Roundabout study provides guidance for improving safety

roundabout2Roundabouts are a fairly recent addition to road systems in the United States, and their relative newness has made them a topic of discussion and debate. While roundabouts dramatically reduce the incidence of fatal and severe-injury crashes compared to traditional signalized intersections, drivers continue to misunderstand the rules of the roundabout, resulting in improper use and avoidable collisions.

In a recent study, Researchers in the Minnesota Traffic Observatory (MTO) at the U of M examined driving behavior and safety before and after signing and striping changes were applied at a two-lane roundabout in Richfield, Minnesota.

This roundabout, built in 2008, exhibited an abnormal number of crashes after its completion. In response, local engineers experimented with changes in the roundabout’s signs and striping.

Researchers analyzed crash records and examined hundreds of hours of video to compare the crash rates and number of violations committed by drivers before and after the changes.

The findings indicate that the changes in signing and striping have made the Richfield roundabout safer. In particular, extending the solid line leading up to the intersection approach from 50 feet to 250 feet seems to have reinforced the message to drivers that they must select the correct lane before approaching the roundabout entrance. This reduces the occurrence of drivers turning improperly and the need for a driver to change lanes within the roundabout.

Another important finding was that the traditional fish-hook-style roundabout signs and complex striping patterns often cause confusion among drivers.

Immediately after the changes, the occurrence of improper turns decreased by 48 percent and incorrect lane choice was reduced by 53 percent. One year after the changes, the safety improvements were still significant.

Read the full article in the January issue of Catalyst.

Posted in Safety, Transportation research, Urban transportation

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