Environmental Impact Evaluation of Connected Vehicle End-of-Ramp Warning in Tampa, Florida Estimated That Annual Carbon Dioxide Emissions Were 240 Kilograms Lower in the Post-Deployment Period.

Comparison of Pre- and Post-Deployment Period Data from Connected Vehicle Pilot Calculated Emissions Impacts Associated with Reduced Vehicle Idling, Though Pandemic Factors Affected Results.

Date Posted

Connected Vehicle Pilot Deployment Program Independent Evaluation: Environmental Impact Assessment—Tampa (THEA)

Summary Information

Connected vehicle (CV) technologies utilize advanced wireless communications to share information between vehicles, devices, and the infrastructure to enable potential safety improvements and mobility enhancements. An independent assessment was conducted to evaluate the environmental and mobility impacts associated with the Tampa Hillsborough Expressway Authority (THEA) CV Pilot Deployment (CVPD), as a part of the USDOT CVPD program. Beginning in 2018, over 1,000 vehicles in Tampa, Florida were equipped with aftermarket CV devices that could issue warnings to the vehicle operators. The independent evaluator for the project used available data from the deployment in Tampa to estimate fuel consumption differences and associated emissions. However, it is important to note that estimates should be interpreted with caution, as fewer vehicles entered the study area due to the major demand shift related to the COVID-19 pandemic.


The results from a deployed use case, congestion reduction and collision avoidance due to queuing on the exit ramp from the Reversible Express Lanes (REL) during the morning peak, were used for the evaluation. Use Case 1 deployed three specific CV applications: Electronic Emergency Brake Light (EEBL), End of Ramp Deceleration Warning (ERDW), and Forward Collision Warning (FCW). An existing methodology from Argonne National Lab was adopted for use in the evaluation, to estimate the fuel reduction benefits in this use case based on the reduction in observed idle time. Then, a methodology developed by the U.S. Environmental Protection Agency (EPA) was applied to calculate an equivalent greenhouse gas emission reduction, based on the estimated reduction in fuel consumption.


  • The results showed that on average, in the pre-deployment period, vehicles spent 78.38 minutes idling during the peak period. In the post-deployment period, vehicles spent 55.69 minutes idling per peak period. The total amount of fuel consumed by equipped vehicles idling on the REL dropped from 0.36 gallons in the pre-deployment period to 0.26 gallons in the post-deployment period, translating into a reduction in fuel consumption of 0.1 gallons (or 28 percent) per peak period, or approximately 27 gallons per year.
  • Using the EPA’s Greenhouse Emissions Calculator, the independent evaluator estimated a reduction of 240 kilograms of Carbon Dioxide emissions per year. This reduction was based on the estimated reductions in fuel consumed while idling resulting from the ERDW deployed in Use Case 1.
  • The evaluation also noted that this emission reduction was also associated with the pandemic’s reduction in the number of equipped vehicles during the post-deployment period compared to the pre-deployment period.
Results Type
Deployment Locations