliminary engineering
• Labor
• Material
• Lease or rental of equipment
• Miscellaneous costs

The maintenance costs are all costs associated with keeping the system and components in operating condition.

The salvage value may be an issue when a highway is upgraded or relocated, or a railroad line is abandoned. Salvage value is defined as the dollar value of a project at the end of its service life and, therefore, is dependent on the service life of the project. For crossing signal improvement projects, salvage values are generally very small. Due to the characteristics of crossing signals and control equipment as well as the liability concerns that arise from deploying signal equipment that has already been used, it is assumed that there is zero salvage value after 10 years.

RESOURCE ALLOCATION PROCEDURE

In lieu of the economic analysis procedures described above, USDOT has developed a resource allocation procedure for highway-rail crossing improvements. The FRA's User's Guide, Rail-Highway Crossing Resource Allocation Procedure, Third Edition (1987), can be accessed here: https://railroads.dot.gov/elibrary/rail-highway-crossing-resource-allocation-procedure-users-guide-third-edition. This procedure was developed to assist States and railroads in determining the effective allocation of federal funds for crossing traffic control improvements

The resource allocation model is designed to provide an initial list of crossing traffic control improvements that would result in the greatest collision reduction benefits based on cost-effectiveness considerations for a given budget. As designed, the results are checked by a diagnostic team in the field and revised as necessary. It should be noted that the procedure considers only traffic control improvement alternatives as described below:

• For passive crossings, single track, two upgrade options exist: flashing-lights or gates
• For passive, multiple-track crossings, the model allows only the gate option to be considered in accordance with the Federal-Aid Policy Guide
• For flashing-light crossings, the only improvement option is gates

Other improvement alternatives, such as removal of site obstructions, crossing surface improvements, illumination, and train detection circuitry improvements, are not considered in the resource allocation procedure.

The input data required for the procedure consists of the number of predicted collisions, the safety effectiveness of flashing-lights and automatic gates, improvement costs, and the amount of available funding.

The number of annual predicted collisions can be derived from the USDOT Accident Prediction Model or from any model that yields the number of annual collisions per crossing.

Safety effectiveness studies for the equipment used in the resource allocation procedure have been completed by USDOT, the California Public Utilities Commission, and William J. Hedley. Effectiveness factors are the percent reduction in collisions occurring after the implementation of the improvement.

The model requires data on the costs of the improvement alternatives. Life-cycle costs of the devices should be used, such as both installation and maintenance costs.

Costs used in the resource allocation procedure are usually developed for each of the following three alternatives, as applicable:

• Passive devices to flashing-lights¹
• Passive devices to automatic gates
• Flashing-lights to gates

¹ Practitioners are cautioned to determine whether use of flashing lights without gates is appropriate for such locations; refer to the Technical Working Group guidance in this section.

Caution should be exercised in developing specific costs for a few selected projects while assigning average costs to all other projects. If this is done, decisions regarding the adjusted crossings may be unreasonably biased by the algorithm.

The amount of funds available for implementing crossing signal projects is the fourth input for the resource allocation procedure are at multiple track crossings.

The discussion which follows assumes that a group of crossings, some of which are at single-track sections and others where there are two or more tracks are being evaluated and that some crossings are passive whereas others have flashing-lights but no gates. The goal of the analysis is to prioritize crossings for improvement based upon cost-effectiveness, as explained further below.

If, for example, a single-track passive crossing is considered, it could be upgraded with either flashing-lights, with an effectiveness of E₁, or gates, with an effectiveness of E₂. The number of predicted collisions at crossing "i" is A_i. Therefore, the reduced accidents per year is A_iE₁ for the flashing-light option and A_iE₂ for the gate option. The corresponding costs for these two improvements are C₁ and C₂. The accident reduction/cost ratios for these improvements are A_iE₁/C₁ for flashing-lights and A_iE₂/C₂ for gates. The rate of increase in accident reduction versus costs that results from changing an initial decision to install flashing-lights with a decision to install gates at the crossing is referred to as the incremental accident reduction/cost ratio and is equal to:

A_i(E₂-E₁)/(C₂-C₁)

If, on the other hand, the crossing was a passive crossing in multiple-track territory, then improvements to flashing-lights would not be an option. In this scenario, the upgrade from passive to gates would result in an effectiveness of E₂, a cost of C₂, and an accident reduction/ cost ratio of A_iE₂/C₂. If this multi-track crossing was originally a flashing-light crossing, the improvement from flashing-lights to gates would be characterized with an effectiveness of E₃, a cost of C₃, and an accident reduction/cost ratio of A_iE₃/C₃.

The individual accident reduction/cost ratios associated with these improvements are selected by the algorithm in an efficient manner to produce the maximum accident reduction that can be obtained for a predetermined total cost. This total cost is the sum of an integral number of equipment costs (C₁, C₂, and C). The total maximum accident reduction is the sum of the individual accident reductions of the form AxE.

The USDOT Rail-Highway Crossing Resource Allocation Procedure, as described in the Rail-Highway Crossing Resource Allocation Procedure's Guide, Third Edition, August 1987, DOT/ FRA/OS-87/10, uses three "normalizing constants" in the accident prediction formula.⁽⁴⁵⁾ These constants need to be adjusted periodically to keep the procedure matched with the current accident trends, the current number of open public at-grade crossings, and the changes in the warning devices.

For the most recently calculated 2013 normalizing constants, the collision data that was used was for calendar years 2007-2011 (to predict 2012 accidents/incidents). The process of determining the three new normalizing constants for 2013 was performed such that the sum of the 2012 accident prediction values of all open public at-grade crossings in the National Highway Rail Crossing Inventory data that was used was made to equal the sum of the observed number of collisions. Note that while mismatched data records between accident/inventory reporting are included, those accidents which occurred prior to the date of a warning device change are excluded, and also excluded are accidents which occurred at closed crossings and nonpublic at-grade crossings as included in the Inventory data used. This process was performed for each of the respective formulae for the three types of warning device categories: passive, flashing-lights, and gates. This process normalizes the calculated predictions for the current trend in collision data for each category and relative to each of the three types of warning device categories (see Table 8).

Table 8. Collision Prediction and Resource Allocation Procedure Normalizing Constants

Warning Device Groups	New*	Prior years
	2013	2010	2007	2005	2003	1998	1992	1990	1988	1986
Passive	0.5086	0.4613	0.6768	0.6407	0.6500	0.7159	0.8239	0.9417	0.8778	0.8644
Flashing-lights	0.3106	0.2918	0.4605	0.5233	0.5001	0.5292	0.6935	0.8345	0.8013	0.8887
Gates	0.4846	0.4614	0.6039	0.6513	0.5725	0.4921	0.6714	0.8901	0.8911	0.8131

Source: Federal Railroad Administration websit (http://safetydata.fra.dot.gov/officeofsafety/default.aspx).

The most current Normalizing Constants are used in FRA's Web Accident Prediction System (WBAPS), on the FRA Safety Data website. Practitioners are encouraged to access this system which can provide the risk reduction factors based upon data in the USDOT grade crossing database.⁽⁴⁶⁾ If the resource allocation procedure is used to identify high-hazard crossings, a field diagnostic team should investigate each selected crossing for accuracy of the input data and reasonableness of the recommended solution. A worksheet for performing this analysis is included in Figure 61 (or download from this link https://www.fhwa.dot.gov/safety/legislative-safety-programs/xings/highway-rail-crossing-handbook-third-edition-0).

This worksheet also includes a method for manually evaluating or revising the results of the computer model.

Figure 61. Resource Allocation Procedure Field Verification Worksheet

Source: FRA webste.

FRA GRADEDEC SOFTWARE

The FRA developed the GradeDec.NET (GradeDec) highway-rail grade crossing investment analysis tool to provide grade crossing investment decision support. The GradeDec provides a full set of standard benefit-cost metrics for a rail corridor, a region, or an individual grade crossing. Model output allows a comparative analysis of grade crossing alternatives designed to mitigate highway-rail grade crossing collision risk and other components of user costs, including highway delay and queuing, air quality, and vehicle operating costs. The online application can be accessed via FRA's website.⁽⁴⁷⁾

The GradeDec is intended to assist State and local transportation planners in identifying the most efficient grade crossing investment strategies. The GradeDec modeling process can encourage public support for grade crossing strategies, including closure and separation, where project success often depends on getting the community involved in the early planning stages. The GradeDec computes model output using a range of values for many of the model inputs. This process allows individual stakeholders to influence how different investment options are weighed and evaluated.

The GradeDec implements the corridor approach to reducing collision risk that was developed as part of the Transportation Equity Act for the 21^st Century's Next-Generation High-Speed Rail Program (TEA-21, 1998, PL, 105-178). This approach can be an effective means of reducing the overall capital costs involved in constructing facilities for high-speed passenger rail service (at speeds between 111 and 125 mph), where grade crossing hazards and mitigation measures can be a major cost factor.

The corridor approach can be used to demonstrate that acceptable levels of collision risk have been reached for all rail corridors, train types, and speeds. For example, exceptions to the proposed federal rule mandating whistle-sounding at all highway-rail grade crossings can be made by showing that appropriate safety measures have been taken to mitigate the additional risk otherwise presented by trains not sounding their horns.

The GradeDec uses simulation methods to analyze project risk and generate probability ranges for each model output, including B/C ratios and net present value. The software also analyzes the sensitivity of project risk to GradeDec 2000 model inputs to inform users which factors have the greatest impact on project risk.⁽⁴⁸⁾

MUTCD Interpretations, Experimentation, Changes, and Interim Approvals

As technology and research continue to progress, updates to guidance and standards outlined in this Handbook, as well as the MUTCD, may be required. The FHWA periodically updates the MUTCD; however, updates to the document must go through a federal "rulemaking" process which requires posting the document in a Notice of Proposed Action (NPA) and addressing comments received before posting the revised document as a "Final Rule." A number of years may be required to provide a full update to the MUTCD.

The 2009 MUTCD with revisions 1 and 2 is available at https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/pdf_index.htm.

It should be noted that a "hotlinks" PDF version of the MUTCD which contains the most current updates to the MUTCD providing links to official interpretations, corrections to known errors, and other external documents is available at https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/hotlinksfeatures.htm.

During the intervening period between MUTCD updates, FHWA may provide "Interpretations" or "Interim Approvals" and practitioners may petition FHWA to conduct "Experimentation" for a new treatment following procedures presented in Section 1A.10 of the MUTCD

• Interpretations–Practitioners can request FHWA to clarify the intent of MUTCD provisions by formally requesting an official "Interpretation."
• Interim Approvals–Section 1A.10 of the MUTCD contains a provision authorizing the FHWA to issue Interim Approvals. Such approvals allow the interim use (pending official rulemaking) of a new traffic control device, a revision to the application or manner of use of an existing traffic control device, or a provision not specifically described in the MUTCD. Interim Approvals are considered by the FHWA Office of Transportation Operations based on the results of successful experimentation, studies, or research, and an intention to place the new or revised device into a future rulemaking process for MUTCD revisions.
• Experimentation–Experimentation provides a means for a practitioner to install and evaluate a new device. Although experimentation is a time-consuming process which requires installation of testing and potentially removal of a trial device, it does provide an opportunity to establish new treatments.

Practitioners should be aware of the following:

• Design, application, and placement of traffic control devices other than those adopted in this Handbook should be prohibited unless the provisions provided in Section 1A.10 are followed.
• Except as provided in Paragraph 4, of Section 1A.10, requests for any interpretation, permission to experiment, interim approval, or change should be submitted electronically to FHWA, Office of Transportation Operations, MUTCD team, at the following e-mail address: MUTCDofficialrequest@dot.gov