TRB’s Transportation Cooperative Research Program (TCRP) Synthesis 75: Uses of Higher Capacity Buses in Transit Service explores the use of higher capacity (HC) public transit buses in trunk, express, long-distance commuter, Bus Rapid Transit, and special (e.g., sports and special events) services in North America. For purposes of this study, HC buses included articulated, double-deck, 45-ft, and other buses that have a significant increase in passenger capacity compared with conventional 40-ft buses.