Unsafe driver behaviour is regarded as the most significant contributory factor in road traffic crashes in Nigeria, and the prevailing road safety culture in the country is one aspect which sustains the high crash rate. This research used a problem-oriented approach with the intention to recommend research-based solutions to road safety problems in Nigeria while considering cultural and environmental factors that provoke different driving styles and behaviours. It aims to identify which, among culture and road environment, has a stronger influence on drivers' behaviour and how behavioural changes can be achieved. To achieve this, a multi-method approach was adopted in different phases. Phase 1, an exploratory study involved on-road observation of traffic behaviour and conflicts in Nigeria using the Traffic Conflict Technique (TCT). It provided an understanding of the general traffic behaviour of various road users, showed the effect of various factors on conflict severity and helped to identify the most prevalent unsafe behaviours found in this environment. Based on the results of this study, a driving simulator experiment was designed and carried out in Phase 2, comparing the driving style of three groups of drivers in varying road conditions. These were Nigerians with no experience of driving in the United Kingdom (UK), Nigerians with some experience of driving in the UK and UK drivers. The conditions varied depending on how much regulation was provided (low or high infrastructure). A short road safety awareness-raising intervention for Nigerian drivers with no experience of driving in the UK was also evaluated. It was hypothesised that those Nigerian drivers with no experience of driving in a highly regulated UK road system would not be encouraged to adopt a safe driving style. This would have implications for the use of road safety interventions in Nigeria that have been developed outside the Nigerian context. In addition, participants completed the Driving Behaviour Questionnaire (DBQ) to compare reported behaviour and objectively measured driving behaviour in various traffic scenarios (overtaking, lane changing, car following etc.). Since many road safety measures could not evaluated for Nigerian drivers in phase 2, a focus group study was conducted in Phase 3 with the lead road safety agency in Nigeria-the Federal Road Safety Corps (FRSC). The study investigated the perceived effectiveness and ease of implementation of a wide range of road safety measures on drivers' behaviour including those that were evaluated in Phase 2 (simple engineering measures and awareness-raising campaigns). Results provided a greater understanding of the road safety situation in Nigeria. Some of the unsafe behaviours identified in Phase 1 are distinct and can only be found in a particular cultural environment like Nigeria because of the traffic conditions and vehicle fleet. Investigating some of these behaviours in Phase 2 and comparing them with the behaviour of drivers from other cultures showed that there were distinct differences in behaviour between all the groups in most of the traffic scenarios. Nigerian drivers with no experience of driving in the UK were more likely to engage in unsafe driving behaviours compared to other groups. Improvements in the road environment did not bring about any significant changes in the behaviour of this group of drivers. However, small changes were observed after the awareness-raising intervention. The results indicate that the behaviour of drivers are interpretable in relation to their traffic safety culture, and are only partly influenced by their driving environment. Specifically, drivers' traffic safety culture has a greater influence on their behaviour compared to changes in the road environment. Findings from the focus group study in phase 3 revealed that road safety measures such as education and information campaigns are perceived to have the potential to be very effective and easy to implement in Nigeria compared to other measures. The research findings provide an innovative approach to defining the key safety-critical behaviours which are prevalent in Nigeria as well as starting to understand how features of the road environment and/or training could be used to improve the road safety record in Nigeria. It also has implications for the design of road safety interventions in developing countries, particularly with respect to the non-portability of infrastructure measures from developing countries.