Modelling the Impacts of En-Route Ride-Pooling Service in a Mixed Pooling and Non-Pooling Market

En-route ride-pooling services, e.g. Didi Pinche, UberPool, have been considered a promising way to alleviate traffic congestion during rush hours. Yet in reality, its market share is still small compared to non-pooling service. For a ride-hailing platform that provides both en-route pooling and non-pooling services, this paper endeavors to answer under what circumstance would it have incentive to encourage ride-pooling, and whether drivers, riders, the platform and the society can simultaneously benefit from the introduction of en-route ride-pooling service. We propose an aggregate model to characterize the equilibrium of a ride-hailing market where a platform operates a fleet of vehicles to provide en-route pooling and non-pooling services. The model captures the complex interactions among riders' mode choices between pooling and non-pooling, the waiting times of pooling and non-pooling users, the pairing probability and the expected detour time of pooling users, the matching rates of cruising and halfly occupied vehicles with different types of riders, and the numbers of cruising, halfly occupied and fully occupied vehicles at each instant. Based on the model, we theoretically reveal the impacts of the total ride-hailing demand, vehicle fleet size, and the platform's pricing and vehicle dispatching strategies on the market equilibrium performance through partial derivative-based sensitivity analysis, and establish conditions under which the introduction of en-route ride-pooling service improves platform profit, driver income, rider utility and social welfare.