Road safety aspects must not be overlooked in the design of roundabouts

Jun 2017

Infrastructure

In many countries in Europe, roundabouts have enjoyed something of a renaissance since the 1990s. The lower speed on roundabouts has helped to reduce both the number of accidents and, in the event that an accident occurs, the severity of injuries suffered. But roundabouts are not always the best solution, and, where the general conditions are unfavorable, they do not always improve safety either. Like other infrastructural measures, roundabouts also need to be announced well in advance. Especially at night, drivers need to be informed about an upcoming roundabout clearly and early on – for example, with good signage, adequate road lighting or retroreflective markings.

As a study conducted by the TU Dresden on behalf of the German Federal Highway Research Institute showed, poor recognizability of roundabouts during rainy or wet conditions leads to an increase in accidents specifically involving riders of motorcycles and bicycles, whom motorists either do not see at all or see only when it is too late. To put this in figures, one in two roundabout- based accidents investigated by the study occurred during wet conditions, and around one in three involved cyclists. In addition, the entrances and exits should be designed such that they force drivers to slow down, and the sculptures and other forms of art installed in the center of some roundabouts must not constitute a hazard or distract drivers.

What is particularly baffling is that different rules regarding priority on roundabouts still apply in Europe. In Germany, for example, traffic about to enter the roundabout has to wait for traffic already on the roundabout; drivers indicate only when exiting the roundabout. In Austria, the “right before left” rule applies – that is, traffic about to enter the roundabout has right of way over traffic already on the roundabout, although special signage may stipulate deviations from this rule where necessary; drivers indicate when exiting the roundabout. In Italy, the “right before left” rule also applies. In practice, however, it is frequently ignored, which is why extra care is required. In France, vehicles about to enter the roundabout always have priority, although special signage can often be seen stipulating that traffic already on the roundabout has right of way. In Switzerland, Spain, Portugal and Poland, the traffic already on the roundabout has right of way (unless otherwise specified). In the UK, where you drive on the left, vehicles enter roundabouts from the left. The traffic on the roundabout coming from the right usually has right of way.

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