Table 8.

Summary of the studies investigating the impact of AVs on the environment

Study	Results
Barth, Boriboonsomsin, and Wu (2014) [35]	This research studied the impact of AVs on energy consumption and emissions using the generalized energy or emission versus speed curve for typical traffic which state that the lowest emissions level and the lowest fuel consumption level occur at a speed range between 35 and 55 mph. Results shows that AVs can reduce emissions and energy through three main factors: first, reducing congestion (by increasing the capacity and reducing collision rate) and in turn increase the speed. Second, vehicle platoons which reduce the aerodynamic drag forces on vehicles as a separation of 4 m can achieve 10–15% energy saving. Third, traffic smoothing effect that reduces the sharp stop and go. The smooth operating can reduce the fuel consumption by 15%
Fagnant and Kockelman (2014) [18]	The simulation model for Austin, Texas, USA, shows 34% reduction in the CO2 emissions and 49% reduction in the volatile organic compounds (VOC)
Miller and Heard (2016) [36]	Results shows that AVs can enhance the fuel economy dramatically due to: platooning effect, reduction in collisions, and reduction in congestion due to the optimized vehicle operation as AVs will allow for the application of system optimal traffic assignment which reduces the total travel time in the entire network. On the other hand, reducing collisions and congestion might increase the travel speeds, which means higher emission
Kockelman and Clements (2017) [38]	This study estimated that AV platooning can improve safety and reduce the fuel consumption by 15%
Securing America’s Future Energy (SAFE) (2018) [42]	Results of this study show that AVs can reduce the fuel consumed by 20% with an economic benefit of 3.4$ billion per year. Additionally, AVs can substantially reduce America’s reliance on oil with a social benefit of 58 $ billion by 2050