Flexible Transit Service Reduced Travelers’ Generalized Costs by 67.7 Percent Compared to Fixed-Route Bus in Two Service Areas in Seattle.
Simulation Study Comparing Flexible Transit to Other Modes Found User Cost Benefits, Despite Higher Operator Costs.
Seattle, Washington, United States
Incorporating Mobility on Demand into Public Transit in Suburban Areas: A Comparative Evaluation of Cost-Effectiveness
Summary Information
Traditional fixed-route transit services tend to be inefficient in low-density areas due to limited and dispersed demand for service. Transit agencies have begun experimenting with Transit Incorporating Mobility-on-Demand (TIMOD) programs specifically to target and supplement the first-mile, last-mile connections, one of the main barriers to transit ridership in low density areas. This study evaluated the cost-effectiveness of TIMOD compared to fixed-route bus transit, driving alone, and commercial ride-hailing services using simulation with real-world data from the Metro Flex program, a TIMOD service in the Seattle area. Trip data from Metro Flex for May 2023 were used in the simulations to compare generalized costs for various travel modes.
METHODOLOGY
The study collected and analyzed trip data from Metro Flex, while considering variations in users' socioeconomic backgrounds and land use factors. The study selected Rainier Beach and Sammamish, two service areas with distinct differences in transit connectivity, population density, and socio-demographics. The variables used in the measurement of cost-effectiveness were (i) travelers’ generalized costs, which consisted of in-vehicle travel time, wait time, access and egress times, (ii) service provider's costs including labor, fuel/propulsion, capital, and maintenance, and (iii) external costs such as costs for crashes, noise, and congestion. Traveler costs were estimated using Metro Flex trip data and simulated travel times for alternative modes in a scenario without Metro Flex. A traffic simulation model then assessed travel times of driving alone, Transportation Network Companies (TNCs), and fixed-transit under the hypothetical scenario where Metro Flex was unavailable, comparing TIMOD costs with these alternatives.
FINDINGS
- The results pertaining to travelers’ generalized costs for a selected day showed that Metro Flex costs were 41.3 percent and 42.5 percent lower than transit bus and TNCs, respectively. It's important to note that while Metro Flex offers lower total generalized costs for travelers compared to transit buses, the service provider's operating costs were 1.6 times higher.
- The results showed that Metro Flex was estimated to reduce travelers’ generalized costs by an average of 67.7 percent compared to fixed-route bus when travelers from different income groups were considered from the two study areas.
- It should also be noted that in both study areas, driving alone tends to have the lowest social cost among the alternative modes, largely because drivers do not experience waiting times or deadhead miles.
