Are shared electric scooters competing with buses? a case study in Indianapolis

Shared e-scooter systems have been growing rapidly in many cities as a potential sustainable transportation mode. However, whether shared e-scooters compete with or complement existing public transportation is still unclear. This study proposes a modeling framework to identify the potential impacts of e-scooter trips on the existing bus system, considering the spatiotemporal availability of bus service. The impact of the potentially competing trips on transit ridership can then be verified using Difference-in-Differences models. The framework is applied to Indianapolis, Indiana as a case study. Our results show that about 27% of e-scooter trips could potentially compete with bus system and they are concentrated in downtown. The potential competing relationship can also lead to a bus ridership reduction. The complementary trips (29%) are mainly located outside of downtown where the bus coverage is low. Repositioning e-scooters to areas with limited bus service can better promote synergistic relationship between the two systems