A roundabout is a form of intersection design and control which accommodates traffic flow in one direction around a central island. It operates with yield control at the entry points and gives priority to vehicles within the roundabout.
Maplewood constructed its first roundabout in 2002 at the intersection of Frost Avenue and English Street as part of the English Street Improvement city project. It has been fully operational since October of 2002.
A standard four-way intersection has 32 potential collision points when all the turning movements from each of the roadway approaches are counted; roundabouts have only eight potential conflict points.
The center island of a roundabout also eliminates the possibility of head-on collisions. The English/Frost intersection will generally have 1.0 million vehicles entering every 45 days. The intersection had four to eight accidents each year and two were classified as serious.
Maplewood city officials anticipate that accidents at this intersection could be reduced by 33 percent with the addition of the roundabout and none of these collisions should be serious.
The curving nature of the roundabout approaches and the inner circular island require travel speeds to be low to maneuver through the intersection.
According to guidelines established by the Federal Highway Administration, speed in a roundabout on a minor roadway, such as the intersection of Frost Avenue and English Street in Maplewood, is restricted to 15 mph. This slower speed also requires smaller gaps in the circulating traffic for vehicles trying to enter the roundabout.
A typical intersection signal system costs $200,000 and takes 2-3 years of study, planning and fabrication time before it can be installed. The cost of the roundabout at English Street and Frost Avenue was about $150,000 to install. In addition, the roundabout does not require electricity to operate.
Roundabouts also create much less delay and pollution than other traffic control devices, have a higher vehicle capacity, and require very little maintenance.
Correct Way to Drive
The roundabout at Frost Avenue and English Street is governed by a "yield-at-entry" rule that requires all vehicles entering the roundabout to yield to traffic circulating within the roundabout. This allows the roundabout to maintain traffic flow even with high traffic volumes.
- Reduce your speed when approaching the roundabout. The speed limit on both Frost Avenue and English Street is 30 mph, while the limit within the roundabout is 15 mph.
- When reaching the roundabout, yield to traffic circulating from the left. Watch out for cyclists and motorcyclists. Do not enter a roundabout when an emergency vehicle is approaching on another leg.
- Within the roundabout, do not stop except to avoid a collision; you have the right-of-way over entering traffic. Always keep to the right of the central island and travel in a counterclockwise direction.
- Maintain a slow speed upon exiting the roundabout. Always indicate your exit using your right-turn signal. If going straight ahead (exiting at the halfway point or more around the roundabout), do not use your signal until just before the exit you will use. Yield to pedestrians waiting to cross, or crossing, the exit leg.