Bicycle safety at roundabouts

An Australian and New Zealand crash analysis found that most of the crashes occurred at urban local road roundabouts, in 50 km/h speed limit zones. The crashes predominantly occurred on the circulating lane near the entry for an approach road and were right-adjacent type crashes. The study included an in-depth investigation of 17 roundabouts across Queensland, New South Wales and Victoria. A geometric analysis identified that the entry geometry of the roundabouts investigated would permit relatively high entry speeds, in excess of the target speed of less than 30 km/h. This target speed was adopted for analysis purposes, however, further investigation to determine an appropriate speed to prevent or minimise fatal and serious injury outcomes for crashes involving motor vehicle and cyclists is needed. The motor vehicle speeds on the entry and circulating lanes were estimated using the ARNDT crash prediction model, however the model was developed on rural roads and so the application of this model to urban local roads requires verification. For the purposes of this investigation, the ARNDT model was used to assess geometric alignments to achieve lower approach speeds and it was found that a roundabout with a radial-type of alignment, used in countries in Europe, achieved approach and circulating speeds of less than 30 km/h. Sight distances were examined and it was found that the available sight distance to vehicles approaching from the right did not meet the design requirements. There is some research which indicates that restricting the sight distance on the approach to a roundabout reduces the approach speeds of vehicles, however, this requires further investigation to develop design criteria. The report recommends further investigation into motor vehicle/cyclist crash outcomes and the effect of restricting sight distance on the approaches to a roundabout, and the development of design guidance for urban local road roundabouts.