Roundabouts considered for multilane roads
by Ken Johnson, Mn/DOT
Ed. note: The winter 2005 Exchange article titled "Engineering solutions—working together for Minnesota" incorrectly cited Ken Johnson's presentation at the Toward Zero Deaths Conference. Following is what we should have printed. Our apologies to Johnson and our readers.
Modern roundabouts are a traffic control device that can be used in many intersection locations that have traditionally been signalized. They can handle traffic volumes up to 8,000 vehicles per hour; however, these larger volumes need multilane roundabouts. Many agencies have taken a "slow and easy" approach that will only consider single-lane roundabouts until quite a few have been constructed, after which that agency will consider multilane applications. Other agencies have jumped right in and constructed multilane roundabouts from the beginning. Wisconsin DOT, for instance, has four operating multilane roundabouts on the state highway system. Studies have shown that while the overall crash rate of a multilane roundabout is only slightly less than that of a signalized intersection, the injury crash rate is significantly reduced.
Mn/DOT currently has a moratorium on multilane roundabouts on the State Aid system; however, there are locations on the state highway system for which Mn/DOT staff are considering multilane applications.