Evaluation of Shared Lane Markings in Cambridge,Massachusetts

Abstract

Shared lane markings (sharrows) convey the message that motorists and cyclists must share the travel way on which they are operating. The purpose of the markings is to create improved conditions for bicycling by clarifying where cyclists are expected to ride and reminding motorists to expect cyclists on the road. A before–after evaluation was conducted to compare how cyclists and motorists operated on a street with parallel parking in Cambridge, Massachusetts, with no markings versus with sharrows placed 10 ft (3.05 m) from the curb. This evaluation, which was part of a broader FHWA study on sharrows, was intended to help determine whether an alternative to the 11-ft (3.4-m) spacing recommended in the 2009 version of the Manual on Uniform Traffic Control Devices would be effective. Operational and safety measures for bicyclists and motorists were examined. Overall, safety effects appeared to be associated with the installation of the sharrows placed 10 ft (3.05 m) from the curb. Perhaps the most important effect was the 14-in. (36-cm) increase in spacing between motor vehicles in the travel lane and parked motor vehicles when no bicycles were present. This effect increased the operating space for bicyclists. Many variables related to the interaction of bicycles and motor vehicles also showed positive operational and safety effects.

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References

FHWA. Manual on Uniform Traffic Control Devices. U.S. Department of Transportation, 2009.

Alta Planning + Design. San Francisco's Shared Lane Pavement Markings: Improving Bicycle Safety. San Francisco Department of Parking and Traffic, Calif., 2004.

Pein

W. E.

, Hunter

W. W.

, and Stewart

J. R.

Evaluation of the Shared-Use Arrow. Florida Department of Transportation, Tallahassee, 1999.

California Manual on Uniform Traffic Control Devices. California Department of Transportation, Sacramento, 2003.

Harkey

D. L.

, and Stewart

J. R.

Evaluation of Shared-Use Facilities for Bicycles and Motor Vehicles. In Transportation Research Record 1578, TRB, National Research Council, Washington, D.C., 1997, pp. 111–118.

McHenry

S. R.

, and Wallace

M. J.

Evaluation of Wide Curb Lanes as Shared Lane Bicycle Facilities. Maryland State Highway Administration, Baltimore, 1985.

Hunter

W. W.

, Feaganes

J. R.

, and Srinivasan

Conversions of Wide Curb Lanes: The Effect on Bicycle and Motor Vehicle Interactions. In Transportation Research Record: Journal of the Transportation Research Board, No. 1939, Transportation Research Board of the National Academies, Washington, D.C., 2005, pp. 37–44.

van Houten

, and Seiderman

How Pavement Markings Influence Bicycle and Motor Vehicle Positioning: Case Study in Cambridge, Massachusetts. In Transportation Research Record: Journal of the Transportation Research Board, No. 1939, Transportation Research Board of the National Academies, Washington, D.C., 2005, pp. 3–14.