USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Site Notification

Site Notification

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Public Roads - Spring 2019

Spring 2019
Issue No:
Vol. 83 No. 1
Publication Number:
Table of Contents

Setting a Course to Interoperability

by Kate Hartman, Deborah Curtis, Edward Fok, and Govindarajan Vadakpat

USDOT successfully demonstrated the ability to operate connected vehicles cross-site, over-the-air among six participating vendors from three pilot sites.

wal1 (1).jpg
A connected vehicle equipped with an onboard unit receives a forward collision warning alert from a stationary vehicle in the same lane of a controlled test track during the USDOT interoperability test at the Turner-Fairbank Highway Research Center in McLean, VA.

Connected vehicles have the potential to transform travel in the United States, helping to save lives, improve personal mobility, enhance economic productivity, and transform public agency operations. The U.S. Department of Transportation is leading research to move connected vehicles closer to wide-scale, national deployment.

To pave the way, one of USDOT's major goals is to test and demonstrate the current level of interoperability among still-maturing connected vehicle technologies. Interoperability ensures that devices including onboard units (devices installed in vehicles) and roadside units (devices deployed along the roadside by State and local agencies) from different manufacturers can exchange data and use the data in a consistent manner.

A watershed moment in the maturation of connected vehicles occurred at the Federal Highway Administration's Turner-Fairbank Highway Research Center (TFHRC) in June 2018. Through a collaborative effort, USDOT and three demonstration sites from the Connected Vehicle (CV) Pilot Deployment Program conducted an interoperability test. The test was the first of its kind involving devices from three deployment sites and six device vendors.

The goal of the test was to demonstrate whether onboard units installed in vehicles--and manufactured by different companies--from one CV pilot demonstration site could send and receive messages from onboard units and roadside units from other sites. More specifically, it looked at whether it is possible to send and receive messages between devices from different CV pilot sites in accordance with the key connected vehicle interfaces and standards.

Working with USDOT and its contractors, the CV pilot sites--New York City; Tampa, FL; and Wyoming--collaborated to harmonize the data elements and electronic messages that would be exchanged to make such interactions possible. This involved agreeing on a common set of data standards and establishing the security profiles, message protocol, and interpretations to enable converting the data being exchanged into the formats required for the various devices.

The interoperability test was the result of planning and collaboration facilitated through a series of biweekly technical roundtable meetings over the 6-month period leading up to the event. Coming into the test, participants were eager to see if all the preparation would pay off--and it did.

In total, USDOT and the CV pilot sites conducted more than 100 interoperability test runs for four test application-based cases--(1) forward collision warning, (2) intersection movement assist, (3) emergency electronic brake lights, and (4) reception of vehicle-to-infrastructure (V2I) signal phase and timing (SPaT) and MAP (mobile application part) messages to support red light violation warnings. Based on the testing, USDOT concluded that all vendors and CV pilot site deployment configurations are interoperable and can trigger warnings on each other's devices.

Tested Applications

Application Description
Forward Collision Warning An application where alerts are presented to the driver to help avoid or mitigate the severity of crashes into the rear end of other vehicles on the road. Forward collision warning responds to a direct and imminent threat ahead of the host vehicle.
Emergency Electronic Brake Lights An application where the driver is alerted to hard braking in the traffic stream ahead. This provides the driver with additional time to look for and assess situations developing ahead.
Intersection Movement Assist An application that warns the driver when it is not safe to enter an intersection--for example, when something is blocking the driver's view of opposing or crossing traffic. This application only functions when the involved vehicles are all vehicle-to-vehicle (V2V)-equipped.
Red Light Violation Warning An application that broadcasts signal phase and timing (SPaT) and other data to the invehicle device, enabling warnings for impending red light violations.


“Innovative testing like this helps provide confidence in the value of connectivity and that connected technologies will be interoperable nationwide,” says Bob Frey, director of planning and innovation at the Tampa Hillsborough Expressway Authority (THEA), which is leading the Tampa CV pilot deployment. “The testing proved that when standards are implemented correctly--from the beginning, even with a new technology--the ability for multiple manufacturers to successfully cooperate to provide a safer, more efficient road system for the public is possible.”

The Connected Vehicle Pilot Deployment Program

USDOT and its partners are working with State and local agencies to accelerate the deployment of this emerging technology, demonstrate its potential benefits, and help to overcome potential barriers and challenges along the way.

USDOT launched the CV Pilot Deployment Program in September 2015 to deploy, test, and operationalize cutting-edge mobile and roadside technologies and to enable multiple CV applications. Sponsored by the Intelligent Transportation Systems (ITS) Joint Program Office (JPO), USDOT awarded cooperative agreements to three agencies: the New York City Department of Transportation (NYCDOT), THEA, and the Wyoming Department of Transportation.

wal2 (1)
A THEA vehicle (white car) drives in an adjacent lane on a controlled test track at TFHRC without triggering a forward collision warning alert from a stationary NYCDOT vehicle.

During the first phase of the program, which lasted 12 months (September 2015 to August 2016), each site prepared a comprehensive deployment plan to address all of the proposed and other applications, security, operation and maintenance, procurement, and testing. In phase two (fall 2016 to spring 2019), the three sites designed, built, and tested the Nation's most complex and extensive deployment of integrated wireless invehicle, mobile device, and roadside technologies. In the third and current phase, the CV pilot sites are operating and maintaining their pilot deployment, assessing impacts, and evaluating deployment performance.

While each CV pilot site set out to address its specific local needs, the sites also have been working with USDOT to develop interoperable CV devices, equipment, and software that leverage industry standards.


Connected Vehicle Pilot Deployment Sites

New York City. The New York City pilot aims to improve the safety of travelers and pedestrians in the city through the deployment of V2V and V2I technologies. This objective directly aligns with the city's Vision Zero initiative, which seeks to reduce the number of fatalities and injuries resulting from traffic crashes.

New York City's deployment provides an ideal opportunity to evaluate connected vehicles and applications in tightly spaced intersections typical in a dense urban transportation system. It is set to be the largest CV deployment to date. The deployment will equip approximately 3,000 cabs, 700 Metropolitan Transportation Authority buses, 170 NYC Sanitation fleet delivery trucks, and more than 3,000 city-owned vehicles. In addition, approximately 340 signalized intersections are equipped with V2I technology. As a city bustling with pedestrians, the pilot also focuses on reducing vehicle-pedestrian conflicts through invehicle pedestrian warnings and an additional V2I/I2V project component that equips approximately 100 pedestrians with personal devices that assist them in safely crossing the street. For more information, visit

THEA. Tampa Hillsborough Expressway Authority (THEA) owns and operates the Selmon Expressway Reversible Express Lanes. The THEA pilot will deploy a variety of V2V and V2I applications to relieve congestion, reduce collisions, and prevent wrong way entry at the reversible express lanes' exit. THEA also plans to use CV technology to enhance pedestrian safety, speed up bus operations, and reduce conflicts between street cars, pedestrians, and passenger cars at locations with high volumes of mixed traffic.

The THEA CV Pilot will employ dedicated short-range communications (DSRC) to enable transmissions among approximately 1,600 cars, 10 buses, 10 trolleys, 500 pedestrians with smartphone applications, and approximately 40 roadside units along city streets. For more information, visit

Wyoming. Interstate 80 (I–80) in southern Wyoming is a major corridor for east-west freight movement, moving more than 32 million tons of freight per year. During winter seasons when wind speeds and wind gusts exceed 30 miles per hour (48 kilometers per hour) and 65 miles per hour (105 kilometers per hour) respectively, crash rates on I–80 can be 3 to 5 times as high as summer crash rates. This resulted in 200 truck blowovers and numerous road closures within 4 years.

The Wyoming CV pilot focuses on the needs of commercial vehicle operators and will develop applications that use V2I and V2V connectivity to support a flexible range of services such as advisories including roadside alerts, parking notifications, and dynamic travel guidance. The deployment is expected to reduce the number of blowover incidents and adverse weather-related incidents along the corridor to improve safety and reduce incident-related delays. The demonstration will include 75 roadside units that can receive and broadcast messages and approximately 400 vehicles consisting of a combination of fleet vehicles and commercial trucks with onboard units. For more information, visit

USDOT has a website with free CV resources for States, local agencies, and the public. The CV pilots' portal contains prerecorded webinars, presentations, and detail documents from each CV pilot site, for both phase 1 and phase 2 of the project. Resources range from the concept of operations, the safety management plan, and the system requirements specification to the application deployment plan and much more. In addition, the CV pilots' portal has a subsection focused on success stories and lessons learned. The portal is available at


What Is Interoperability?

Industry ITS standards support interoperability, which enables vehicles and the roadside infra-structure to exchange data in a consistent manner, regardless of the manufacturer of the vehicle, onboard unit, or roadside unit. Dozens of communities across the country are currently deploying or planning to deploy roadside units to enable data sharing and to support electronic message exchanges with vehicles. All elements in a CV environment--including onboard units, roadside units, and other ITS devices--must work together in a safe, trusted, interoperable, and efficient manner.

Adhering to ITS standards enables devices installed in vehicles from one manufacturer to communicate with other vehicles that may include devices from another manufacturer. From a practical perspective, interoperability ensures drivers using CVs have a safe, consistent experience from region to region--and eventually from coast to coast.

In a series of USDOT-facilitated technical roundtable meetings, the three CV pilot sites settled on an approach to conduct the interoperability test. USDOT and the CV pilot sites defined interoperability as: “A vehicle with an onboard unit from one of the three CV pilot sites is able to interact with onboard units and/or roadside units from the other sites in accordance with the key connected vehicle interfaces and standards.”

Planning for the Interoperability Test

With a clear definition of interoperability in place, the sites then worked with USDOT and its technical support contractor to develop a plan to conduct the interoperability test. The Connected Vehicle Pilots Phase 2 Interoperability Test: Test Plan (FHWA-JPO-18-691), available through USDOT's National Transportation Library, served as the official planning document for the interoperability test. The document describes the objectives, test equipment, test environment (or facility), roles and responsibilities, test preconditions, schedule, test cases, and test procedures necessary to conduct the interoperability test.

The scope of the interoperability test was to assess vehicle-to-vehicle (V2V) interactions between different sites' onboard units and V2I interactions between selected onboard units and roadside units. Onboard units (aftermarket equipment installed in the vehicles to conduct the test) included software that provided the capability to:

  • Receive basic safety messages (BSMs) transmitted by each of the other sites' onboard units.
  • Authenticate messages received from other vehicles' onboard units, as needed (such as when acting on the data or hearing a device for the first time).
  • Parse messages (such as decoding messages to the individual data element level).
  • Process messages (such as using the data as an input to applications, triggering responses according to the device's own application).

USDOT selected three common applications across the CV pilot sites to test interoperability: forward collision warning, emergency electronic brake lights, and intersection movement assist. In addition, researchers conducted a test to assess the ability of the onboard units from one CV pilot site to receive electronic messages containing the SPaT and MAP (the geometric intersection design) messages being broadcast from roadside units from another CV pilot site. New York City's onboard units and software also demonstrated the red light violation warning application.

Prior to the interoperability test, USDOT and the CV pilot sites conducted a test readiness review to evaluate key preconditions. The test readiness review ensured that all parties agreed to the test plan, all devices were available and ready for testing, all devices had been tested, and the test environment was ready to conduct the testing for each CV pilot site. USDOT reviewed progress toward test readiness during biweekly technical roundtable meetings. The test readiness review was a formal meeting where all stakeholders agreed that they were ready to show up to the test understanding their roles and responsibilities, and that all equipment was ready to support the interoperability testing efforts.


Testing occurred at TFHRC between June 26 and 28, 2018. The day before testing began served as a day of preparation and enabled the CV pilot teams to finalize installation of their devices in TFHRC-provided vehicles and configure and ensure operation of their applications and the roadside units.

Key to successful execution of the test was the support from FHWA TFHRC staff and its Saxton Transportation Operations Laboratory contractor who provided technical support to the CV pilot sites, the facility, and supporting equipment for the testing. This assistance included installing roadside units, installing onboard units from the sites in vehicles, and providing trained drivers to operate the vehicles during the interoperability test runs.

wal4 (1)
A Wyoming onboard unit installed in a TFHRC vehicle.

Each of the six TFHRC-provided vehicles had an onboard unit from one of the CV pilot site's vendors. In addition, the teams from the New York City and THEA sites each loaded their software on TFHRC-supplied roadside units. In total, the tests used two roadside units--both from the same vendor but with software from either New York City or THEA on a single device. All devices used for the tests were tied to the same commercial security credential management system (SCMS) and used test certificates from the SCMS to ensure trusted communication between onboard units and roadside units.

“Upon the successful conclusion of the interoperability testing with New York City and THEA, the WYDOT team developed confidence with the SCMS test certificates and messages,” says Vince Garcia, geographic information system/ITS program manager at WYDOT. “We are prepared to move forward with production enrollment and certificate use with our suite of applications used for heavy freight. These applications will help to improve safety during the blustery winters in Wyoming and along I–80 over some of the most rigorous terrain along the route.”

wal3 (1)
A THEA vehicle on a controlled test track at TFHRC approaches an intersection with a roadside unit.


wal5 (1).jpg
A THEA vehicle (white car) waits as it receives an intersection movement assist warning being triggered by a New York City vehicle (black car) at the TFHRC test track.

Over 3 days, the teams conducted more than 100 tests at TFHRC. They collected more than 10 GB of data for all tests and then sent the data to the cloud-based system--the Secure Data Commons (SDC)--where the data are available to support future research activities. Results of the testing indicated successful interoperable transfer of messages--BSMs, MAP, and SPaT--between the six vehicles from five different vendors. Four of the vendors used dedicated short-range communications (DSRC), and one used a combination of DSRC and satellite communications. In addition, each vendor demonstrated the successful transfer of messages between roadside units and the software installed to receive, process, and use electronic messages on each site's onboard units installed on the vehicles they will be using in their respective tests.

Lessons Learned

The team identified several valuable lessons learned from the interoperability test that may be beneficial for future testing activities.

A Wyoming vehicle (on right) receives a forward collision warning alert being triggered by a New York City vehicle with the other four vehicles driving by the adjacent lane on the test track.

Coordinate regularly in the months leading up to the test date. Coordination before the interoperability test enabled CV pilot sites, vendors, and stakeholders to work together, procure equipment, develop a schedule, and provide feedback. A critical facilitator for coordination was a biweekly technical roundtable. A clear definition of roles and responsibilities was important to support planning and execution of the test. Clearly identifying all roles and backups in the case of unexpected events is essential.

Coordinate with test sites to receive all equipment and software well in advance of conducting the test. The CV pilot sites shipped all testing equipment to TFHRC 2 weeks before testing. This amount of time enabled TFHRC to set up onboard units in designated vehicles and make sure the software was working as designed. It also provided time for representatives from CV pilot sites to verify the installations.

Schedule a full day for setup, checkout, and dry runs. Using the first full day to check equipment installation and ensure applications run as expected, among other things, was beneficial. CV pilot sites and vendors were able to do last-minute updates, study the test bed, and make changes to the test plan for successful execution.

Make conservative estimates for test runs. For planning purposes, the teams assumed 10 minutes per test run for the interoperability testing. However, this estimate accommodated for the test run and data collection activities. Some test runs and data collection activities took as little as 2 minutes to conduct, while others took more than 10 minutes. In general, use conservative estimates to account for variability of test runs.

Include a premeeting and set aside 20–30 minutes for dry runs before conducting individual tests. While running the individual tests, the teams found it beneficial to run through the test procedures for each application's test a few times to well inform drivers, vendors, and stakeholders and set expectations. In addition, schedule time at the end of each day to identify which tests need to be rerun and to discuss any issues the drivers and other individuals encountered during testing.

Have walkie-talkies to communicate with drivers, test leads, USDOT representatives, and others during test runs. Walkie-talkies were indispensable during the interoperability test. USDOT representatives were able to communicate the start time of each test with invehicle personnel as well as flaggers. The test director and other staff leading coordination of the testing activities also communicated end time for each test via walkie-talkies.

Moving Forward

Overall, the 3-day testing event was a major success that went above and beyond the event's original testing objectives, with time allotted on the last day for some impromptu tests. Results of the testing indicated successful transfer of messages between the six vehicles with devices from five different onboard unit vendors. In addition, equipment from New York City's and THEA's vendors demonstrated the successful transfer of messages between the site-configured roadside units and the sites' onboard units.

For more information, a video summarizing the interoperability test is available at

The results of the interoperability test are encouraging, but State and local agencies planning to deploy CVs cannot expect out-of-the-box plug and play interoperability. However, the tests show that organizing around current standards can produce a relatively high level of interoperability. More work remains to strengthen and improve standards, as well as bring more vendors, deployers, and USDOT together to build upon this important step.

The interoperability test was a major step forward. As the CV pilot sites move into their deployment phase, and dozens of State and local agencies deploy CVs across the country, continued collaboration is necessary to ensure that the systems are interoperable so that drivers have the same experience when using devices as they travel from coast to coast.

“It is essential to demonstrate interoperability among vendors' products by applying connected vehicle standards,” says Mohamad Talas, director of systems engineering at NYCDOT. “Interoperability will ensure successful expansion and sustainability of the deployment and will help New York City achieve its goal of improving safety. We are happy with the outcome of the test and hope the efforts will continue to further address more features and applications of this promising technology.”

Kate Hartman serves as the chief of research, evaluation, and program management in the ITS Joint Program Office at USDOT. She is the program manager for the CV Pilot Deployment Program. She holds a B.A. in economics from the University of Virginia and an M.B.A. from the University of South Dakota.

Deborah Curtis is a research transportation specialist at FHWA. She has more than 28 years of experience leading projects related to traffic signal systems, ITS, and, most recently, cooperative automation. She has a B.S. in civil engineering from West Virginia University.

Edward Fok is a transportation technology specialist at FHWA's Resource Center, where he focuses on assessing emergent technologies for opportunities and risk for surface transportation. He has B.S. degrees in mechanical engineering and electrical engineering.

Govindarajan Vadakpat is a research transportation specialist at FHWA, where he manages the THEA CV pilot. He holds a Ph.D. in civil engineering from Penn State. He is a professional traffic operations engineer and a licensed professional engineer in Maryland, Ohio, and Virginia.

For more information, see or contact Kate Hartman at 202–366–2742 or

The CV pilot interoperability test included participants from USDOT and its contractors, the CV pilot sites, connected vehicle device vendors, and others