Safety and operational analysis of lane widths in mid-block segments and intersection approaches in the urban environment in Nebraska.

PDFTech ReportSPR-P1(13) M327Urban areasSignalized intersectionsTraffic safetyTraffic lanesWidthApproach lanesTraffic speedHeadwaysAccident ratesRegression analysisPoisson distributionsNebraskaNebraska Transportation CenterSharma, AnujLi, WeiZhao, MoRilett, Laurence R.Iowa State University. Dept. of Civil, Construction and Environmental EngineeringNebraska. Dept. of RoadsUnited States. Federal Highway AdministrationUS Transportation CollectionThis research examined the safety and operational effects of roadway lane width on mid-block segments betweensignalized intersections as well as on signalized intersection approaches in the urban environments of Lincoln and Omaha,Nebraska. In the safety analysis, the Poisson and negative binomial regressions with fixed or random parameters wereestimated to evaluate the effects of lane width on annual crash frequencies at mid-block segments and intersectionapproaches. In the operational analysis, linear regressions were used to examine lane width effects on the vehicles\ue2\u20ac\u2122 speed atmid-block segments. The Kolmogorov-Smirnov test was applied to explore the effects of lane width on the vehicles\ue2\u20ac\u2122headways in the queue on the intersection approaches. At the mid-block segments in comparison with 11 ft and 12 ft widelanes, 10 ft lanes on the higher speed limit (40 mph and 45 mph) roadways had ambiguous impacts on safety, withimprovements in some locations and reduction in the others. Lanes 11 ft or 12 ft wide were found to be safer than 10 ftlanes on lower speed limit roadways (roadways located outside of the central business district with a 35 mph speed limit).On intersection approaches, the combination of narrowed left-turn lanes and narrowed through lanes was a safer optionbased on the evidence uncovered in this research