University of Twente Student Theses
Speed variables on Rijkswaterstaat N-roads and their relationship with crash likelihood and crash severity
Tacx, T.M.A. (2023) Speed variables on Rijkswaterstaat N-roads and their relationship with crash likelihood and crash severity.
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| Abstract: | Road safety is an important aspect of traffic management. Road safety is most often measured in fatal crashes. For governments and other road managers to determine how to decrease the number of fatal crashes on their roads, it is important to determine what factors influence crash likelihood and crash severity. This research aims to answer that question for several speed variables on roads managed by Rijkswaterstaat, specifically N-roads without physical separation (1x2 connected lanes) and with physical separation (2x1 separated carriageways). In addition to the speed variables (S85, deviation from the speed limit, standard deviation of speeds during two off-peak and two peak time periods, coefficient of variation of speeds on one road section), through literature review, several traffic and road characteristic variables (vehicle kilometres, freight percentage, lane width, shoulder width, verge design, median width, horizontal alignment, merging lane presence, junction density) were found to have a relationship with the dependent variables crash likelihood and crash severity. Furthermore, the interaction effects between speed and vehicle kilometres, speed and junction density, speed and verge design, speed and shoulder width, speed and horizontal alignment, and speed and lane width, were found to have a relationship with crash likelihood and crash severity. The statistical analysis showed that the standard deviation of speeds during the evening peak hours and the S85 of speeds are significantly correlated with crash likelihood, in addition to a median width of 1.0 through 2.0 metres and vehicle kilometres. When accounting for interaction effects, an additional relevant result is the statistically significant relationship between the interaction effect of the S85 and verge design and crash likelihood. However, no statistically significant relationships between speed variables and crash severity were found. The only statistically significant relationship was found between junction density and crash severity. The lack of results for crash severity is ascribed to data limitations. These data limitations warrant further research using other sources for crash data, in addition to further research being needed which takes a longer data period into account, looks at different ways to structure the data, researches the relationship between speed deviations and time of day, and verifies the relationships in this study with other data. Finally, based on the results, practical recommendations to which could decrease crash likelihood and crash severity include reducing speed deviations, redesigning verges, turning at-grade junctions into separated junctions, and avoiding narrow medians. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/97580 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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