Assessing and optimizing signalized and unsignalized intersection efficiency and safety through integrated comparative analysis in Debre Markos town, Ethiopia

This study proposes an integrated analytical and statistical framework to diagnose and optimize the linked challenges of operational efficiency and safety at urban intersections in Debre Markos Town. Moving beyond conventional analysis, the research introduces a critical distinction: performance at signalized intersections is a matter of "Managed Risk," while at unsignalized intersections, it is one of "Negotiated Risk," with each type governed by fundamentally different mechanisms. The key findings show that for signalized intersections, delay is an engineering problem controlled by saturation headway and cycle time, whereas safety is an exposure problem driven mainly by vehicle speed and pedestrian volume-highlighting a clear decoupling between efficiency and safety. In contrast, at unsignalized intersections, congestion is the dominant factor; both efficiency and safety break down together under saturation, with vehicle speed having a major impact on delay and crash frequency. Synthesizing these insights, the study provides a robust, evidence-based framework for optimization. For signalized intersections, tailored strategies include signal retiming, dedicated pedestrian phases, and targeted speed calming. For unsignalized intersections, the primary levers are congestion management through geometric improvements or roundabout conversion, assertive traffic calming, and control of minor-road traffic inflow. A clear decision protocol is also offered for converting unsignalized intersections based on saturation and delay thresholds. The conclusions affirm that a universal approach is ineffective. Sustainable urban mobility requires dual strategies: precision engineering for signalized intersections and systemic exposure management for unsignalized ones, all supported by integrated pedestrian safety and town-wide speed control. This research provides a practical, transferable blueprint for data-driven traffic management that enhances both mobility and public safety in developing urban settings.