Developing an effective speed limit compliance intervention for Nigerian drivers : a study of drivers who work in a fleet company with strong safety culture

Travelling at illegal and/or inappropriate speed continues to be the single biggest factor in road traffic crashes and fatalities in Nigeria. Existing evidence suggests that drivers, particularly those who work in companies with a strong safety culture exhibit different sets of speeding attitudes and behaviours in work and private driving. This research is based on the premise stated above, and the lack of speed-related research in Nigeria. Using Ajzen’s Theory of Planned Behaviour (TPB: Ajzen, 1991), this thesis investigates the socio-cognitive determinants of speeding behaviour of drivers’ in their work and personal vehicles. It also sought to test and evaluate the efficacy of two speed limit compliance interventions on driver behaviour and safety. Using a multi-method approach, four independent but related studies were carried out. Study 1, a qualitative study hinged on the TPB, elicited the salient beliefs drivers’ held towards speeding. Study 2, a quantitative study inspired by the TPB was used to investigate differences in drivers’ attitudes, and self-reported behaviour in their work and private vehicles. It also measured the effects of the interventions on the TPB constructs. Study 3, an experimental study, tested the efficacy of a smartphone-based advisory Intelligent Speed Assistance (ISA) application, and TPB-based Speed Awareness Course (SAC) on drivers’ speed choice. Study 4, a prospective survey, examines the acceptability of ISA using the Unified Theory of Acceptance and Use of Technology (UTAUT: Venkatesh et al., 2003). The results provided greater understanding into a range of salient beliefs influencing the speeding behaviour of Nigerian drivers which are peculiar to the socio-cultural context. The findings show the TPB model explained up to 24% of the variance in Intention to comply with speed limits. As predicted, participants reported a higher Intention to comply with speed limits in their work than private vehicle. Drivers’ attitude emerged as the most significant predictor and strongest correlate with Intentions to comply with the speed limit in both work and private vehicle. The TPB was also applied to evaluate changes in drivers’ speeding cognition following experience with the ISA and the speed awareness course. There was no evidence of any substantial changes to any of the TPB constructs following short-term experience with the ISA, and speed awareness course. Also, investigation of the relationship between TPB variables and observed speeding behaviour suggests that higher levels of drivers’ Intentions toward speed limit compliance and Strong Perceived Behavioural Control are correlated with lower levels of objectively measured speeding behaviour. Further, the dichotomous groups of low Intenders and high Intenders had significant differences in their observed speed, with the former more likely to engage in speed limit violations. Findings from the ISA and SAC intervention with regards to speed choice and safety revealed significant reductions in speed violation, reduced mean speeds, and speed variability. The findings have important theoretical and applied implications for the development of better speed limit compliance interventions to improve driving behaviour, and general road safety.