Feasibility of One-Dedicated-Lane Bus Rapid Transit/Light-Rail Systems and their Expansion to Two-Dedicated-Lane Systems: A Focus on Geometric Configuration and Performance Planning

摘要

This report consists primarily of two parts, the first on feasibility and the next on space minimization. In the section on feasibility, we propose the concept of a Bus Rapid Transit (BRT) or light-rail system that effectively requires only one dedicated but reversible lane throughout the system to support two-way traffic in the median of a busy commute corridor with regular provision of left-turn lanes. Based on key ideas proposed in that section, the section on space minimization first addresses how to implement a two-dedicated-lane BRT or light-rail system with minimum right-of-way width and then proposes ways to expand a one-dedicated-lane system to two dedicated lanes. In a one-dedicated-lane system, traffic crossing is accommodated on the otherwise unused or underused median space resulting from provision of the left-turn lanes. Although not necessary, some left-turn lanes can be sacrificed for bus stops. Conceptual design options and geometric configuration sketches for the bus stop and crossing space are provided in the section on feasibility, which also discusses system performance in terms of travel speed, headway of operations, distance between two neighboring crossing spaces, and number of crossing spaces. To ensure practicality, we study implementation of such a system on an existing corridor. Such a system is also useful as an intermediate step toward a two-dedicated-lane system because of its potential for facilitating transit-oriented development. In typical existing or planned BRT or light-rail systems implemented with two dedicated traffic lanes, a space equivalent to four traffic lanes is dedicated for a bus stop. In the section on space minimization, we propose implementations requiring only three lanes at a bus stop, based on two key ideas proposed for a one-dedicated-lane system. That section also discusses ways to expand a one-dedicated-lane system to its corresponding two-dedicated-lane system.