Evaluation of Bike Boxes at Signalized Intersection

Principal Investigator: Jennifer Dill, Ph.D.
Co-principal Investigator: Christopher Monsere
Graduate Research Assistant: Nathan McNeil, MURP

Start Year: 2008

Estimated Complete Year: 2009

Sponsor: OTREC, City of Portland, PSU (Civil & Engineering and Urban Studies & Planning)

Budget: $72,133

Abstract: Bicycle use as a primary means of commuting to work increased 145% (American Community Survey, US Census Bureau) from 1996 to 2006 in Portland, Oregon; however, recent surveys have found that more than half of Portland residents limit their bicycling due to traffic safety concerns. In Portland, 68% of bicycle crashes occur at intersections, (PDOT, 2004) which is consistent with national trends (Hunter et al., 1996), and a common crash pattern is the "right-hook" where right-turning motorists collide with through or stopped bicycles.

To partially address these conflicts between bicycles and right-turning motor vehicles, the City of Portland installed 12 "bike boxes" at signalized urban intersections. The box is located in front of the stop line for motor vehicles and behind the pedestrian crosswalk, and the typical installation consisted of an advanced stop line, green textured thermoplastic marking with bicycle stencil, intersection striping, and regulatory signage (including no-turn-on-red). These installations also include colored bicycle lane markings in the intersection, which is unique. This combination of traffic control is hypothesized to reduce conflicts between motor vehicles and bicyclists and make motorists aware of a potential conflict, with a secondary outcome of encouraging more bicycling by enhancing safety and priority at an intersection.

Bike boxes and similar advanced stop lines are used extensively in the United Kingdom, the Netherlands, Denmark, and other European countries. However, bike boxes are rare in the United States and extremely limited research has been conducted on their effectiveness. We are conducting a comprehensive, classical, observational before-after study of the effectiveness of the installed experimental traffic control devices and responses of all system users impacted by the installation of the bicycle boxes.

Our approach will answer such research questions as:

• Do the bike boxes reduce conflicts or the potential for conflict between motorized vehicles and bicycles?
• Do the bike boxes create any new or potential conflicts between motorized vehicles and bicycles?
• How does motor vehicle driver and bicyclist behavior differ with and without the bike boxes?
• What design features affect behavior and conflicts?
• Do the bike boxes affect pedestrian safety, behavior, or conflicts with motor vehicles or bicyclists?
• What are the impressions of the drivers and bicyclists using the intersections about how the bike boxes affect safety and operations?

Two primary research methods will be employed: (1) before and after video surveillance of the intersections where bike boxes will be installed and appropriate control intersections; and (2) surveys of cyclists and drivers. The video surveillance will address most of the research questions in an objective manner.