Modelling the effects of fuel price changes on road traffic collisions : evidence from the UK and the EU

Around 1.35 million people lose their lives in road traffic collisions around the globe each year, and millions more are affected by life-changing injuries. There are, however, signs that progress is being made in some parts of the world towards reducing these impacts. For example, there was a significant fall of around 21% in road traffic fatalities across the EU region over the decade from 2010 to 2018. Several explanations have been offered as to why this fall of deaths has occurred. These include the role of improved vehicle and highway design, better law enforcement and the impact of the economic downturn. One possible additional influence is the role of changing fuel prices, whereby rising petrol and diesel costs have coincided with reductions in traffic collisions and vice versa. Thus, fuel prices are much higher in some European countries when compared to other parts of the world, such as the USA. Increasing fuel prices is often a policy choice made to help influence car driver behaviour and reduce car use and hence limit related externalities such as road congestion, air and noise pollution. Moreover, in the UK for example, high fuel prices are a significant source of tax revenue for the Government, part of which is spent on paying towards road safety improvement projects. Recently, Governments across Europe have proposed banning sale of new petrol and diesel vehicles by 2035 as a means of meeting climate change goals and mitigating poor air quality. Given the implications such a policy would have on fuel prices, understanding the relationship between changing fuel prices and road traffic collision rates is now more important than ever. Accordingly, this thesis aims to investigate the effects of fuel price on road collision frequency. In addressing this, the thesis first draws on UK data and secondly on EU data. The UK investigation used weekly time series data of fuel prices and road traffic collisions along with other control variables from 2005 to 2015. Different types of count data modelling approaches were investigated (Poisson, Negative Binomial, Prais-Winsten and time series ARIMA/SARIMA models), and the Prais-Winsten and time series models were selected as the best models for presenting and comparing results. The model estimation results suggest that fuel prices are negatively associated with the frequency of fatal and serious collisions in the UK. It also concludes that higher fuel prices have an overall positive impact on UK road safety. For the European study, panel data from 28 EU member states collected from 2005 and 2018 was analysed. Several panel data modelling approaches (Poisson/negative binomial fixed and random effect models, generalized estimating equations (GEE)) were explored. Based on the available panel count data properties, random effect negative binomial models (RENB) and generalized estimating equation (GEE) were selected. The findings from the EU analysis largely support the UK results, confirming a clear negative relationship between fuel price and road traffic collisions across the 28 EU member states. Fuel price changes can have an impact on driver behaviour through several causal links, primarily due to changes in traffic exposure on all driver groups. This thesis findings further reinforce the previous findings related to fuel price and road traffic collisions in the high fuel prices regions, the UK and the EU. The thesis contributes to knowledge in terms of the relationship between fuel price and road traffic collisions indicating the positive role of higher fuel prices on road traffic safety in Europe. Furthermore, this thesis can help policy makers around the globe to understand the negative impact of reducing fuel prices on road traffic collisions, especially when road fossil fuel (petrol and diesel) vehicles are being phased out. Thus, the thesis emphasises the importance of higher fuel prices in the short run while in the long run charging for alternative fuel vehicles (that are currently subsidised) and introducing new road pricing policies at appropriate levels to improve and maintain road safety around the globe.