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National and State studies show that roundabouts increase safety and reduce delay.
Over 1,000 modern roundabouts have been built in the United States since 1990.
Roundabouts are a proven strategy to reduce injury and fatal crashes compared to traditional intersections. Roundabouts are effective at slowing down traffic so that when crashes do occur, they usually occur at low speeds and are unlikely to cause injury or major damage. Roundabouts are also able to prevent head-on and right angle (T-bone) types of crashes, which are among the most deadly crash types due to the rapid transfer of energy between colliding vehicles.
Although traffic signals provide lights that indicate when a pedestrian has the right-of-way, pedestrians crossing at traffic signals must still be vigilant of drivers making yielding left turns or making right turns on red, and drivers too often make tragic mistakes such as running red lights, often at high speeds. Roundabouts offer pedestrians much lower traffic speeds, better sight lines, much shorter crossing distances, and much less waiting time before being able to cross, putting pedestrians in greater control of their own safety.
Traffic signals usually require left and right turn lanes in order to operate safely and effectively, and the costs of constructing turn lanes where they do not already exist can make traffic signal implementation significantly more expensive than a roundabout. For example, US61 and 170th Street in the City of Hugo, the roundabout cost $1.2 million to construct in 2013, but the costs of constructing turn lanes and a traffic signal was estimated at $2.0 million. Because fewer approach lanes are needed at roundabouts, the project length and property impacts can also be significantly lessened, reducing or eliminating the need for property acquisition (eminent domain).
At locations where traffic volumes are relatively balanced between the intersecting roadways, roundabouts can often handle traffic with much less delay than a comparable traffic signal. A 2010 county study compared the signalized intersection of 10th Street and Inwood Ave in Lake Elmo with the roundabout intersection at Radio Drive and Bailey Road in Woodbury during the afternoon rush hour. Although the intersections have very similar traffic volumes, the study found that drivers at the roundabout incurred 58% less delay than at the traffic signal, despite the fact that the traffic signal has sixteen approach lanes while the roundabout has only eight.
Multilane roundabouts function like a traffic signal with multiple lanes. Signs are placed along the roadway prior to the roundabout, informing motorists of the movements that are allowed in each lane.
For instance, at a signal, left turns are generally not allowed from a right lane and right turns are not allowed from a left lane. The same is true in a multilane roundabout. Always follow the signs to choose the correct lane.
Traffic Circles vs RoundaboutsRotaries vs Roundabouts
Roundabouts are designed so that buses may go through them while staying in their own lane. Larger roundabouts allow large semitrailers to go through while staying in their lane as well. However, most roundabouts have a raised concrete apron around the inside circle to allow trucks to ride over them. This allows trucks to go through the roundabout while allowing the roundabout to stay small in size.
You should proceed through the roundabout prior to pulling over for the emergency vehicle to pass. If you are approaching a roundabout, pull over before entering to allow the emergency vehicle to pass you. Never stop within the roundabout, as doing so may obstruct the path of the emergency vehicle and prevent other vehicles from exiting.
Roundabouts typically take more room than traffic signals at low-volume intersections. As volume increases, the size of a roundabout and traffic signal become comparable. However, because roundabouts do not require the construction of turn lanes to store vehicles waiting for a green light, they allow the roadways entering the roundabout to be narrower, this reducing property impacts.
In rural areas, drivers are normally able to pass pedestrians who are lawfully walking along the roadway or shoulder. However, the design of roundabouts omits shoulders and prevents drivers from passing in order to ensure safe operating speeds. In this constrained geometry, drivers would be unable to pass any pedestrians who were walking within the roundabout. Therefore, even in rural areas, roundabouts typically feature separated sidewalks and crosswalks to ensure safe and efficient operations for drivers and pedestrians.
Entering a roundabout is similar to an intersection between two one-way roads, where the road from the left continues out of the roundabout. To proceed into the roundabout, entering drivers must yield to all traffic from the left, waiting until all traffic from the left is clear.
Entering drivers are not permitted to enter alongside cross traffic, because both lanes of cross traffic are allowed to exit the roundabout. Entry is neither a “right turn” nor a “merge”.
Extra signs mounted below the yield signs remind drivers to yield to both lanes. Never enter unless all traffic from the left is clear.
As with any other intersection, the proper lane must be chosen before entering a roundabout. Signs in advance of the intersection will always indicate which lanes may be used to turn or to continue ahead. As with any other intersection, keep left to turn left through the roundabout, and keep right to turn right. Never change lanes within an intersection, including within roundabouts.