Impact of Lane Width on Vehicle Speed of Urban Arterials

In this paper, the relationship between free-flow speed on urban road segments and lane width is analyzed using 2006 data that was collected by video camera and image identification software. Over 9,000 spot vehicle speed data, collected at 9 road segments with similar facilities and traffic conditions but different lane widths in the urban area of Hangzhou, were used to estimate the impact of lane width on vehicle speed. Mean speed and 85th percentile speed increase as the lane widths increase. But the impact on speed variance and adjacent speed difference are different between the mid-block points and near intersection exit points. The lane width near intersection exits does not have an obvious impact on variance, but it has a quadratic impact on adjacent speed difference. However, at the mid-block, both variance of speed and adjacent speed difference increases as the lane width increases.