University of Twente Student Theses


How to keep credibility? The transition from 50 km/h to 30 km/h within the urban area

Kessel, J. van (2020) How to keep credibility? The transition from 50 km/h to 30 km/h within the urban area.

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Abstract:In recent years there has been more and more discussion about speed limits in built-up areas. One of the most discussed proposals is to transform 50 km/h roads to 30 km/h roads. 30 km/h should become the new standard within built-up areas according to certain organisations. The most frequently mentioned argument for this speed limit reduction is road safety. At lower speeds, the severity of many accidents is lower, resulting in fewer (fatal) casualties. A lower speed would also contribute to an improved living environment, for example by reducing traffic noise pollution. However, in order to benefit from the advantages of a possible speed reduction, drivers must adapt to the new limit and reduce their speed. On many 30 km/h roads, speeding is still excessive. The incredible design of roads contributes to this. Changing a 50 km/h sign to a 30 km/h sign is not enough, the road will also have to be adapted to make the limit credible. Different road and environmental characteristics play an important role in this process and determine whether the image of the road and surroundings matches the speed limit. The number of studies into the credibility of the speed limit on 30 km/h roads is still very limited. Most studies into a credible design are aimed at roads with higher speed limits. Therefore, it was decided to investigate which road and environmental characteristics influence the credibility of 30 km/h roads, so that these roads can be designed more credibly. The core of the research consists of a survey in which respondents (car drivers) were shown photographs of a selection of 30 km/h roads. For each road, the respondent was asked about the preferred speed and estimated limit. The credibility has been quantified as the difference between these speeds and the speed limit. In addition to the survey, literature research was carried out to find out which road and environment characteristics from earlier studies influenced the credibility and speed. These characteristics were collected for the selection of 30 km/h roads from the survey. Finally, the respondents' speeds and the characteristics of the roads were combined in data analysis to determine the influence of the individual road and environmental characteristics on the credibility. Multiple regression analyses with combinations of relevant characteristics were also carried out. In this way, the effect of the individual characteristics in conjunction with other characteristics on credibility was assessed. The results show that environmental characteristics have the most influence on credibility. Roads with shops, connected buildings and buildings on both sides of the road are characteristics that contribute most to credibility and reducing speed. Additionally, various characteristics of the road have a significant influence on credibility, especially the presence of parked cars and the location of cyclists (mixed with other traffic instead of bicycle lanes). Moreover, an existing method for comparing the credibility of roads was tested. However, the credibility scores of roads turn out to have no relation whatsoever with both the speeds of respondents and the measured speeds. For this reason, a new tool, a credibility indicator, has been developed that can be used to determine the credibility of 30 km/h roads more accurately. This indicator is based on the results of the data analysis and requires some road and environmental characteristics to be entered. After the entry of these characteristics, an indication of the credibility is directly displayed on a speedometer with colour scales. The research can be classified as exploratory research and offers sufficient starting points for possible follow-up research. For example, the number of 30 km/h roads in the survey was limited, meaning that the influence on credibility could not be determined for all characteristics. Insufficient observations were made of some of the characteristics, resulting in an unknown influence on credibility. Follow-up research with a larger group of roads, therefore, leads to more diversity of characteristics, resulting in a more complete overview of the influence of characteristics on credibility. With these new insights, the existing credibility indicator can also be expanded.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Programme:Civil Engineering and Management MSc (60026)
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