Office of Safety and Operations 

Research and Development 

1

Facilitating communication 

between work zone 

infrastructure and vehicles, 

enabling them to adapt their routes and 

speeds for safe navigation through the work 

zone, thereby reducing the probability of 

accidents. Safety was further improved by 

utilizing a traffic controller instead of a 

flagger to regulate bidirectional traffic in the 

open lane of a two-lane arterial road when a 

lane is closed due to road work. The traffic 

signal controller provides the signal phase 

and timing (SPaT) data to the vehicles for 

safe navigation.

Work Zone Management for Light Vehicles Using Cooperative 

Driving Automation (CDA) 

Work zone fatalities have increased 61 percent since 2013.(1) CDA can help decrease these fatalities and support 

safer automated vehicle (AV) operations with infrastructure-communicating work zone configurations and with 

restrictions to AVs before they reach the work zone. These strategies will increase the AVs’ situational awareness 

and plan their motion. Due to the implementation of temporary traffic controls, the work zones pose a challenge 

for automated driving systems to navigate, as some of these systems may be using previously created maps of 

roads for their driving environment. Work zones often change lane configurations, disrupt lane markings, and 

obscure other vehicles and pedestrians, which can challenge AV perception and navigation systems. 

BENEFITS TO TRANSPORTATION 

© Getty Images Plus.

Enabling autonomous 

vehicles to update their 

internal maps with real-time 

work zone configurations and 

react proactively to evolving 

driving conditions by adjusting their 

trajectories to optimize traffic flow. This 

technology mitigates congestion at work 

zone entrances and exits and potentially 

provides some fuel usage benefits.

IMPROVED SAFETY

IMPROVED MOBILITY

Source: Federal Highway Administration (FHWA).

Figure 1. Image. Traffic control requests (TCRs) and traffic control messages 

(TCMs) communicated to and from vehicles and infrastructure.

EVALUATION OF THE CONCEPT

The light-vehicle work zone scenario was designed to test 

how CDA can improve work zone safety on a two-lane 

arterial road with one lane closed due to a work zone and 

with traffic alternating directions in the open lane. In this 

scenario (figure 1), a vehicle equipped with CARMA 

PlatformSM(2) approaches the work zone. A fixed-timed traffic 

light controls traffic in the open lane, replacing a flagger.
https://highways.dot.gov/research/

2

The work zone configuration was communicated to the vehicle through custom-made TCMs, including signal 

group identifiers, so that the vehicle could identify SPaT(3) messages from the appropriate traffic signal 

positioned at the work zone. Using the received TCMs, the vehicle updated its internal map to match the work 

zone configuration, and the vehicle proceeded past the traffic signal properly by processing the received SPaT 

messages. This process allowed the vehicle to reroute through the work zone and respond appropriately to 

the traffic signals. This technology is important because it communicates updated traffic rules to the vehicle, 

allowing the vehicle to operate safely. 

USE CASE ARCHITECTURE

This scenario uses the following parts of the CARMASM ecosystem: CARMA CloudSM,

(4) CARMA Platform,(2) and 

Vehicle-to-Everything (V2X) Hub.(5) The scenario also uses the work zone data exchange tool,(6) creates work 

zone configurations in the online work zone data exchange interface, marks lane closures, and marks the 

location of workers. These configurations can then be disseminated by the work zone data exchange to inform 

other entities (such as AVs) and systems (such as CARMA Cloud) about nearby upcoming work zones. In this 

case, CARMA Cloud regularly requests all work zone events from the work zone data exchange tool and 

generates the appropriate TCMs. Once in CARMA Cloud, these messages can be requested by AVs. The AVs can 

then use the information in those messages to adapt their routes based on the configuration of the work 

zones they encounter. 

WORK ZONE MANAGEMENT FOR LIGHT VEHICLES USING CDA

Source: FHWA.

Figure 2. Image. Work zone information data flow.(2, 4, 5, 6)
3

Figure 2 depicts a vehicle equipped with CARMA Platform(2) approaching a work zone. The vehicle then sends 

TCR messages to a roadside unit (RSU). Next, this unit forwards the request to CARMA Cloud(4) via the V2X Hub.(5)

CARMA Cloud sends back the latest work zone information it received from the work zone data exchange(6) in 

the form of TCMs. These TCMs are then forwarded to the RSU by the V2X Hub. The RSU then sends these TCMs 

to the vehicle. Next, the vehicle uses these TCMs to adjust its route through the work zone. Additionally, a 

traffic signal sends its SPaT(3) messages to the V2X Hub, which forwards the messages to the RSU so that they 

can be broadcast to the vehicle. The vehicle processes these received SPaT messages and updates its 

trajectory to either stop at the associated stop bar or proceed past it.

RESULTS AND LESSONS LEARNED

Independent evaluators from the U.S. Department of Transportation Volpe National Transportation Systems 

Center tested this system, in the planned scenario, to confirm that the following testing criteria were met: 

 The vehicle could respond appropriately to SPaT(3) messages received from a traffic signal equipped with

V2X Hub(5) and an RSU. Acceptable responses by the AV include continuing past the traffic signal in the

event of a green light or slowing to a stop and waiting until the signal changes to green before proceeding.

 The vehicle could follow a path that matches the lane geometry described in the TCMs created in CARMA

Cloud(4) and broadcasted by the V2X Hub, when traveling through the work zone.

 The vehicle could maintain a normal speed limit of 20 mph when not within the work zone, and a reduced

speed limit of 15 mph when in the work zone, as described in the TCMs created in CARMA Cloud and

broadcasted by the V2X Hub.

Across all test runs, the systems involved correctly communicated information to each other. More specifically, 

the V2X Hub-equipped RSU with a connection to CARMA Cloud successfully broadcasted both TCMs and SPaT 

messages, and the AV received and processed both message types. This outcome allowed the AV to respond 

appropriately to the traffic signals and navigate the work zone. 

CONCLUSIONS

The test case demonstrated the practicality of CDA-enabled vehicles receiving notifications about alterations 

due to temporary traffic control in the presence of a work zone. These messages enable the vehicles to navigate 

through the work area safely and precisely. Future research could potentially focus on the following areas: 

WORK ZONE MANAGEMENT FOR LIGHT VEHICLES USING CDA

Test using cellular and cellular 

vehicle-to-everything.

Collaborate with stakeholders to 

determine best practices and 

potential standard updates.

Test in simulation at scale to 

identify and evaluate benefits 

and impacts. 
© Getty Images Plus.

TITLE OF TECHBRIEF

4

For more information, please contact the CDA Program at CDA@dot.gov

FHWA-HRT-24-028

HRSO-40/12-23(200)E

References

1 Work Zone BarriersTM. 2023. “Work Zone Fatalities, Injuries, & Crashes” (web page). https://www.workzonebarriers.com/

work-zone-crash-facts.html#%3A~%3Atext%3DIn%202021%2C%20over%20105%2C000%20work%2Cand%20954%20work

%20zone%20fatalities, last accessed September 21, 2023.

2 FHWA. n.d. “carma-platform” (software and configuration files in GitHub repository). https://github.com/usdot-fhwa-stol/carmaplatform, last accessed October 23, 2023.

3 Intelligent Transportation Systems Joint Program Office. n.d. Signal Phase and Timing (SPaT). Washington, DC: USDOT. 

https://www.itskrs.its.dot.gov/sites/default/files/doc/07_SPaT%20Challenge_FINAL%20508%20VERSION_06_23_21.pdf, last 

accessed October 24, 2023.

4 FHWA. n.d. “carma-cloud” (software and configuration files in GitHub repository). https://github.com/usdot-fhwa-stol/carmacloud/tree/develop/yield_plugin, last accessed October 23, 2023.

5 FHWA. 2021. Vehicle-to-Everything (V2X) Hub: Open-Source Connected Vehicle (CV) Software. Publication No. FHWA-HRT-22-047. 

Washington, DC: Federal Highway Administration.

6 U.S. Department of Transportation. 2023. “Work Zone Exchange (WZDx)” (web page). https://www.transportation.gov/av/data/

wzdx, last accessed November 21, 2023.

WORK ZONE MANAGEMENT FOR LIGHT VEHICLES USING CDA

Recommended citation: Federal Highway Administration. Work Zone Management for Light Vehicles 

Using Cooperative Driving Automation (CDA) (Washington, DC: 2023) https://doi.org/10.21949/1521468