Roundabouts
Roundabouts, a type of intersection control, can offer safety benefits for all road users, including motorcyclists, by reducing conflict points and lowering vehicle speeds. They can contribute to a safer road environment for riders.
Detailed explanation
Traditional intersections with traffic signals create multiple potential conflict points where vehicles can collide (e.g., left turns across oncoming traffic). Roundabouts reduce these conflict points by eliminating left turns across traffic and replacing them with a continuous flow of traffic in a circular direction. This reduces the likelihood of head-on and T-bone crashes, which are often severe. Furthermore, roundabouts require drivers to slow down as they approach and navigate the intersection, which can be particularly beneficial for motorcyclists, giving them more time to react to potential hazards.
Types of Roundabouts
Simplest form, with a single circulating lane.
Have two or more circulating lanes, requiring drivers to choose the appropriate lane upon entry.

Smaller roundabouts often used in residential areas or low-speed roads.
how/when to apply
Roundabouts can be considered for intersections with high crash rates, particularly those involving angle or head-on collisions. They are also suitable for locations with high traffic volumes or where traffic calming is desired. Analyzing crash data, including motorcycle crashes, can help determine the suitability of roundabouts for a particular location.
Key Takeaways
Pros
- Reduced Conflict Points: Eliminates left turns across traffic, reducing the potential for head-on and T-bone crashes.
- Lower Speeds: Requires drivers to slow down, giving riders more time to react to potential hazards.
- Improved Traffic Flow: Can improve traffic flow compared to traditional intersections, reducing congestion. Up to 75% more efficient than a signal.
- Potential for Reduced Injuries: Studies suggest that roundabouts can reduce the severity of crashes.
- Provide more resiliency than signals, which fail during storm events due to power loss.
Cons
- Land Requirements: Roundabouts can require more land at the corners of the intersection, than traditional intersections, but can eliminate the need for land on the approaches for turn lanes.
- Rider Confusion: Riders unfamiliar with roundabouts may experience confusion, particularly in multi-lane versions.
- Driver Confusion: Drivers unfamiliar with roundabouts may experience confusion leading to abrupt last-minute maneuvers.
- Cost: Construction of roundabouts can be more expensive than traditional intersections, for the initial construction, but reduce or eliminate the need for signal maintenance and retiming.
- Potential for Low-Speed Crashes: While reducing severe crashes, there is a potential for minor low-speed incidents within the roundabout itself.
Design manuals
Design Manual 1
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Design Manual 2
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Design Manual 3
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Resources
Accordion #1
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