University of California Institute of Transportation Studies

In an ideal world, all cars along a congested roadway would travel at the same constant average speed; however, this is hardly the case. As soon as one driver brakes, trailing cars must also brake to compensate, leading to “stop and go” traffic waves. This unnecessary braking and accelerating increases fuel consumption (and greenhouse gas emissions) by as much as 67 percent.1 Fortunately, automated vehicles (AVs) — even Level 2 AVs2 which are commercially available today — have the potential to mitigate this problem. By accelerating less than a human would, an AV with flow smoothing technology is able to smooth out a traffic wave, eventually leading to free-flowing traffic (See Figure 1). To demonstrate the potential of flow smoothing on reducing greenhouse gas emissions, researchers at UC Berkeley used a calibrated model of the I-210 freeway in Los Angeles to simulate and measure the effect of deploying different percentages (10%, 20%, 30%) of flow-smoothing AVs on the average miles per gallon (MPG) of non-AVs in the traffic system.