A structured flexible transit system for low demand areas

Public transit structure is traditionally designed to contain fixed bus routes and predetermined bus stations. This paper presents an alternative flexible‐route transit system, in which each bus is allowed to travel across a predetermined area to serve passengers, while these bus service areas collectively form a hybrid ‘grand’ structure that resembles hub‐and‐spoke and grid networks. We analyze the agency and user cost components of this proposed system in idealized square cities and seek the optimum network layout, service area of each bus, and bus headway, to minimize the total system cost. We compare the performance of the proposed transit system with those of comparable systems (e.g., fixed‐route transit network and taxi service), and show how each system is advantageous under certain passenger demand levels. It is found out that under low‐to‐moderate demand levels, the proposed flexible‐route system tends to have the lowest system cost.