A NEW MIXED TRAFFIC SCENARIO: INTERACTION OF INTERNAL COMBUSTION VEHICLES AND ELECTRIC VEHICLES. A CASE STUDY FOR ADAPTIVE CRUISECONTROL (ACC) ON FREEWAY BOTTLENECK CAPACITY

Fully electric vehicles (EVs) have gained significant popularity and countries such as Norway are leading the world with over 90% EV market share in new car sales. However, older internal combustion engine (ICE) powered vehicles currently on today’s roads are expected to continue to operate until the end of their life cycle. As a result, a mixed vehicle fleet is expected to persist in the coming decade. Unfortunately, there has been an underlying assumption that the traditional internal combustion vehicles are expected to exhibit the same driving behavior when electrified vehicles are introduced in the mixed traffic fleet. Unlike ICE powered vehicles, EVs deliver immediate and strong deceleration via regenerative braking, and this could cause disturbances when the less capable ICE vehicles are following. These differences in driving dynamics may translate to substantial impacts to roadway capacity, especially when mixed with human driven ICE powered vehicles. Although ACC equipped EVs can adopt shorter headways and react quickly to speed changes, potentially improving roadway capacity, our empirically validated simulation study on ACC with ICE and electric powertrain suggestion that the increase in market penetration of EVs could result in greater capacity but mostly at higher EV market penetrations, because EVs mostly interact with other EVs and there would not be many ICE vehicles following EVs undergoing rapid regenerative braking. Conversely, at low market penetrations, there are numerous ICE vehicles interacting with a few EVs that undergo rapid deceleration, causing disturbances and negating the potential capacity benefit of EVs.