Assessing the impact of shared and autonomous vehicles on urban traffic

Abstract

New developments in the automotive world have the power to change mobility, but because of high uncertainties, municipalities are adopting a wait-and-see attitude. Nonetheless, autonomous, connected and shared vehicle technologies are in a far stage of development and it is only a matter of time before AVs and SAVs enter urban traffic. This research aims to provide insights in the congestion effects of AVs and SAVs on urban traffic, focusing on the differences in microscopic behaviour from conventional cars, and to investigate which easy-to-implement solutions a municipality could apply to facilitate the new mix of traffic. This was researched by performing a simulation study, using the traffic simulation package Vissim and a case study of a network in The Hague during the morning peak in 2040. Several AV and SAV market penetration scenarios were tested. Additionally, two network designs were implemented: dedicated lanes for SAVs and kiss & ride (K&R)-facilities. From the results, it was clear that AVs were able to relieve congestion by increasing road capacity and providing a more smooth traffic flow. SAVs, however, caused higher levels of congestion by stopping at the curbside to drop off passengers, forming bottlenecks for other road users, and by circulating on the network using low capacity links. The dedicated lanes design was unsuccessful at reducing this congestion caused by SAVs. The K&R design, however, was successful at reducing delays, but only for SAV penetration rates of higher than 25%. The advice for municipalities is to closely monitor the situation and to account for AVs and SAVs in each new infrastructural project.