Vehicular speeds on roadway segments in the District of Columbia were evaluated in 2006. Since then, various safety and traffic improvements projects were implemented in order to improve traffic flow and increase motorist compliance with speeding. This research is aimed at evaluating and comparing speeds on some of the same roadway sections that were evaluated in 2006. The project team, in collaboration with the District Department of Transportation (DDOT), chose 193 site locations throughout Washington DC at which spot speed data was collected between August and December 2010. The sites chosen were a broad subset of the 400 locations at which speed data was collected in 2006. This research examines the effectiveness of safety programs implemented between 2006 and 2010 on speed reduction. Compared with the 2006 speed statistics, the results showed that there was a reduction in the mean and 85th percentile speeds by 64% and 68%, respectively at the locations studied. Of the 193 locations, however, 51 (26%) locations recorded increases in the mean speeds while 49 (25%) locations recorded increases in the 85th percentile speeds. At 19 of the 193 locations, there were no changes in the mean speed while no changes in the 85th percentile speeds were recorded at 12 locations. Statistical significance for the changes in the mean speeds was confirmed at 5% level of significance. (Author/publisher)
Abstract