Effect of Traffic Calming Measures on Passenger Cars in Kuala Lumpur

Speeding remains a significant contributor to road traffic crashes and fatalities worldwide. Traffic calming measures (TCMs) are widely employed to address this issue by reducing passenger car speeds and enhancing road safety. This study evaluates the impact of various TCMs, including yellow transverse bars (YTB) and raised pedestrian crossings (RPC), on passenger car speeds at four locations in Kuala Lumpur, Malaysia. Speed data were collected during off-peak hours under consistent conditions before and after implementing the measures. YTB and speed limit signs were newly introduced at three locations (Locations 1, 2 and 3), while Location 4 featured pre-existing YTB, augmented with an RPC and additional signage. Passenger car speeds were analysed using independent sample t-tests, and the magnitude of speed reduction was assessed using Cohen's D effect size. A meta-analysis of effect sizes was conducted across all locations to evaluate the pooled impact. Results revealed varying effectiveness of the interventions. At Locations 1 and 2, speed reductions were minimal and statistically insignificant, attributed to low traffic volume and urban driving conditions. However, Location 3 showed a significant reduction in mean speed due to the combined effects of YTB and downstream traffic signals. At Location 4, the introduction of an RPC significantly reduced speeds near the crossing, with a large, localised effect size. The findings highlight the importance of tailoring TCMs to site-specific traffic conditions and infrastructure. While YTB showed limited standalone effectiveness, RPC demonstrated substantial speed reductions, particularly near pedestrian crossings. Future research should explore enhancements to TCM designs, such as increasing YTB thickness, to maximise their impact on driver behaviour and road safety.