Traffic safety for cyclists in roundabouts: geometry, traffic, and priority rules: A literature review

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The aim of this study was to carry out a literature review of roundabout geometric characteristics and traffic management regulations addressing the safety for cyclists. The literature review examined articles from 1990 until 2017. An article was considered relevant as follows:

  • Investigation of the relationship between roundabout geometric design and cyclist accidents (2 articles)
  • Investigation of the relationship between roundabout geometric design and cyclist operation/interaction with other traffic, i.e., motorised vehicles (4 articles)
  • Investigation of any safety impacts of the conversion of intersections into roundabouts for cyclists (9 articles)
  • Psychological/behavioural studies of cycling at roundabouts (5 articles)

The results show that the impact on cyclist safety is not as clear as for motorised vehicles with some studies showing a deterioration for cyclists (Jensen, 2013; 2016; Daniels et al. 2008; 2009). The cycle facility type (e.g., mixed traffic, cycle lane, and cycle path) and the priority rules have the potential to increase safety for cyclists. For example, the priority rules vary among different countries and within some countries.

From the literature, which priority rules provide the safest cycling environment remain unclear in terms of number of accidents and injury severity. The identified priority strategies are: (i) cyclists always yield to vehicles, (ii) shared yielding responsibility, (iii) vehicles always yield to cyclists, and (iv) an alternate solution ‘with’ and ‘without’ priority based on special characteristics (e.g., presence of vulnerable road users, geographic location). Furthermore, cycle lanes are the most unsafe cycle facility compared to mixed traffic or cycle paths. Likewise, coloured cycle lanes at roundabouts are less safe than non-coloured cycle lanes (Jensen, 2016). On the other hand, it is recommended that cyclists should ride in front of or behind vehicles in mixed traffic at single-lane roundabouts and in the middle of the lane, and should not ride parallel with vehicles (Cumming, 2012).

Some research directions are highlighted. The impact of the different priority rules needs further investigation in terms of number of accidents and injury severity. Some questions to study include: (i) what the best priority strategy is; (ii) what special road markings should be used; (iii) what the best distance is to place the cycle path from the circulatory roadway. Another research direction is to establish the impact on cyclist safety of cycle lanes at roundabouts. Finally, the impact on traffic safety, by cycling in the middle of the lane, needs further investigation as well.

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