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Trevor Haag

Academic Year: 2009-2010

Shared-lane markings in San Diego: low-cost, non-segregated alternative bicycle facilities

Area of Concentration

  • Transportation Planning

Key Terms:

active transport, traffic calming, shared-lane marking, sustainable transport, public health

Significance/Broader Impact:

How to properly ride a bicycle in an unmarked street is unclear to novice riders who prefer the strict white delineation of a bicycle lane.  Learning proper lane positioning is one of a bicyclist’s most valuable skills as it ultimately affects visibility, safety from roadside hazards, and However, segregation of bicycle facilities erodes bicyclists’ rights on the road and reinforces misinformation that bicycles do not have the same road rights as motorists.  Through the use of simple thermoplastic or painted symbols, safe lane positioning can be encouraged and promoted while expanding bicycle networks for the lowest cost.  These new symbols are new and still need to be proven in the real world, especially since their effectiveness has been studied only in large cities, none of which are similar to San Diego County.  California’s Shared lane markings were included in the state guidelines after a 2005 policy directive that considered a successful analysis in San Francisco.  The effectiveness of this directive in expanding the use of shared lane markings will be evaluated.

References

Krizek, K. J., and P. J. Johnson. “Proximity to trails and retail: effects on urban cycling and walking.” Journal of the American Planning Association. 72.1 (2006): 33-42. Print. 
“San Diego Regional Bicycle Plan: Existing Conditions Report” SANDAG. http://www.altaprojects.net/sandag/Documents_files/SANDAG_ExistingConditions_091208_small.pdf
Walter, C. Edward. “Suburban residential traffic calming.” ITE Journal (September 1995): 44. Urban Studies Abstracts
Tilahun, N. Y., D. M. Levinson, and K. J. Krizek. “Trails, lanes, or traffic: Valuing bicycle facilities with an adaptive stated preference survey.” Transportation Research Part A. 41.4 (2007): 287-301.
Mionske, Bob, Magas, Steven M., and Bernardi, Rick. 2007. Bicyling & the Law. Boulder, Colorado: VeloPress.

Links:

http://members.cox.net/ncutcdbtc/sls/index.html
http://www.sfmta.com/cms/uploadedfiles/dpt/bike/Bike_Plan/Shared%20Lane%20Marking%20Full%20Report-052404.pdf

Fall SRP Proposal Abstract

Bicycling is seen as clean, environmentally prudent transport and a solution to many urban traffic and health problems.  Subject to the same laws as vehicles, many bicyclists must travel in the same dangerous traffic and without suitable bike-specific facilities.  Research has indicated that rates of cycling are related to the proximity to suitable bicycling facilities.  Other research has been directed towards an improvement of cyclist facilities while acknowledging their inherent differences with other road traffic, avoiding a segregation of road facilities.  One such type of facility, the shared lane marking, has been seen as an alternative road marking for bicycles where separate facilities are inappropriate or unviable.  This study will utilize contemporary research in shared-lane markings and test the hypothesis that such markings will yield the same benefits as more intensive facilities such as dedicated bike lanes in San Diego.  If such benefits are observed, potential sites for deployment of such facilities in San Diego County will be studied.

Winter Senior Research Project (SRP) Abstract

Bicycling is seen as clean, environmentally prudent transport and a solution to many urban traffic and health problems.  Subject to the same laws as vehicles, many bicyclists must travel in the same dangerous traffic and without suitable bike-specific facilities.  Research has indicated that rates of cycling are related to the proximity to suitable bicycling facilities.  Other research has been directed towards an improvement of cyclist facilities while acknowledging their inherent differences with other road traffic, avoiding a segregation of road facilities.  One such type of facility, the shared lane marking, has been seen as an alternative road marking for bicycles where separate facilities are inappropriate or unviable.  This study determined that the shared lane marking has improved road safety, increasing awareness in a minority of cycling subjects but clearly influencing behavior in the majority.  These findings validate Caltrans’ policy directive for the deployment of such markings in narrow streets and suggest such rapid administrative directives are effective in improving public safety through their timeliness.

Evidence

Evidence was collected in an analytical study of the affect of the shared-lane markings already deployed in the City of Oceanside along Pacific St.  Compared with a control, its effectiveness in encouraging proper lane positioning was determined using empirical analysis.  Also, interviews were conducted to determine if the markings’ symbology is effective.

Spatial Dimension

Using publicly available data layers furnished by San Diego Associated Governments (SANDAG) and SanGIS, proximity of residences and points of destination to on-street bicycle facilities can be calculated, primarily for work-related trips.  This analysis done on a wide scale will allow the study to create a priority schedule according to proximity to the nearest on-street bicycle facility.  Analysis of traffic capacity of roads will be undertaken where the data are available to better identify key choke points in the county which likely occur on the lone roads providing access to large residential developments.

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