Safety Evaluation of Selected Intersections Using Historical Crash Data and Surrogate Traffic Conflict Measures - the Case of Yeka Sub City Addis Ababa

Abstract

Urban intersections are critical locations in road network where vehicular traffic and pedestrians interact. It results in substandard safety performance due to geometric deficiencies. Traditional safety evaluations depend on historical records solely which suffers systematic under reporting and provide are active frame work. This study used a reactive proactive approach by integrating historical crash data analysis with microscopic traffic simulations and surrogate safety measures (SSMs) to evaluate five high risk intersections in Yeka sub city Addis Ababa. Kotebe K/mihret, kotebe Zero hulet, Kotebe College, Abem and Kara junctions. Intersections were screened and prioritized using the equivalent property damage only (EPDO) scoring method. A microscopic simulation was developed using SUMO and trajectories were analyzed using the surrogate safety assessment model (SSAM) to capture time to collision (TTC) and post encroachment time (PET). Based on identified deficiencies engineering interventions are proposed following AACRA, ERA and AASHTO design standards. The post redesign SSAM evaluation revealed a 36.9% overall reduction in total traffic conflicts. This confirmed that integrating historical crashes with proactive surrogate measures creates a more robust framework for urban traffic safety management. This study concluded that for evaluating urban intersection safety, integrating historical crash analysis with surrogate conflict measures provide more comprehensive and reliable frame work than relying on historical crash records solely.