The main objective of this project was to examine the operational effects of converting 14-ft wide curb lanes (WCLs) to an 11-ft travel lane with a 3-ft undesignated lane at various locations in Broward County, Florida. Six midblock and four intersection sites were selected for study. The selected study sites were a mix of configurations to provide comparisons. One of the midblock sites where the stripe was newly added did not have curb and gutter. Two of the midblock sites had been previously striped with the 3-ft undesignated lane. The study design was before-after in which data were collected prior to and after the stripe designating the 3-ft lane was deployed. The ideal would have been before-after with comparison sites, but obtaining matching comparison sites would have been very difficult. Videotapes were taken of bicyclists riding through the midblock and intersection locations before and after placement of the 3-ft undesignated lane striping. In the locations where the 3-ft stripe was already in place, the videotaping was done to examine whether changes were occurring over time. To an extent, these previously-striped roadways served as control or comparison sites. Once the videotaping was complete, software was used to extract images at all midblock locations so that before-after lateral spacing measurements could be obtained. After the new striping: (1) bicycles were ridden, on average, 7 to 9 in. farther away from the gutter pan seam; (2) motor vehicles were driven, on average, 6 to 12 in. farther away from the gutter pan seam; (3) 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 6 in. farther away from bicycles at the sites where the stripe was already in place; and (4) 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 multi-lane roadways.
Abstract