Review on Assessing Urban Traffic Crash Risk and its Impact on Mode Choice using Safety Performance Functions

As cities rapidly expand and traffic congestion intensifies, urban road safety has emerged as a major concern. Vulnerable road users such as pedestrians, cyclists, two-wheeler riders, and car passengers face different levels of crash risk. This paper reviews research on the use of Safety Performance Functions (SPFs) to quantify urban traffic crash risks. These statistical models describe the relationship between crash frequency and factors such as population, traffic density, and road characteristics. By analyzing historical crash data and road geometry, researchers can estimate crash likelihoods at intersections, mid-blocks, and roundabouts. High-risk zones are often those with heavy traffic and inadequate pedestrian infrastructure. Similarly, poor visibility and high-speed traffic contribute to increased crash severity. The review highlights the importance of reducing vehicle speed, improving street lighting, and providing pedestrian-friendly infrastructure to enhance urban road safety.