Roundabouts for Beginners

Single Lane Truck Brochure
Single Lane Truck Brochure (PDF)
Single Lane Benefits Brochure
Single Lane Benefits Brochure (PDF)










Facts and Myths

This section provides a high level view of what a roundabout is; how and why they work better than a typical four way signalized intersection in the right applications.

Single Lane Ped Bike Brochure
Single Lane Ped Bike Brochure (PDF)







Dispelling the Common Myths about Roundabouts

Myths Facts
roundabouts and traffic circles/rotaries are the same thing. While they may share a similar appearance, the design and operation of are quite different.Rotaries, predominantly found in the northeastern US, and European traffic circles are large diameter circles with high-speed entries, variable yield rules, low capacity, and many high-speed crashes. They are typically regarded as dangerous and confusing to drive.Roundabouts require motorists to yield on entry, speeds are low, capacity is high, and crashes are few and minor in severity. They are regarded as easy and comfortable to drive.
roundabouts cause more crashes than other intersections. According to the Insurance Institute for Highway Safety, roundabouts significantly reduce motor vehicle crashes. Their 2001 study reviewed 24 converted intersections around the U.S. At those intersections, all crashes were reduced by 30-40%. Serious crashes reduced by 75%, and fatal or incapacitating crashes by 90%. Follow-on analysis in 2004 and 2007 have confirmed these findings, and indicated slightly higher reductions.
roundabouts are not pedestrian friendly. There are statistically fewer pedestrian crashes at roundabouts than at signalized intersections. At roundabouts, vehicle speeds are much slower and drivers sight lines are directed towards pedestrians in and adjacent to the crosswalks, while raised splitter islands provide a space for pedestrians in the middle of each crossing so pedestrians only need to cross one direction of traffic at a time.
semi-trucks and farm equipment will not be able to maneuver through the roundabout. Large vehicles have a direct impact on the design of a roundabout. Single-lane roundabouts employ a traversable apron (“truck apron”) around the perimeter of the central island to provide the additional width needed for tracking the trailer wheels of large vehicles such as the standard highway tractor-trailer combination with a trailer.  The same applies for farm equipment and other trucks not requiring permits or escorts to travel the roads.In some instances, the routes are designated for even larger oversize trucks. In those cases, roundabouts have been designed with aprons, additional mountable surfaces, or gated roadways through the central island to accommodate over-sized trucks, emergency vehicles, or combination vehicles.
new drivers and elderly drivers will not be able to drive safely through the roundabout. One of the key design features of a roundabout is that all traffic must slow down as it enters the intersection. Slower speeds can benefit both the novice and older driver as they navigate the roadways. Some of the potential benefits of slower intersection speeds include a reduction in crash severity (for a given crash type), safer merges, and more opportunities to correctly judge and enter gaps.  The slower and consistent speeds at roundabouts can cater to the preferences of older drivers by:

  • Allowing more time to make decisions, act, and react;
  • Providing less complicated situations to interpret;
  • Requiring simpler decision-making;
  • Reducing the need to look over one’s shoulder;
  • Reducing the need to judge closing speeds of fast traffic accurately; and
  • Reducing the need to judge gaps in fast traffic accurately.

The benefits a roundabout provides to older drivers can be an important factor in reducing the number of crashes at an intersection.

Choose your mode of transport using the interactive menu on the left to view instructions on using a roundabout.

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Implementing the Central Healdsburg Avenue Plan