Assessment of How Multimodal and Geometric Improvements Reduce Road-Crash Frequency on the 18 Mazoria-Ashewa Meda Corridor

Abstract

Road traffic crashes represent a critical public health and safety concern in rapidly urbanizing regions across Ethiopia, mainly affecting vulnerable road users. This study assesses the safety impacts of proposed multimodal and geometric corridor development interventions along the high traffic 18 Mazoria-Ashewa Meda Corridor in Addis Ababa. Using a mixed-methods, historical crash data across 12 equal segments (500m length), field observations, regression modeling and stakeholder perception surveys were analyzed. The assessments revealed severe infrastructure deficiency: 83.3% of segments lacked continuous walkways and 100% lacked dedicated bike lanes and bus bays. Major junctions were strongly correlated with crash severity (r=0.688, p=0.013). multiple regression modeling confirmed major junctions as the dominant predictor of the Weighted Severity Index (B=40.214, p=0.02). Segment 11 (Kidanemihret roundabout) emerged as the primary blackspot (Crash Frequency (CF)=36, representing 31.3% of total crashes) due to steep gradient (~7%) and substandard geometry. Given the absence of post-intervention crash data and data limitation, Crash Modification Factors (CMFS) from the FHWA Clearinghouse and the Highway Safety Manual (HSM) were applied to project safety benefits. The projected interventions demonstrate expected reductions of 32% for dedicated bike lanes (CMF=0.68), 65% for continuous walkways (CMF=0.35), 44% for right-turn geometry modification (CMF=0.558), and 68% for left-turn/ U-turn geometry prohibitions (CMF=0.32). The hazardous Kidanemihret roundabout redesigned into a priority junction to eliminate heavy vehicle rollover risks on steep gradients. Statical evidence, CMF projections and stakeholder perceptions collectively indicate that the interventions will improve road safety.