Despite the Malawi’s Mzuzu-Nkhatabay M05 road having been rehabilitated between 2013 and
2015, post rehabilitation accident reports increased, a phenomenon contrary to the popular
expectation. It was against this background that this study aimed to assess the road safety effects
of combining horizontal and vertical curves on drivers’ perception errors. Specifically, the study
focused on three elements namely; the road, vehicle, and the driver, which constitute the road
system. To achieve the goal of the study, GIS-based spatial data analysis in QGIS version 3.4, 3D
Modelling analysis in AutoCAD Civil 3D, and Analysis of Variance and T-tests in SPSS version 22
were performed on both primary and secondary data collected. The pre and post rehabilitation
data analysis results showed that, while the rehabilitation successfully corrected many road
engineering conditions, including the flattening of sharp curves to meet engineering standards,
accident rate post rehabilitation increased by 15%. Moreover, 60% of these accidents occurred at
specific bending points where road signs were missing or insufficient. Additionally, 40% of
vehicles inspected were found to be unfit due to poor maintenance, and 35% of drivers exhibited
risky driving behaviors. Therefore, the study concluded that the drivers’ behavior, the condition
of vehicles, and the inadequacy of road signage, particularly in areas with complex alignment,
contribute to the increased accident rates. Consequently, it recommends the need for improved
driver education, regular vehicle inspections, and enhanced road signage to ensure the intended
safety benefits of the road rehabilitation are realized.
Keywords: Combined road alignment, Perception error, Curvature assessment, Driver behavior, hazardous curve warning signs