Scottsdale is a roundabout first city, which means that roundabouts are evaluated for effectiveness and feasibility in all projects that include intersections. According to the Federal Highway Administration, roundabouts are proven safety additions to transportation infrastructure, reducing severe crashes at intersections by up to 80 percent.

In addition to lowering collision rates, and severity of collisions, roundabouts reduce delays and lower emissions. The city's Roundabout First Policy was approved by City Council as part of the Transportation Master Plan in 2016.

One of the city's most successful multi-lane roundabouts is at Northsight Boulevard and Hayden Road. Built in 2014 as part of the Northsight Extension Project, the roundabout was designed to give travelers and efficient option to bypass the busy intersection at Hayden Road and Frank Lloyd Wright Boulevard. This roundabout is the busiest in the city, with approximately 35,000 vehicles going through it each day, it has reduced injuries and travel times in the area.

By understanding what a modern roundabout is and how it works, motorists, bicyclists, and pedestrians can travel through intersections easier and more safely.

ADOT Resources:

Motorists

Approach:

Reduce your speed to the posted speed. If you are approaching a multi-lane roundabout, choose the appropriate lane for your desired destination based on the signs and markings. Yield to pedestrians in the crosswalk; they have the right-of-way.

Enter:

Yield to vehicles in the roundabout. Wait for a gap in traffic and merge into traffic in the roundabout to the right.

Proceed:

Continue through the roundabout until you reach your street.

Avoid

Avoid stopping in the roundabout.

Exit:

Do not change lanes in a roundabout. Signal, then exit the roundabout to your right.

Yield:

To pedestrians in the crosswalk.

• For right turns, travel in the right land and exit based on the exit lane markings.
• For left turns, travel in the left lane.
• For continued forward travel, remain in the same lane you entered.

Pedestrians

Approach:

Look left at the designated crosswalk.

Cross:

Cross to the raised or painted triangular splitter or refuge island.

Look Right:

Finish crossing to the opposite sidewalk.

View map of roundabouts in Scottsdale

Multi-lane roundabout intersections

Existing:

• Hayden Road & Northsight Blvd.
• Princess Blvd. & Princess Drive
• 90th Street & Mustang Library Entrance

Planned:

• Scottsdale Rd. & Dynamite Blvd.
• Raintree Drive & Northsight Blvd.
• Hayden Road & Raintree Blvd.

Single-lane roundabout intersections

Existing:

• 60th Street & Dove Valley Road
• 64th Street & Lafayette Blvd.
• 68th Street & Cholla Street
• 70th Street & Oak Street
• 70th Street & Chaparral Road
• 74th Street & Sweetwater Blvd.
• 76th Place & Redfield Road
• 94th Street & Union Hills Blvd.
• 96th Street & Sweetwater Blvd.
• 96th Street & Cholla Street
• 100th Street & Cactus Road
• 104th Street & Cactus Road
• 104th Street & Cholla Street
• 108th Street & Cactus Road
• 118th Street & Rio Verde Drive
• 122nd Street & Rio Verde Drive
• 124th Street & Columbine Drive
• 124th Street & Cactus Road
• Osborn Road & Miller Road

What exactly is a roundabout?

Modern roundabouts must meet a minimum of three criteria:

1. All traffic must move counterclockwise around a raised, circular median. No traffic can travel through the center median.
2. The roundabout must be designed to keep traffic between 15 and 25 miles per hour.
3. All entering traffic must yield to traffic already in the roundabout. Besides yielding, no other type of traffic control, such as a light or stop sign, can control traffic in or entering the roundabout.

Are “roundabouts” different from “rotaries” and “traffic circles,” or are they all essentially the same thing?

They are not the same thing. Compared to roundabouts, rotaries are often much larger, encourage higher traffic speeds, can route traffic through the center circle and sometimes use a combination of yield signs, traffic lights and stop signs to control traffic. Traffic circles, on the other hand, tend to be much smaller than roundabouts and are designed primarily to force slower traffic speeds in a neighborhood.

Why are roundabouts often a safer alternative to conventional intersections?

Because traffic must travel around a raised median, roundabouts eliminate head-on and right-angle (T-bone) crashes, generally the two most severe types of accidents. Furthermore, the design of modern roundabouts forces traffic to travel at speeds below 25 miles per hour. With conventional multi-stop and signalized intersections, traffic can still speed, another common element in the most severe crashes.

While roundabouts may be a safer alternative, don't they increase drive times?

Because roundabouts permit the continuous flow of traffic, roundabouts typically result in reduced travel times.

Is the primary purpose of a roundabout to slow traffic?

While roundabouts encourage cars to travel at speeds of 15 to 25 miles per hour, the purposes of roundabouts are to improve safety, traffic flow and capacity at an intersection. Roundabouts are sometimes confused with traffic circles, whose primary purpose is to slow traffic in neighborhoods.

Are roundabouts more expensive to implement than other types of intersections?

While it does cost more to construct a roundabout than a four-way stop, it costs about the same to construct roundabouts and signalized intersections. Roundabouts, however, tend to be cheaper over time than signalized intersections because roundabouts do not require electricity or maintenance of traffic lights.

Do roundabouts require more space than conventional intersections?

While roundabouts require more space than a four-way stop, they take up about the same or often less space than a signalized intersection, particularly when left- or right-turn lanes are necessary.

How are roundabouts “greener” than multi-stop or signalized intersections?

With multi-stop and signalized intersections, traffic must sit and idle while it waits for its turn to go. With roundabouts, traffic often only needs to slow down and yield, rather than come to a complete stop. The avoided stop-and-go saves fuel, shortens travel times and reduces overall car emissions.

Do roundabouts have less traffic capacity than conventional intersections?

No. The capacity of a signalized intersection is typically much less than a roundabout, and the capacity of an all-way stop is half as much as a roundabout at best.

When might a roundabout not be the bes choice for an intersection?

Roundabouts work best within a range of specific traffic volumes, ratios and patterns. When traffic volumes are too low, vehicles tend to travel at unsafe speeds through roundabouts. If traffic volumes are too high, particularly in one direction, then a signal is often necessary to allow cross traffic to enter the intersection. Finally, if intersections include three or more through lanes of traffic, a roundabout would likely confuse and frustrate many drivers.

How do I correctly navigate a roundabout?

1. As you approach a roundabout, prepare to reduce your speed to 15 to 25 miles per hour. Road design and signage will encourage you and those around you to drive at a slow, uniform speed.
2. As you approach a roundabout, slow down, look left and expect to stop. If there is no traffic in the roundabout or there is a wide enough gap between cars, however, a stop is not required. Most important, remember that you must yield to vehicles already in the roundabout.
3. As you approach a double-lane roundabout, look for lane markings in the road, and choose the appropriate lane depending on where you want to go. Just like at a signalized intersection, don't expect to be able to turn left from a right turn lane.
4. Don't change lanes in a multilane roundabout. If you need to exit and you find yourself in the inside lane, just go around the roundabout again. It will only add a few seconds to your trip.