A design methodology for both comfortable and accessible passenger rooms for public transport has been developed based on observation and modeling of seat-taking behaviors. The developed model consists of variables of visual environment of passenger rooms, whose parameters are identified through full-scale mockup experiments. The model enables quantitative comparisons between design alternatives of seat arrangements and door usages, thus this has been applied to propose seat arrangements for railway vehicles, light rail vehicles and a new unmanned energy-saving small urban transport system called “Eco-Ride” with small additional procedures for model extension.