Evaluating the safety impact of employing a dedicated lane for connected and autonomous vehicles on a motorway section

Abstract

This study aims to analyse the safety impact of employing a dedicated lane during the transition period between manual and autonomous driving. In particular, it (1) identifies the optimal strategy for using a dedicated lane for connected and autonomous vehicles (CAVs) according to the safety perspective, and (2) evaluates the safety improvement caused by employing a dedicated lane while penetrating different levels of automation on the road. Using a microsimulation platform (Aimsun’s next), about 20 km of motorway segment is modelled and configured with/without a dedicated lane; with mandatory use for CAVs when the penetration rate is up to 30% and optional use for more than 30%. The safety of several scenarios of mixed fleets of CAV are evaluated using the Surrogate Safety Assessment Model tool and compared at both modelled configurations (with/without a dedicated lane) under both traffic conditions (free flow and congestion). The optimal strategy to employ a dedicated lane at light volumes is when the penetration rate of high levels of automation is above 55% (optional policy) while employing a dedicated lane is always appreciable at congestion condition.