Integrated Public Transportation System with Shared Autonomous Vehicles and Fixed-Route Transits: Dynamic Traffic Assignment-Based Model with Multi-Objective Optimization

Abstract

The shared autonomous vehicle (SAV) system is considered as an efficient transportation mode in the future. In the literature, optimization of SAV systems has been extensively studied. However, SAV systems could bring greater social benefits if we could use them with existing public transportation systems, such as bus rapid transit (BRT), in an integrated manner. This study proposes a model of SAV-BRT system, an integrated system that takes advantage of the flexibility of SAVs and the mass transport capability of BRT. The proposed model is based on a dynamic traffic assignment model so that it captures important features of SAV-BRT system, such as endogenous traffic congestion, detour and waiting of SAVs, BRT’s dynamic scheduling. The model is formulated as a multi-objective optimization problem so that trade-off relations regarding the system’s performance can be explicitly analyzed. The behavior of the model is investigated by conducting numerical experiments based on actual travel data obtained from an urban area in Japan. As a result, we confirmed that the model behaves reasonably, and several insights on SAV-BRT systems have been obtained.