Strategies for Sharing Bottleneck Capacity among Buses and Cars

In urban settings where space is at a premium, bus lanes can often only be created via the conversion of existing general-use lanes. This can be politically infeasible in cities where bus flows are low, because the converted lanes would be under-utilized and thereby squander road space. The roadway bottlenecks would then as a result create even greater delays and queuing for car traffic. The present thesis explores novel ways in which buses and cars might share lanes within select bottlenecks. Details of these shared-lane strategies vary, depending upon a bottleneck's local operating conditions. In all cases, cars would be inserted into a shared lane in ways that impart few delays to the buses. These insertions would allow for the unused space between buses to be used, lessening the damage otherwise incurred by car traffic at bottlenecks. Hence, by reducing the car delay at bottlenecks it may become feasible to deploy ordinary bus-lane conversions elsewhere throughout a city's road network. The ordinary lane conversions would enable buses to bypass the car queues that still form at bottlenecks. Analytical assessments unveil the wide range of bus flows for which these strategies increase a bottleneck's car-carrying capacity, in comparison to reserving one of its lanes for buses only. Simulations of a real case study indicate that significant reductions in car delays can result while increasing bus speeds as much as ordinary conversions