Getting more from our roads: an evaluation of special vehicle lanes on urban arterials

With increasing demand for travel and limited opportunities for increasing capacity within urban areas there is increasing pressure to make more effective use of the capacity available. One approach is the introduction of special vehicle lanes where particular classes of traffic, typically buses and high occupancy vehicles are permitted to use the lane. Vehicles eligible to use special vehicle lanes typically represent only a limited part of the total traffic flow, resulting in lower and more reliable travel times for those vehicles. However, where existing road space is reallocated, other traffic may face increased congestion as the capacity available for this is reduced. Users may respond by changing their behaviour to take advantage of improved travel conditions in the special vehicle lane. Because the setup costs of special vehicle lanes are typically small, their economic assessment therefore depends critically on whether the reduction in costs for the managed traffic is greater than any increase for the remaining traffic. This report considers evidence on these issues using New Zealand data and international research and outlines a systematic approach and analytical modelling techniques for the assessment of special vehicle lanes on arterial roads.