Effects of Ceramic Raised Pavement Marker on Prohibiting Left Turns from Driveway: A Before and After Study

This study evaluates the impact of ceramic raised pavement markers (CRPMs) at an unsignalized intersection near downtown Auburn, Alabama, to deter left turns from an urban driveway. Increased traffic from a new apartment complex prompted the installation of these CRPMs, which are higher than common raised pavement markers, to prohibit left turns at one of the apartment exits. Video footage was analyzed for traffic patterns, volumes, and conflicts over 40 h before and after installation. The Wilcoxon signed-rank and Fisher’s exact tests assessed changes in traffic behavior and vehicle types due to the CRPMs. Findings show CRPMs effectively discouraged illegal left turns, prompting drivers to opt for right turns followed by left turns as detours. This reduced traffic from the targeted exit, suggesting some drivers use alternate routes. This research demonstrates CRPMs’ potential as a noninvasive measure to improve urban traffic flow and safety by limiting left turns from urban driveways.