Comparative Analysis of Speed Limits On urban Roads Balancing Safety & Mobility

Abstract

In today's rapidly urbanizing world, cities are confronted with the dual challenge of enhancing mobility to accommodate growing vehicle populations while also prioritizing safety on urban roads. This delicate balance is directly influenced by the posted speed limits (PSLs) on roads. Typically, PSLs are determined based on the 85th percentile speeds of vehicles on roads, as well as other considerations such as road characteristics, geometric design, traffic flow, and safety measures. However, some PSLs may not effectively align with existing road design and traffic patterns, resulting in inconsistencies. These inconsistencies can disrupt traffic flow; excessively low PSLs on high-capacity roads can lead to congestion, while high PSLs on low-traffic roads might compromise safety. This study aims to understand speed limit behavior and provide recommendations for improving road safety and mobility. The research focuses on the comparative analysis of speed limits across diverse zones of urban areas to comprehend existing conditions and variations within and across cities. For comparison, four cities are selected: Agra, Lucknow, Bhopal, and Indore, which are ranked 2nd, 6th, 25th, and 28th, respectively, in accidents according to the Accident Report 2022 by MoRTH. The study is conducted on higher hierarchy roads, including arterial, sub-arterial, and ring roads of urban areas. Data is collected from both primary and secondary sources to gather valuable information, including details such as PSL value, location, direction, signage type, reason for the upcoming PSL, continuity, and mutual relatedness. Spatial factors such as distance from the city center, proximity to intersections, geometrical factors like right-of-way width, land use pattern changes, and transition zones are analyzed to understand different PSL behaviors. Additionally, this research examines how different speed limits impact travel times and delays in urban areas, along with speed distribution, aiding in the analysis of speed variations by examining existing traffic conditions and speed limits. The results indicate that PSLs are highly influenced by right-of-way and less influenced by land use, increasing as one moves outward from the city center. Through comparative analysis, this research provides evidence-based recommendations for implementing optimal speed limits or improving existing speed limit policies in urban areas. Safe transition distances have been Comparative Analysis of Speed Limits on Urban Roads: Balancing Mobility and Safety Department of Transport Planning, School of Planning and Architecture, Bhopal (MP)- 462030, iv recommended in transition zones for different PSLs based on the findings of this research. Keywords: Posted Speed Limits, Road Safety, Landuse, Right of Way, Transition Zone, Travel time, Road Geometry