Increase in cycling accidents and accident risks of cyclists in big cities

Cycling volumes are increasing in many large cities around the world, including large Dutch cities. At the same time, these cities are experiencing a growing number of cyclists involved in serious road traffic crashes. SWOV researcher and UT PhD candidate Teun Uijtdewilligen aims to contribute to the understanding of how increasing cycling volumes in urban areas affect the objective and subjective safety of cyclists. The results show that with increasing exposure to cyclists, both the number of bicycle crashes and the crash risk of cyclists increases. The same effect is found for increasing exposure to motorised vehicles. 

Uijtdewilligen examined how cycling volumes and motorised vehicle volumes in the four largest Dutch cities (i.e. Amsterdam, Utrecht, Rotterdam, and The Hague) contribute to the number of serious injuries and fatal crashes and the perceived safety of cyclists. In addition, cycling infrastructure types, speed limits, network structure, and the built environment are considered as well.

Thesis

In this thesis , objective safety is captured by examining the number of fatal and serious injury bicycle crashes (i.e. crash frequency) and the probability of a bicycle crash occurring (i.e. crash risk) related to the exposure to cyclists and motorised vehicles (i.e. the number of cyclists or vehicles per unit road length). Since the level of exposure varies substantially between the hours of the day, hourly exposure metrics are used. Subjective safety is captured by examining the impact of crowding among cyclists on cyclists’ perceived safety.

Results

The results show that with increasing exposure to cyclists, both the number of bicycle crashes and the crash risk of cyclists increases. The same effect is found for increasing exposure to motorised vehicles. Moreover, while separated bicycle tracks are found to be the safest cycling infrastructure type in terms of objective safety, they are perceived as least safe when crowding among cyclists is high. Crowding, in general, negatively affects perceived safety of cyclists, in particular for older cyclists and women. It is also found that subjective and objective safety are correlated and that this relationship is affected by exposure to cyclists and motorised vehicles.

Since it is expected that cycling volumes in large cities keep increasing, it is important to invest in cycling infrastructure that is capable of safely facilitating large flows of cyclists and that separates cyclists from motorised vehicles.

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