Evaluating Interior and Door Configurations of Rail Vehicles by Using Variable Loading Densities


Samuel W. Lau

Document Type

Journal Article

Publication Date


Subject Area

operations - capacity, infrastructure - vehicle, mode - rail, mode - subway/metro


Vehicle capacity, Variable loading densities, Subway cars, San Francisco Bay Area Rapid Transit District, Rapid transit cars, Rapid transit, Rail transit, Interior design, Heavy rail transit, Dwell time, Doors (Vehicles)


As many U.S. metropolitan areas expect unprecedented growth in population and travel in the next 20 to 30 years, rail transit agencies are faced with the challenges of replacing their aging fleets and procuring new vehicles to keep up with ridership increases. As funds become increasingly scarce, many operators are exploring ways of increasing car capacity by considering interior configurations (to maximize loading efficiency) and door configurations (to minimize the effect of increased loads on station dwell times). Few studies address the design and evaluation of interior and door configurations as a system. Typically, seating configurations are designed separately from door configurations. Furthermore, interior configuration evaluations or maximum vehicle loading quoted by car manufacturers assume a uniform loading density applied throughout the car. Loading on transit vehicles, however, varies greatly within a car. This affects practical vehicle capacity and its impact controlling dwell time at the busiest door. The San Francisco Bay Area Rapid Transit District, a heavy rail rapid transit system in California, recently conducted an evaluation of interior and door configurations based on a methodology that used variable loading densities and resulting impact on door loads for dwell time estimation. Variable loading density is more realistic in simulating actual passenger loading experience. This research shows that depending on the interior and door configuration, applying uniform loading density may misrepresent actual car capacity and door loads and thus waste valuable resources or underestimate actual needs.