Green Cooperative Adaptive Control Systems in the Vicinity of Signalized Intersections: Final Report
Using advanced signal-change information, information about queued vehicles at signalized intersections and speed and headway of the lead-vehicles, this vehicle trajectory optimization tool predicts the future constraints that the vehicle will be subject to and generates a speed profile that is fuel-optimal.
The effectiveness of the cruise control system was tested by running 2100 agent-based simulations in a MATLAB environment. The combination of controller-agents, ECACC-agents and driver-agents were used specifically so that they act independently, while also interacting with each other. The communication between the agents followed the Connected Vehicles (CV) standards being set by the Society of Automotive Engineers (SAE) J2735 messages.
The intersection of South Main Street and Washington Street in downtown Blacksburg, Virginia was used for modeling. A total of 30 different calibrated vehicles that corresponded to the five top-sold vehicles of six different EPA categories (compact cars, mid-size cars, full-size cars, sport utility vehicles, mini passenger vans and light-duty trucks) were used. The vehicle parameters pertain to 2011 base models of all vehicles. The DSRC communication range was assumed to be 200 m as recommended by the SAE. The 2100 simulation runs included a total of five vehicle offset times (2, 4, 6, 8 and 10 s) and seven different approach speeds (30, 40, 50, 60, 70, 80 and 90 km/h). The "time to green" values were computed prior to simulations based on approach speeds and distances to the intersection.
Calibrated fuel-consumption models were used, both in generating the optimized speed profile and also in comparing the measures of effectiveness between the baseline case and the test cases.
- The average fuel reduction for the overall simulation was between 27 and 32 percent. The fuel reduction was higher for low volumes and decreased as the traffic volumes increased.
- Fuel savings are proportional to the vehicle’s approach speed. For example, fuel savings of 5 percent were achieved for approach speeds of 30 km/h whereas fuel savings of 23 percent were achieved when the vehicle approach speed was 90 km/h.
- Possible fuel savings reduce with increasing vehicle delay times. While a 2-second vehicle delay yielded an average benefit of 17.5 percent fuel savings, a 10-second delay only yielded 13.3 percent fuel savings within the vicinity of intersections.
- Compact cars benefitted equally to Light-Duty Trucks (LDTs) when they used the ECACC system. However, it should be noted that the absolute savings are higher for LDTs.