Transactions on Transport Sciences

Transactions on Transport Sciences X:X

The Impact of Low-Cost Black Spot Treatment: A Case Study of a Multi-Level Bridge in Karachi, Pakistan

Afzal Ahmed^a, Ashar Ahmed^a, Mir Shabbar Ali^b

^a. NED University of Engineering and Technology, Karachi 75270, Pakistan

^b. Sir Syed University of Engineering and Technology, Karachi 75300, Pakistan

Treatment of high accident concentration areas plays a crucial role in safety improvement. This paper presents a detailed case study on data-driven identification, analysis, improvement, and benefit-cost evaluation of a selected black spot in Karachi, Pakistan. The black spots were identified based on the accident data collected from 2007 to 2015 at the Road Traffic Injury Research & Prevention Center (RTIRPC). Road safety audits and on-spot accident investigations were conducted to investigate the contributing factors. The black spot under consideration is a bridge passing over an interchange in the southern part of the city near the coastline. The proposed interventions were implemented with the help of funding from the private sector. The pre-treatment economic loss due to road traffic injuries, fatalities, and loss of work was calculated. The post-treatment benefits in terms of reduction in accidents and corresponding injuries and fatalities were estimated using RTIRPC data, and the benefit-cost ratio was examined. The post-treatment data showed a significant reduction in all types of accidents. It was concluded that low-cost treatments such as reduction in speed limit, provision of cat eyes, road signs, and transverse markings along with strengthening of safety barriers resulted in a benefit-cost ratio of 42.5.

Keywords: Benefit-cost ratio; Black spot treatment; Horizontal curve; Injury prevention; Road traffic accidents

Received: December 16, 2023; Revised: January 14, 2025; Accepted: January 28, 2025; Prepublished online: May 6, 2025