An assessment of the effectiveness of traffic calming measures on road safety in Nyarugenge district, Kigali city, Rwanda

Abstract

Traffic congestion and pedestrian safety remain critical challenges in Nyarugenge District, one of Kigali's most densely trafficked areas and home to Rwanda's Central Business District (CBD). This study aims to assess the effectiveness and suitability of traffic calming measures and their impact on road safety in Nyarugenge District, Kigali City, Rwanda. The specific objectives were to: (i) identify and map existing traffic calming devices across the district; (ii) evaluate their geometric compliance with Rwanda Transport Development Agency (RTDA) standards and their influence on driver and pedestrian behavior; and (iii) formulate evidence-based guidelines for improved device installation, spacing, and maintenance. A mixed-methods approach was employed, combining field surveys using GPS and engineering measurement tools, structured traffic behavioral observations during peak and off-peak hours, and questionnaires administered to road users and transport technicians. Data was analyzed using Microsoft Excel and SPSS. Key findings revealed that 39 traffic calming devices were identified across the district, comprising 21 speed humps, 5 rumble strips, 10 warning signs, and 3 pedestrian crossings. Geometric analysis showed that 43% of speed humps exceeded the RTDA maximum height standard of 100 mm, with flat-topped humps in Nyabugogo and Kiyovu reaching heights of up to 153.5 mm. Additionally, 25% of devices showed visible degradation in marking or signage. Behavioral observations indicated higher driver compliance during peak hours (75–82.5%), with compliance declining during off-peak periods when enforcement presence was reduced, and with recurring violations including speeding near schools and failure to yield at pedestrian crossings. These findings are significant because they provide the first systematic, field-based evidence of the geometric compliance and behavioral effectiveness of traffic calming infrastructure in Nyarugenge. The implications for policy and practice are clear: responsible agencies must enforce RTDA design standards, reconstruct non-compliant humps, expand rumble strip coverage to accident-prone zones, and conduct public awareness campaigns. Without targeted intervention, the current infrastructure will continue to fall short of its road safety objectives.