Snowplow Signal Priority Pilot Project

About the Project

CDOT Region 1, which covers eight counties in Central Colorado including Denver and the surrounding metropolitan area, is carrying out the Snowplow Signal Priority (SPSP) pilot project, aimed at creating a safer and more efficient environment for snow plows conducting plowing operations along signalized state highways.

CDOT maintenance crews are responsible for plowing all interstates, US highways, and state highways in Colorado totaling more than one million lane miles in snow removal each year in the Denver Metro Area alone. A portion of those lane miles includes state highways that have signalized intersections including CO 121 (Wadsworth Boulevard) and CO 88 (Arapahoe Road). Currently, CDOT snow plows stop at red light signals along with the rest of the traveling public.

The SPSP pilot project will utilize Connected Vehicle (CV) technology that will create vehicle to infrastructure and infrastructure to vehicle (V2I/I2V) communication to enable CDOT snow plows to improve efficiency of snow clearance operations. In this case, the infrastructure includes the traffic signal cabinet. The technology will allocate an early green or extend the green time at the signal when a CDOT snowplow is detected at the intersection, which in turn will expedite plowing efforts along signalized state highways and lead to a safer environment for both plow drivers and motorists.

Region 1 Snowplow Signal Priority Project Logo

The SPSP pilot project will implement new innovations and technologies in these corridors and will provide the following benefits:

  • Enhance safety
  • Reduce time to plow pavement
  • Improve traffic flow along the identified corridors during and after snow removal

The technology includes an on-board unit (OBU) inside of CDOT snow plows that can communicate with the Road Side Unit (RSU) via radio signal at the intersections, and the RSU will communicate with the signal controller to initiate the change from a red to green signal. This allows snowplows to request extended green or early green signal phases. Thorough testing will be conducted at the identified intersections during the winter of 2020/2021 before the technology can be expanded onto other intersections along Wadsworth Boulevard and Arapahoe Road in winter of 2021/2022.

The pilot project funding is made possible through a grant from the Federal Highway Administration's (FHWA) Accelerated Innovation Deployment (AID) Demonstration program. You can learn more about this in the FHWA INNOVATOR Newsletter from May/June 2020.

Project Location

The Snowplow Signal Priority Pilot Project kicked off in winter 2020-21, starting with up to three signalized intersections along Wadsworth Boulevard in Jefferson County and Arapahoe Road in Arapahoe County. These corridors have a high level of readiness for this project as CDOT has been investing in traffic signal communications, controller, and cabinet upgrades in both of these corridors.

Project map for the Snowplow Signal Priority project

Arapahoe Road Map

Wadsworth Boulevard Map


Bench testing in the lab

  • The Region 1 SPSP team has explored various methodologies that enable the most efficient communication between the CV (connected vehicle) and ITS (intelligent transportation systems) infrastructure. After thorough bench testing, the project team chose an option that is more reliable and less complex.
  • The bench test process was conducted in the lab environment between October 2020 and June 2021 and tested compatibility of the traffic signal controller, RSU (road side unit) and OBU (on board unit). The photo below shows a bench test taking place. 
  • During the bench test, the project team conducted several test cases to ensure the communication between the CV and ITS infrastructure is consistent, reliable, and secured. At the end of this bench testing phase, the project team had a vision of how to test these CV devices in the field at the three intersections along Wadsworth Boulevard (Peakview Drive, Coal Mine Avenue, and Columbine Drive) during the next phase, the pilot study. 
    Lab Tests.png

Installation and testing of pilot study units out in the field

  • Before full deployment of the connected vehicle (CV) infrastructure, the project team will conduct a pilot study out in the field to
    ensure the devices are functional as expected. As shown in the photo below, the project team installed the Road Side Units (RSU) at three different intersections along Wadsworth Boulevard (Peakview Drive, Coal Mine Avenue, and Columbine Drive). During this pilot study phase, these devices will be turned on 24-7 to test for long-term reliable communications, safety concerns, and data accuracy. The project team anticipates completing the pilot study by the fall of 2021. 

CDOT crews installing Snowplow Signal Priority Pilot Project technology along Wadsworth Boulevard

Evaluation of pilot study results

  • CDOT will analyze and evaluate the data and results that are being collected during the pilot study and move forward with the full implementation of the technology.