Eco-Approach and Departure (EAD) techniques for connected vehicles can save six percent energy for trip segments within range of DSRC enabled signal controllers.

Reserach findings from the Exploratory Advanced Research (EAR) program.

Date Posted

Eco-Approach and Departure (EAD) Application for Actuated Signals in Real-World Traffic

Summary Information

This research evaluated the performance Eco-Approach and Departure (EAD) applications on a real-world corridor supporting Dedicated Short Range Communications (DSRC) and connected vehicles in El Camino Real, California in November 2015.


A 2008 Nissan Altima research test vehicle was set up for field testing. A real-time automotive radar system was installed on its front end to detect headways and relative speeds of leading vehicles. An on-board system was designed to receive SPaT messages (in compliance with SAE J2735 standard) derived from signal state datagrams transmitted from Caltrans 2070 intersection signal controllers using AB3418 protocol broadcast over DSRC at 10 Hz. The test vehicle used an onboard computer to process GPS referencing data, incoming SPaT and GID messages, and vehicle dynamics data (instantaneous speed and RPM). Based on the GPS data and a custom map-matching algorithm, the vehicle’s distance-to-intersection was estimated with consideration given to vehicle headways and then a recommended vehicle trajectory was calculated using the EAD algorithm. Recommended speeds were delivered to the driver using a 7-inch automotive-grade display.

Field tests were conducted during peak hour traffic conditions on a 1.7 mile section of El Camino Real corridor having 10 intersections operated by DSRC enabled signal controllers . Performance was evaluated to assess system impacts in terms of energy savings and emissions reduction.


The EAD system effectively reduced the idling or near-idling cases by 22 percent. The EAD system saved two percent energy for all trips, and six percent energy for EAD activated trip segments. The proposed system also significantly reduced air pollutant emissions (7 percent of Carbon monoxide, 18 percent of hydrocarbons, and 13 percent of Nitrogen oxides) for all trips.