University of Twente Student Theses


Effects of speed limit reduction on safety, job accessibility and equity : Case study: Amsterdam, speed limit reduction of 50km/h to 30km/h

Beek, M.C. (2022) Effects of speed limit reduction on safety, job accessibility and equity : Case study: Amsterdam, speed limit reduction of 50km/h to 30km/h.

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Abstract:Safety-improving countermeasures, such as speed limit reduction policies, often result in higher travel times, but the true effect of these policies on accessibility has remained unknown. Usually, the external costs of transport, like traffic crashes, are neglected in the accessibility analyses in both research and practice. Decreasing the maximum speed is not an unknown measure to improve traffic safety. This research examined how reducing the speed limit, from 50 to 30 km/h, effects job accessibility by car and bicycle in different postcode areas, in the municipality of Amsterdam. This is done by integrating traffic crash risks as a cost component in an accessibility model. Additionally, this research investigated how the impacts of speed limit reductions will be distributed over different areas that differ in terms of the total population aged between 15 and 65, income levels, household sizes, gender and immigration background. The new accessibility model was applied in a scenario analysis based on which the equity impacts of the proposed policy were examined by comparing the impacts of the new policies on changes in the potential job accessibility for car and bike users. For predicting the number of car-to-car and car-to-bicycle crashes with property damage only (PDO) and killed or severely injured (KSI) crash results, a negative binomial model and an empirical Bayes method were used. A power model is used to determine the effects of speed limit reduction on the number of crashes during the morning and evening peak hours. Based on the crash risks and the traffic volume a monetary value is determined for each road segment. The total costs for a road segment are based on this monetary value for crash risk and the travel costs, which are determined based on the travel costs and value of travel time. Then an accessibility model using the contour measure determined the number of jobs that could be reached within a threshold. With the help of a spatial analysis method, Local Moran’s I analysis, is determined whether the potential job accessibility is clustered or randomly scattered over the study area. Moreover, to recognize the effects of speed limit reduction on certain population groups in Amsterdam the bivariate Moran’s I analysis was performed. With the visualization of this analysis, the equity of accessibility change in Amsterdam for the different population groups could be determined. This research concludes that speed limit reduction reduces the accessibility of most car users while most bicyclists will experience an increase in accessibility. From an equity point of view, with the current accessibility there are clear clusters visible with high accessibility as well as clusters with low accessibility. The policy measure to reduce speed limit is most disadvantaged for car users living in regions with a high percentage of males. For other variables such as the number of active population, median income, average household size and percentage of non-western immigrants, no clear group is benefiting more than other groups. The same five variables were tested on equity for changes in bicycle accessibility and showed that the regions with a high percentage of male inhabitants are negatively affected when it comes to cycling accessibility. Again no indication for the other variables showed that one group is more beneficial than another group.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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