Study Details

Study Title: Safe roundabouts for cyclists

Authors: Jensen, S. U.

Publication Date: 2017

Abstract: May roundabouts be safer for cyclists than intersections? How are safe roundabouts designed? This paper tries to answer these questions on the basis of a before-after safety study of conversions of intersections to 255 single-lane roundabouts in Denmark. The before-after study accounts for long-term accident and injury trends and regression-to-the-mean effects. In order to relate safety effects for cyclists of various roundabout design features it is crucial to split the converted sites by speed limit, because safety effects for both cyclists and other road users of converting intersections to roundabouts depend heavily on speed limits on roads entering the converted sites. If speed limits are 70 km/h or higher then converting intersections to roundabouts have resulted in bicycle safety improvements in Denmark. Results show that diameter and height of central islands and type of bicycle facilities at single-lane roundabouts have considerable impacts on cyclists’ safety. Central island diameters of 20–40 m are safer for cyclists than smaller or larger roundabouts. A central island, which middle is elevated 2 m or more above the circulating lane, is safer for cyclists than single-lane roundabouts with lower central islands. Single-lane roundabouts with separate cycle paths, where cyclists must yield to motorists entering or exiting the roundabout, are safer than roundabouts with cycle lanes. Single-lane roundabouts are safer for cyclists than intersections regardless of speed limits when these roundabouts have high central islands and/or separate cycle paths.

Study Citation: Jensen, S.U. "Safe roundabouts for cyclists". Accident Analysis and Prevention, Vol. 105, (2017) pp. 30-37.

Study Report: Download the Study Report Document

Comments: This review excluded CMFs with zero expected crashes and zero observed crashes as the Clearinghouse team did not feel that these were implementable findings.

CMFs Associated With This Study

Category: Intersection geometry

Countermeasure: Conversion of intersection into single-lane roundabout

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.48522 StarsOtherAllNot specifiedRural
0.54462 StarsOtherAllNot specifiedRural
0.51493 StarsOtherAllNot specifiedRural
2.67-1672 StarsVehicle/bicycleAllNot specifiedAll
3.39-2392 StarsVehicle/bicycleAllNot specifiedAll
2.89-1892 StarsVehicle/bicycleAllNot specifiedAll
0.53472 StarsVehicle/bicycleAllNot specifiedAll
0.5502 StarsVehicle/bicycleAllNot specifiedAll
2.33-1332 StarsVehicle/bicycleAllNot specifiedAll
0.73272 StarsOtherAllNot specifiedAll
0.84162 StarsOtherAllNot specifiedAll
0.78222 StarsOtherAllNot specifiedAll
0.39612 StarsOtherAllNot specifiedAll
0.39612 StarsOtherAllNot specifiedAll
0.67332 StarsOtherAllNot specifiedAll
2.62-1622 StarsVehicle/bicycleAllNot specifiedAll
1.2-202 StarsVehicle/bicycleAllNot specifiedAll
1.53-532 StarsVehicle/bicycleAllNot specifiedAll
1.11-112 StarsVehicle/bicycleAllNot specifiedAll
1.11-112 StarsVehicle/bicycleAllNot specifiedAll
1.48-482 StarsVehicle/bicycleAllNot specifiedAll
0.9282 StarsOtherAllNot specifiedAll
0.44562 StarsOtherAllNot specifiedAll
0.57432 StarsOtherAllNot specifiedAll
1.44-442 StarsOtherAllNot specifiedAll
1.44-442 StarsOtherAllNot specifiedAll
0.72282 StarsOtherAllNot specifiedAll
01002 StarsAllAllNot specifiedUrban
01002 StarsVehicle/bicycleAllNot specifiedUrban
01002 StarsVehicle/bicycleAllNot specifiedRural
01002 StarsVehicle/bicycleAllNot specifiedAll
01002 StarsOtherAllNot specifiedAll
1.06-62 StarsAllAllNot specifiedUrban
0.85152 StarsAllAllNot specifiedUrban
1.34-342 StarsAllAllNot specifiedUrban
0.78222 StarsAllAllNot specifiedRural
0.53473 StarsAllAllNot specifiedRural
0.81192 StarsAllAllNot specifiedRural
0.75253 StarsAllAllNot specifiedAll
0.68322 StarsAllAllNot specifiedUrban
0.54462 StarsAllAllNot specifiedRural
0.41593 StarsAllAllNot specifiedRural
0.9462 StarsAllAllNot specifiedRural
0.52483 StarsAllAllNot specifiedAll
2.73-1732 StarsVehicle/bicycleAllNot specifiedUrban
1.88-882 StarsVehicle/bicycleAllNot specifiedUrban
2.24-1242 StarsVehicle/bicycleAllNot specifiedUrban
1.75-752 StarsVehicle/bicycleAllNot specifiedRural
1.1-102 StarsVehicle/bicycleAllNot specifiedRural
2.03-1032 StarsVehicle/bicycleAllNot specifiedAll
0.71292 StarsVehicle/bicycleAllNot specifiedUrban
0.38622 StarsVehicle/bicycleAllNot specifiedRural
0.69312 StarsVehicle/bicycleAllNot specifiedRural
0.56442 StarsVehicle/bicycleAllNot specifiedAll
2.02-1022 StarsVehicle/bicycleAllNot specifiedUrban
2.33-1332 StarsVehicle/bicycleAllNot specifiedUrban
1.48-482 StarsVehicle/bicycleAllNot specifiedUrban
0.36642 StarsVehicle/bicycleAllNot specifiedUrban
1.98-982 StarsVehicle/bicycleAllNot specifiedUrban
0.55452 StarsOtherAllNot specifiedUrban
0.67332 StarsOtherAllNot specifiedUrban
0.72282 StarsOtherAllNot specifiedUrban
0.61392 StarsOtherAllNot specifiedUrban
0.66343 StarsOtherAllNot specifiedUrban
2.25-1252 StarsVehicle/bicycleAllNot specifiedRural
1.02-22 StarsVehicle/bicycleAllNot specifiedRural
0.19812 StarsVehicle/bicycleAllNot specifiedRural
0.85152 StarsVehicle/bicycleAllNot specifiedRural
0.42582 StarsOtherAllNot specifiedRural
0.52482 StarsOtherAllNot specifiedRural