Cover image source: Torey Nelson - Skagit County Public Works

Circulatory

roadway

Counterclockwise

circulation

Accessible

pedestrian crossing

Splitter Apron

island

Pavement

Markings at Entry

Landscape

buffer

Bicycle lane

treatment

Central

island

Sidewalk or

shared use

path

Figure 1. Modern Roundabout Schematic

What is a Roundabout?

A roundabout is a type of circular intersection, but is 

quite unlike a neighborhood traffic circle or large rotary. 

Roundabouts have been proven safer and more efficient 

than other types of circular intersections.

Roundabouts have certain essential distinguishing features: 

y Counterclockwise Flow. Traffic travels

counterclockwise around a center island.

y Entry Yield Control. Vehicles entering the roundabout

yield to traffic already circulating.

y Low Speed. Curvature that results in lower vehicle 

speeds throughout the roundabout.

FHWA identified roundabouts as a Proven Safety 

Countermeasure because of their ability to substantially 

reduce the types of crashes that result in injury or loss 

of life. Roundabouts are designed to improve safety for 

all users, including pedestrians and bicycles. They also 

provide significant operational benefits compared to 

conventional intersections.

ROUNDABOUTS

& Tribal Governments

For More Information

Jeffrey Shaw, P.E., PTOE, PTP

FHWA Office of Safety

2 0 2 . 7 3 8 . 7 7 9 3 or jeffrey.shaw@dot.gov

Hillary Isebrands, P.E., PhD

FHWA Resource Center

7 2 0 . 5 45.43 67 or hillary.isebrands@dot.gov

Adam Larsen

FHWA Tribal Transportation Program

3 6 0 . 619.7 7 51 or adam.larsen@dot.gov

To learn more about roundabouts, please visit: 

safety.fhwa.dot.gov

Publication number FHWA-SA-14-096 UPDATED jULY 2020

Partnering on Roundabouts

Successfully delivering a roundabout project requires 

coordination with all stakeholders. This naturally 

includes the road authorities involved, but efforts 

should also be made to seek input from other public 

safety providers (i.e., police, fire, EMS) and members of 

the community. Open communication can help clarify 

goals and expectations, and provide feedback that 

shapes the roundabout design for the better, ultimately 

ensuring that the final project can appropriately serve 

its users – from large trucks moving freight to children 

walking to school.

Like any intersection, a roundabout can sometimes be 

jointly owned by multiple units of government, such 

as a tribe and county. This makes building partnerships 

between all stakeholders a necessity. However, it also 

presents opportunities to pool and leverage resources, 

share costs, and ultimately lead to a project becoming 

a reality sooner than would otherwise be possible. 

The cost to construct a roundabout varies based on 

many factors, but is often a cost beneficial alternative 

to traffic signals.
Source: Google Earth Pro

Roundabout Highlights Tulalip Testimonial

In 2001, the Tulalip Tribes constructed a roundabout at 

the entrance of their newly developed Tulalip Resort 

Casino in Washington State. For the intersection of 

34th Avenue NE and Quil Ceda Boulevard, the Tribes 

chose a roundabout over a traffic signal because of 

the immediate safety and mobility benefits, as well as 

lower future maintenance costs. 

Though initially hesitant, as they learned more the 

Tribes realized roundabouts provided more advantages. 

The roundabout was landscaped with features that 

reflected tribal heritage using colors, materials and 

other elements. The roundabout now serves as the 

grand entrance to the development.

For the Tulalip Tribes, the roundabout is a safer,

cost-effective, more visually appealing alternative

to a traffic signal.

For more information, please contact:

Debra Bray

Economic Development Project Manager

Tulalip Tribes

dbray@tulaliptribes-nsn.gov.

The Benefits of Roundabouts

Roundabouts can provide lasting benefits and value 

to tribal communities in many ways.

y Roundabouts improve safety. They slow vehicle 

speeds to a range of 15-25 mph, and reduce the 

number of severe crashes by 78-82%.1

y Roundabouts enhance traffic flow. 

Roundabouts do not have the same stop-and-go 

conditions as traditional intersections. This allows

for a smoother, more efficient flow of traffic.

y Roundabouts have lower lifecycle costs. They 

eliminate the equipment, maintenance, and 

electrical costs necessary for traffic signals.

y Roundabouts provide opportunities for 

aesthetic or cultural enhancements. The center

island at a roundabout can incorporate features 

and landscaping that highlight tribal heritage. 

There are many examples of roundabouts from 

around the United States with thoughtful and 

appropriate center island treatments.

y Roundabouts offer benefits to pedestrians 

and bicyclists. Low vehicle speeds at 

roundabouts mean reduced risk for people 

walking and biking. Crosswalks are set back from 

the circle, have shorter crossing distances, and 

involve only one direction of traffic at a time – 

making crossings simpler for both pedestrians 

and drivers. Bicyclists can choose to ride through 

a roundabout at a comfortable speed consistent 

with traffic or to follow shared use paths when 

provided. 

1 AASHTO, Highway Safety Manual (Washington, DC: 

AASTHO, 2010)

Indian Route 15 at U.S. 191/AZ 264

Location: Ganado, AZ

Tribe: Navajo Nation

Noteworthy Attributes:

yFeatures a design pattern that 

reflects Navajo Nation heritage

yAlong a high-speed rural highway 

with high school in SW corner

Wisconsin State Route 172

Location: Oneida, WI

Tribe: Oneida of Wisconsin

Noteworthy Attributes:

yTribal identity reflected in center 

island turtle-shaped landscaping

yFunctions as main entrance to 

regional airport and tribal casino

Source: Google Earth Pro

Source: Google Earth Pro

Haxton Way at Kwina Road

Location: Bellingham, WA

Tribe: Lummi Nation

Noteworthy Attributes:

y Oval layout with

hardscaped center island

including totem features

and native language

 Source: Kirk Vinish – Lummi Nation

Source: Google Earth Pro

Source: Brown County