Bridging the Gaps: How Quality and Quantity of a Connected Bikeway Network Correlates with Increasing Bicycle Use

• Authored by:  M. Birk , R. Geller

Birk, M. and R. Geller, “Bridging the Gaps: How Quality and Quantity of a Connected Bikeway Network Correlates with Increasing Bicycle Use,” Presented at the Transportation Research Board 85th Annual Meeting (2006)
This study documents how a series of design improvements and efforts to complete gaps in Portland, Oregon’s bicycle networks, particularly at bridges into downtown, have resulted in significant increases in bicycle traffic at these locations. The authors note that:“Annual bicycle counts on Portland’s central city bridges, which connect close-in residential neighborhoods across the Willamette River to the city’s primary commercial and employment center, show a 210% increase in bicycle trips between 1991 and 2004.” Strategies focused on safety enhancements at conflict areas (e.g., clearly marked transitions between bicycle lanes and off-street paths, closure of on-ramp, reconstruction of conflict areas on approaches, blue bike lane implementation in conflict zones, separation on bridge spans versus bike lanes or shared lanes). Costs were contained by coupling improvements with other bridge upgrade or reconstruction projects where possible. See also “Blue Bike Lanes for Cycling Safety” (City of Portland, 1997).
Boulevard arterial crossings are designed for each situation, and include bicycle-only signals where needed, adjustments to timing on other signals, and installation of bicycle boxes at one intersection to assign priority to cyclists. Traffic calming techniques are used on selected high speed boulevards and blue bicycle lanes assign priority to bicyclists in an area of an auto-bicycle weaving. Bridges showing the highest concentration of bicyclists are those where crossings are off-street on wide sidewalks or a shared use path, with bike lanes on the approaches These improvements, combined with