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Safety and operational analysis of mid-block segment lanewidth and intersection approach lanewidth in the urban Nebraska environment

Wei Li, University of Nebraska - Lincoln

Abstract

This research examined the safety and operational effects of roadway lane width at mid-block segments between signalized intersections as well as on signalized intersection approaches in the urban environments of Lincoln and Omaha, Nebraska. In the safety analysis part of this research, the Poisson and negative binomial regressions with fixed or random parameters were estimated to evaluate the effects of lane width on annual crash frequency and Equivalent Property Damage Only (EPDO) crash frequency at mid-block segments as well as its effects on annual crash frequency and EPDO crash frequency on intersection approaches. In the operational analysis part, linear regressions and box plots were used to examine lane width effects on the vehicles’ travel speed at mid-block segments. Bar graphs were used to represent the relationship between lane width and the vehicles’ lane violation at mid-block segments. The Kolmogorov-Smirnov test was applied to explore the effects of lane width on the vehicles’ headways in the queue on the intersection approaches. ^ At the mid-block segments, it was preferable to implement 10-ft wide lanes on the higher speed limit (40 miles per hour [mph], and 45 mph) roadways in comparison with 11-ft and 12-ft wide lanes. In contrast, 11-ft and 12-ft wide lanes were recommended for use on lower speed limit roadways (roadways located in the central business district with a 25 mph speed limit and roadways located outside of the central business district with a 35 mph speed limit), based on the results from the annual crash frequency analysis and the operational analysis. However, the EPDO crash frequency analysis illustrates that 11-ft wide lanes were safer to be implemented on the roadways with a 45 mph speed limit compared to 10-ft and 12-ft wide lanes. 10-ft wide lanes were recommended for use on the other three types of the roadways in comparison with 11-ft and 12-ft wide lanes. ^ On intersection approaches, the combination of narrowed left-turn lanes and narrowed through lanes was a safer option based on all the evidence uncovered in this research.^

Subject Area

Civil engineering|Transportation

Recommended Citation

Li, Wei, "Safety and operational analysis of mid-block segment lanewidth and intersection approach lanewidth in the urban Nebraska environment" (2015). ETD collection for University of Nebraska - Lincoln. AAI3715379.
http://digitalcommons.unl.edu/dissertations/AAI3715379

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