A Comparison of Daytime and Nighttime Operating Speed on Rural Multi- Lane Highway Sections in Egypt

Traditionally, the 85th percentile of observed speeds is used to represent operating speed associated with a specific site certain geometric features. The presence sunlight enhances vision drivers during daytime while visibility usually degrades nighttime, especially on rural roads where no street lighting exists, and would depend solely their vehicle headlights. Visibility degradation safety concern which magnified horizontal curves. objective this study, therefore, compare in nighttime conditions both tangent sections analysis made use spot data collected curves two major multilane highway Egypt. Spot were using guns nighttime. calculate mean speed, variance speed. Analysis Variance (ANOVA) was For most cases, it shown that significant difference existed for This mainly attributed generous design features elements (e.g., large radii curves, wide lanes, etc.). An attempt develop models see variables impact daytime. results models’ development deemed inappropriate due lack variability speeds.