Reduction in fuel use
	Reduction in pollution
	No signal equipment to install and repair
	Reduction in noise due to fewer stops/starts (quieter neighborhoods)

The safety features of the modern roundabout overcome initial skepticism and contribute to their growing popularity.

Studies reporting dramatic reductions in fatal crashes, injury crashes and pedestrian crashes attributed to modern roundabouts are very impressive.

Arizona and the City of Phoenix have the nation’s worse scores for fatalities resulting from red light runners at traditional intersections! Modern roundabouts -- a one way circular intersection without signals -- are designed to reduce this grim statistic by slowing down and calming traffic.

Like any new development, modern roundabouts inspire questions. Some of the most common inquiries are discussed in the following sections. And, of course, if your questions are not answered below, simply contact ADOT. We welcome the opportunity to answer you directly.

No a modern roundabout is not a 4 way stop. Both intersections are what the engineering community calls a “method of moving traffic”. Four way stops require all traffic to stop prior to entering the intersection. Modern Roundabouts require motorists to YIELD at entry ways. All traffic entering a modern roundabout must follow the golden rule of the modern roundabout; Motorists entering a modern roundabout never merge.

All motorists approaching a roundabout must slow down and yield. Other differences between roundabouts and 4 way stop intersections include:

	Four way stops yield to the right while roundabouts yield to the left (similar to a right turn on red.) This pattern is dictated by the fact that circulating traffic in a roundabout comes from the left.
	Traffic in a Modern Roundabout circulates counter clockwise.
	Motorists coming from different directions get a turn in order at a four way stop. This is not the case with roundabouts where each driver chooses a safe gap to enter rather than taking a “turn”.

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. This is due to the fact that a pedestrian crossing is reduced to two simple crossings of one way traffic proceeding at relatively slow speeds.

Pedestrian safety is enhanced by the presence of a Pedestrian Crosswalk sign placed right before a vehicle enters a modern roundabout. Even with this precaution, it is recommended that pedestrians use caution and always use the designated crosswalk.

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

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

For more information regarding pedestrian and bicycle use of modern roundabouts, consult the subsection in the Users Guide.

These vehicles are subject to the same rules as cars, trucks, etc. Motorcycle and motor bike riders should consult the Users Guide, with special attention being paid to the subsection entitled 'How to Drive a Modern Roundabout'.

Modern roundabouts are designed to accommodate emergency and other large vehicles. If the roadway is wide enough, pull over as far to the right as possible and let the vehicle pass. Whenever possible, completely clear the modern roundabout and pull off to the side.

Any time lost negotiating the modern roundabout -- where speeds are 15-25 mph will only be a few seconds.

For more information, check out the Users Guide.

The price tag of modern roundabouts versus traditional more familiar methods of moving traffic through intersections can vary. Demographics, geography and environmental elements all come into play when engineers and planners begin to consider how to move traffic through from one street to another. The variables in the decision making process, community involvement and growth patterns influence how transportation professionals and city and state planners make decisions about how to move traffic.

Sometimes the price tag for right of way acquisition is higher than the price tag of traffic signal construction and sometimes it is not a factor.

Modern roundabouts do not require traffic light electricity, but the maintenance of landscaping or public art is a cost.

The construction of modern roundabouts is not a panacea for all new traffic intersections, like other ways to move traffic through intersections it is a tool in a tool box increasing numbers of Departments of Transportation in the USA are beginning to take a serious look at.

The Insurance Institute for Highway Safety statistics show there are fewer serious accidents in Modern Roundabouts. There are fewer and fatal crashes in modern roundabouts.

When safety factors go up, the cost to society emotionally and physically goes down.

Modern roundabouts are not appropriate for use everywhere but if the community leaders in your area are considering a Modern roundabout ADOT will respond appropriately.

If you have questions about modern roundabouts near you call your local ADOT District, or take a look at the Arizona Modern Roundabouts page of to learn about which ones are currently under construction as well as sites being considered for future construction.