Asian Journal of Probability and Statistics

Road traffic accidents are still a huge problem for public health in Nigeria, and they cause a lot of injuries, disabilities, and deaths. This study utilized a Semi-Markov Process (SMP) model to evaluate the effectiveness of various road safety policy interventions by simulating transitions among five states: S₀ (No major national policy), transitioning with certainty to S₁ (Seatbelt law enforced in 2003), then to S₂ (plus Speed Limiter enforcement in 2017), followed by S₃ (plus Driving School Standardization Program in 2018), and ultimately to S₄ (plus FRSC Mobile App and NACRIS introduced in 2024). The transition probabilities and mean waiting times for each state were derived from actual data. The study found that the average stay period was 7.2 years, which was what the SMP model said it would be (7.19 years). The estimated first passage time to mortality reduction (S₄) was highest from the baseline state S₀ (15.9 units) and went down steadily across S₁ (13.3 units), S₂ (7.9 units), and S₃ (6.9 units). This illustrates that modifying how we enforce speed limits makes it easier to meet our goals of lowering deaths. There was also a five-year forecast for road traffic mortality between 2025 and 2029. This demonstrated that the number of deaths might alter, and if no new policy is put in place, it could be anywhere from 5,296 to 5,547. These results support the idea that legislation should be the most important part of road safety programs, especially when it comes to speed limits and strict enforcement. The Semi-Markov framework has been beneficial for simulating the dynamics of road safety and can assist policymakers to make decisions that will minimize the number of deaths caused by road traffic crashes. Over time, improving Nigeria’s road safety measures in various ways can have a huge effect on the country’s traffic challenges.