Bicycling as a mode of travel in Santa Clara County and the Silicon Valley is currently a small fraction of the overall travel market, comprising only 1.7 % of all commuter trips (1). However, the region has made a strong commitment to increasing the share of trips made by bicycle by designating over $300 million in committed funds for bicycle infrastructure improvements in the adopted long-range Valley Transportation Plan (VTP) 2040. The Valley Transportation Authority (VTA) is the agency responsible for developing and maintaining the Countywide models to support multimodal project planning and congestion management. While bicycle mode choice estimation capabilities were a part of the previous model structure, the methods were very coarse and not sensitive to changes in bicycle infrastructure.
The VTA recently developed a straightforward method for improving the representation of bicycle trips in the Countywide models through the addition of bicycle network detail, enhanced bicycle travel time estimation and performing a comprehensive validation of estimated bicycle volumes to observed bicycle count data. Some specific features of the modeling approach include:
• Explicit coding of bicycle infrastructure in the model networks, including bike lanes and paths,
• Collection of bicycle speeds data using a smartphone application,
• Processing of smartphone application data outputs using GIS to develop a bicycle speed cross-classification scheme based on area type and facility type,
• Development of impedance matrices for bicycle trips from the coded networks and incorporating the results in the mode choice models,
• Performing bicycle trip assignments,
• Performing a comprehensive validation of the modeled volumes to observed counts,
• Application of model forecasts to test and quantify model responses and impacts on bicycle mode shares.
After the model was validated to observed bicycle count data, a series of selective bicycle corridor improvements was implemented to test the ability of the models to provide meaningful results for bicycle planning applications, including development of evaluation measures. As this project represented a proof-of-concept application, a series of enhancements was also defined and are currently being implemented in a comprehensive update of the Countywide models.
(1) ACS 2012 5-Year Estimates