Thursday, February 21, 2013

Green Wave for Bicycles: Findings from a Case Study in Portland, Oregon

Abstract for a new paper we're working on with Portland State University...
Over the past decade, there has been a significant increase in the proportion of active modes of transportation especially in urban areas. The benefits of these active transportation modes are well recognized: lower congestion and emission levels and advances in personal health. While there have been infrastructure improvements to cater to the growing demands of non-motorized transportation, efforts to optimize system operations for bicyclists and pedestrians have been lagging. The purpose of signal timing at intersections is to move traffic in a safe and efficient manner consistent with the policies of the local jurisdiction. In many communities, signal timing and coordination accord priority to automobile movements while other users of the transportation system are often ignored. With the goal of moving toward a 25% cycling mode split by 2030, the City of Portland has chosen to optimize signal timing operation to prioritize the needs of people on bicycle on select corridors.

This paper reports on the development of a signal timing plan for a busy bicycle commuter corridor in Portland, Oregon. The objective of the signal timing design was to provide a green wave for people on bicycles. Setting traffic signal timing to progress bicycle traffic can minimize stops, lead to platooning of bicycles, and potentially attract cyclists to the facility resulting in the safety in numbers phenomenon. The North Vancouver and North Williams corridor one way couplet in Portland, Oregon is a heavily traveled bicycle commuter route with over 3,000 bicyclists per day. In order to develop signal timing for the 13 signals on the couplet, bicycle and auto travel times and speeds were collected using GPS devices. The traffic signal timing optimization software Synchro was used to generate signal timing that allowed separate bicycle and auto coordinated progression. Post implementation, travel time and speed data was collected
to evaluate the new signal timing. Preliminary analysis indicates an average decrease of 36% in vehicle stops and 41% in bicycle stops per progressed platoon on the couplet.  The poster will report on our findings and lessons learned.

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