Transportation Safety

Roundabouts

Frequently Asked Questions

What’s the difference between a traffic circle and a modern roundabout?

Many traffic circles require circulating vehicles to grant the right of way to entering vehicles and can be very large or very small. They can operate at higher speeds and often require motorists to move from one lane to another.

Modern roundabouts include improvements such as yielding to as opposed to merging with circulating traffic, deflection at entry and low-speed entry by design.

Is a modern roundabout like a four-way stop?

No, a modern roundabout is not a four-way stop. Both intersections are what the engineering community calls a “method of moving traffic,” but four-way stops require all traffic to stop prior to entering the intersection. Modern roundabouts require motorists to yield at entryways. All traffic entering a modern roundabout must follow the golden rule of the modern roundabout: Never merge. Here are some other differences between roundabouts and four-way stops.

  • Four-way stops yield to the right, while roundabouts yield to the left (similar to a right turn at a red light).
  • Traffic in a modern roundabout circulates counterclockwise.
  • Motorists coming from different directions take turns in a first-come-first-served order at a four-way stop. This is not the case with roundabouts, where each driver chooses a safe gap to enter.

How do I enter a modern roundabout when traffic is congested?

First, slow down! You should approach a modern roundabout at no more than 25 mph. Most importantly, do not merge. Always yield to traffic in circulation when entering a modern roundabout. Do not attempt to cut in front of traffic, but wait for a safe gap. The drivers already in the roundabout have the right of way.

Will modern roundabouts slow down traffic?

In most situations, a modern roundabout can handle higher traffic volumes with less delay than traffic signals because motorists do not stop for traffic lights. A two-lane roundabout will handle the same capacity as other major intersections in the Valley, and a three-lane roundabout handles up to 6,000 vehicles per hour.

Are roundabouts safe for pedestrians and bicyclists?

While it depends on the number of pedestrians and vehicles, in many instances, a modern roundabout can be safer for pedestrians than a traffic signal. Pedestrian crossing is reduced to two simple crossings of one-way traffic that is proceeding at relatively slow speeds. Pedestrian safety is improved further by the a pedestrian crosswalk sign placed right where a vehicle enters a modern roundabout. Even with this precaution, it is recommended that pedestrians always use caution and designated crosswalks.

Auto-pedestrian crash rates are usually lower at modern roundabouts than traffic signals. Also pedestrian injuries that do occur tend to be less serious because of the relatively low speeds demanded by modern roundabouts.

Properly designed modern roundabouts safely accommodate bicycles. Because vehicles are traveling at 15-25 mph, bicyclists can negotiate this traffic mode like a car.

What’s the price tag? Are modern roundabouts more costly to the taxpayer?

The price tag of modern roundabouts versus traditional traffic-control methods can vary. Demographics, geography and environmental elements all make a difference when engineers, communities, and city and state planners begin to consider how to move traffic from one street to another.

Sometimes the financial cost of right-of-way acquisition is higher than the cost of traffic signal construction, and sometimes it is not a factor. For example, though modern roundabouts do not require traffic-light electricity, the maintenance of landscaping or public art can be a cost. However, the reduction in fatal, injury and pedestrian crashes can reduce other costs, including car insurance premiums, health insurance premiums, and physical and emotional trauma. When safety factors go up, the cost to society goes down.