Conversions of Wide Curb Lanes

Abstract

This paper examines the operational effects of converting a 14-ft-wide curb lane to an 11-ft-wide travel lane with a 3-ft-wide undesignated lane at various locations in Broward County, Florida. Six midblock sites with various configurations were selected for study. Two of the midblock sites had previously been striped with the 3-ft undesignated lane, and these served as comparison sites. Videotapes were taken of bicyclists riding through the midblock and intersection locations before and after placement of the 3-ft undesignated lane striping. At the locations where the 3-ft stripe was already in place, the videotaping was done to examine whether changes were occurring over time. Software was used to extract images at all midblock locations so that before and after lateral spacing measurements could be obtained. After the new striping, ( a) bicycles were ridden, on average, 7 to 9 in. further away from the gutter pan seam; ( b) motor vehicles were driven, on average, 6 to 12 in. farther away from the gutter pan seam; ( c) passing motor vehicles were driven, on average, 3 to 5 in. closer to bicycles at curb and gutter sites; conversely, passing motor vehicles were driven, on average, 4 to 5 in. farther away from bicycles at the sites where the stripe was already in place; and ( d) the addition of the stripe at new locations had the effect of reducing the amount of motor vehicle encroachment into the adjacent lane on these multilane roadways.