Cost benefit analysis of reducing speed limits in Athens to 30 Km/h

The objective of this research is to investigate public acceptance and socio-economic feasibility of reducing speed limit from 50 km/h to 30 km/h in certain parts of the road network of Athens, Greece. A questionnaire was developed based on the method of stated preference for various hypothetical scenarios of time, fuel consumption and the probability of road crash to investigate road user preferences towards the reduction of speed limit and identify the most important influencing factors preferences. A total of 408 respondents were asked to choose among three alternative proposals: a) Reduce the speed limit to 30 km/h throughout the urban network except on major arteries, b) Reduce the speed limit to 30 km/h throughout the urban network and c) No Reduction (do nothing). For the analysis, two binomial logistic regression models and two multinomial logistic regression models were developed. The results indicate that increase in travel time, the importance of speed in causing a crash, the number of crashes the user has been involved in, the respondent’s driving habits are the main determinants of the users’ preferences. Furthermore, a Cost Benefit Analysis (CBA) was conducted to understand the sustainability implications of the implementation of lower speed limits (i.e., 50 to 30 km/h). In terms of socio-economic impacts, the CBA considered safety-related metrics, namely the number of road casualties of all severity levels, and environmental-related metrics, namely reductions in CO2, NOx, PM levels as well as in road user surplus metrics namely travel time increase and fuel consumption reduction. Costs considered in the analysis result from increased time spent on the road. Consequently, the investment and the operational costs along with the socio-economic impact are estimated and monetized, up to the year 2030. The positive Net Present Value (NPV) and the high Internal Rate of Return (IRR), i.e. 64.5 %, obtained as well as the sensitivity analysis results, indicate the feasibility of this policy over time. Therefore, speed limit reductions are economically viable and so, should be encouraged.