California study finds cooperative adaptive cruise control reduced headways from 2.05 seconds to 0.80 seconds and increased flow from 1,400 to 3,000 vehicles per hour.

Simulation of adaptive and cooperative cruise control technologies at urban intersections.

Date Posted
04/23/2018
Identifier
2018-B01268
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Using Adaptive and Cooperative Adaptive Cruise Control to Maximize Throughput of Signalized Arterials

Summary Information

Traffic flow is the product of speed and density. Headways are inversely related to density: longer headways mean lower densities. Emerging automated cruise control technologies may reduce headways by factors of two or three compared to manual driving, enabling faster speeds at higher densities. This report investigates how the maximum acceleration and proportion of vehicles using adaptive cruise control (ACC) and cooperative adaptive cruise control (CACC) impacts throughput of given intersections.



Methodology



This study utilizes SUMO, an open source microscopic simulator of vehicle traffic. In most cases, two scenarios are simulated and discussed: free flow after an intersection and a second intersection 300 m after the first intersection. Additionally, simulation of a four-mile length arterial network in Arcadia, California is used to evaluate the performance of ACC and CACC vehicles. Mean travel time and standard deviation are used as performance measures. In this study, ACC is an autonomous technology, where a vehicle responds to its surroundings. CACC includes platooning capabilities with other CACC-equipped vehicles.

Findings

ACC and CACC vehicles reduced the queue sizes at all observed intersections, translating to more efficient flow through intersections. The following table summarizes the comparison:

 

Vehicle Class Headway (seconds) Flow (veh/hr) Headway (meters)
Manual
2.05
1,440
4
ACC
1.10
2,400
3
CACC
0.80
3,000
3

Vehicles with CACC can form platoons. At a 50 percent CACC penetration rate, the simulations found that platoons can increase intersection throughput by between 24 and 44 percent, depending on the proximity of the intersections. At a less than 30 percent CACC penetration rate, improvement over manual driving is equal to that of ACC vehicles.

Goal Areas
Results Type
Deployment Locations