Purpose Road accident is a major threat to sustainable road safety, causing immense suffering and posing an increasingly serious global challenge, especially in developing countries. It is the leading cause of death, injuries and property damage. While vehicle driver-related factors play a significant role in accidents, poorly designed and constructed roads are also a growing factor. As result, this study aims to assess traffic accident problems associated with design-construction complications on Arba Minch-Jinka Road, Ethiopia. Design/methodology/approach From 2013 to 2021, a large amount of traffic accident data was gathered, and through actual roadway surveys at potential locations along the road, the data was associated with design-construction parameters. The analysis was done by adopting descriptive statistics incorporating comparative hypotheses, in which the individual and combined effects of design-construction issues were identified. Results revealed, on average, 76% of total coincided accidents along the study road were associated with design-construction issues. Exclusively, causing factors, i.e. roadway, driver, vehicle, pedestrian problems and environmental, contributed 7.65%, 77.78%, 6.17%, 6.05% and 2.35% traffic accidents, respectively. Findings Detailed and time-consuming data collection, investigations, analysis and assessments were used in the research to discover a strong association between road design-construction problems and traffic accidents. As a result, 42 black spot sections were identified, and 7.65% is exclusively caused from design-construction problems. Curved road sections led the surge by 42% from selected design-construction variable, whereas the remaining 58% was shared among four parameters. According to relative analysis, design-construction issues caused a 58.17%, 12.14%, 32.36% and 29.93% increase in accidents in combination with driver, vehicle, pedestrian and environmental factors, respectively. This is in an average of 33.15% escalated problem in a combination that raises questions about the sustainability of road safety. Originality/value It is essential to use scientific methodologies to evaluate traffic accidents and associated design-build discrepancies in developing nations like Ethiopia if we are to achieve sustainable road safety. The fundamental importance and value of this study is that it promotes accountability to the road design and construction, which are not frequently thought of as influencing factors in traffic accidents. This paper is original, and all references have been correctly mentioned, to the best of the author’s knowledge.