Expert-on-Hand 

U.S. Department of Transportation 

Federal Highway Administration 

Location 

State of Iowa 

(Central United States) 

Implementation Stage 

🗸 Planning 

🗸 Design 

🗸 Construction 

🗸 Launch 

🗸 Post-Implementation 

Roundabout Type/Setting 

Single- and multi-lane roundabouts 

in urban and rural settings 

Target Audience 

🗸 Engineers 

🗸 Elected Officials/Managers 

Strategies Employed 

🗸 Expert-on-hand 

🗸 Website 

🗸 Managed mailing list 

Iowa DOT Provides “Expert-on-Hand” 

Technical Assistance to Promote 

Roundabouts Across the State 

Background 

Small localities in Iowa, as in other states, do not necessarily have the resources to 

staff a full-time traffic engineer dedicated to analysis and design of intersection safety 

enhancement projects, including roundabouts. The Iowa Department of Transportation 

(DOT) created an innovative program—the Traffic Engineering Assistance Program 

(TEAP)—to deliver this very service to help smaller jurisdictions by providing an “experton-hand,” who visits the jurisdiction, gathers input from local stakeholders, and makes 

recommendations to help the agency identify, analyze, and implement traffic safety 

improvements. In 2004, Iowa DOT expanded its expert-on-hand repertoire to include 

roundabout analysis, design, and outreach support. They implemented this expansion 

in response to frequent questions about roundabout feasibility, how to design a 

roundabout effectively, and how to generate support from the local community. 

Approach 

The TEAP provides a variety of traffic safety engineering consulting services, including 

identifying and recommending intersection improvements based on traffic and 

safety data, dealing with unwarranted traffic control devices, and accommodating 

pedestrians and bicyclists. Through this program, Iowa DOT also offers no-cost, expertlevel roundabout design reviews to any local road agency that needs related technical 

assistance during any stage of the project delivery process. The program provides up to 

100 hours of consulting time to qualifying local agencies with no local match required. 

Iowa DOT also provides an educational component led by an Iowa DOT traffic safety 

engineer, who is available to work with local agencies to help generate stakeholder 

support for roundabouts from, for example, the general public, local businesses, and 

elected officials. The traffic safety engineer can attend local community meetings with 

the general public and/or elected officials as requested. 

In 2008, Iowa DOT held two one-day conferences for local engineering staff that 

brought together engineers and county staff from across the State to provide an 

FHWA-SA-11-029 Figure 1: Screenshot of the Iowa DOT roundabout information website. 

Revised July 2020
 

 

 

 

 

 

Before 

introduction to roundabouts, including an overview of outreach techniques that 

have been successfully implemented, both in Iowa and elsewhere in the United 

States. Experts from across the country, including representatives from regions that 

have successfully implemented roundabouts such as the City of Clearwater (Florida), 

Washington State DOT, and Kansas DOT, discussed their agencies’ experiences with 

roundabouts, what worked well, challenges that they faced, and lessons learned. After 

Figure 3: Before and After – County-led project with 

assistance provided through Iowa DOT’s expert roundabout 

review program. Black Hawk County, Iowa. 

Images Courtesy of Iowa DOT 

Roundabouts Single-lane Roundabout (see diagram below) 

Roundabouts are intersections that Motorists direct traffic in a counterclockwise direc- 1 Approach: Slow down to the osted advisory s eed. 

15 

MPH 

tion around a center island. They have Yield to edestrians in the crosswalk. They have the 

no sto signs or traffic signals. Yield right-of-way. 

signs, directional signs and avement 2 Enter: As you a roach the yield line markings (shark’s 

markings guide traffic through the inter- teeth), yield to vehicles in the roundabout. Wait for a 

section. Traffic generally continues to ga in traffic, then merge into traffic in the roundabout 

move, but at a slower s eed that reduces in a counterclockwise direction. 

traffic backu encountered at traditional 3 Proceed: Continue through the roundabout until you 

intersections controlled by sto signs or reach your street. Avoid sto ing in the roundabout. 

traffic signal lights. 4 Exit: Signal, then exit the roundabout to your right. 

Roundabouts are generally safer Yield to edestrians in the crosswalk. 

than other intersections because they 

tend to reduce head-on, right angle and 

left-turning traffic crashes. They encour- Pedestrians (see diagram below) 

1 

2 

Approach: At the edestrian crosswalk, look left. age slower s eeds and eliminate left turns across traffic. Cross: Cross to the raised s litter island. Look right. Roundabouts can im rove edestrian safety by offering a Finish crossing to the o osite sidewalk. short crossing of one-way traffic moving at slow s eeds. 

Cyclists Generally, cyclists 

should walk their bicycles 

across the edestrian 

crosswalk using the same 

rules as edestrians. 

Ex erienced cyclists 

may navigate roundabouts 

like motorists. Do not hug 

the curb. Bicyclists using 

the roundabout should follow the same rules as motorists. Ride in the middle of 

the lane to revent vehicles 

from assing. Yield to edestrians in crosswalks. 

Truck apron

YIELD YIELD

YIELD YIELD 

YIELD YIELD 

YIELD YIELD 

2

Truck apron: 

accommodat s th r ar 

wh ls of long v hicl s 

A

B

C

D

A

B

C

D

Yield line markings 

Center island 

Raised splitter island 

Crosswalk 

Approaching v hicl s 

must yi ld to p d strians 

in th crosswalk and to 

traffic in th roundabout. 1

2

4 3

1

N v r walk across th 

circulating lan (s) in a 

roundabout to th 

c nt r island. 

This diagram of a single-lane roundabout is an example only 

and does not represent all roundabout designs. 

40 3. Safe Driving Tips 

Figure 4: A page from the Iowa Driver’s License Manual 

illustrates how to use a single lane roundabout. 

Learn More 

Tim Simodynes, PE 

Traffic Safety Engineer 

Iowa Department of Transportation 

515.239.1349

tim.simodynes@dot.iowa.gov

Jeffrey Shaw 

Intersections Program Manager 

FHWA Office of Safety 

202.738.7793

jeffrey.shaw@dot.gov 

The Iowa DOT also manages a traffic and safety e-mail list with over 300 subscribers 

(including university staff, DOT staff, local consultants, and city/county engineering and 

public works staff), enabling wide, but targeted, distribution of important roundaboutrelated messages with the click of a button. 

Results 

Iowa DOT staff believe that 

this program has worked 

well, pointing to the various 

successful roundabout 

projects and programs around 

the State. According to Tim 

Simodynes, traffic safety 

engineer with Iowa DOT, “If a 

city is interested in considering 

a roundabout, they usually 

have questions. Having 

experts available to answer 

those questions correctly is 

what makes the roundabout 

outreach a success. The 

TEAP helps us to do that for 

jurisdictions of all sizes.” 

Figure 2: Screenshot of the Iowa DOT TEAP website.

Because of TEAP, the local municipalities and engineers have changed their perception 

of roundabouts. “If they are open-minded and you give them the facts, they are usually 

sold on roundabouts. Naturally...a first reaction is that a roundabout is a bad idea, but 

it just takes education,” said Mr. Simodynes. 

Lessons Learned 

In addition to bringing a traffc safety engineer to a public meeting, it can be helpful to 

show examples of successful roundabout implementations from other comparable regions 

of the country and provide contact information for those jurisdictions. 

Outreach Investment 

Iowa DOT considers TEAP to be a very cost-effective choice, because the program 

costs are primarily for the program engineer’s salary and/or consultant time, relative to 

the safety benefits that jurisdictions of all sizes reap with the technical and outreach 

assistance delivered through the program. 

Related Products 

Websites 

Iowa Goes Roundabout website 

https://iowadot.gov/traffic/roundabouts 

Traffic Engineering Assistance Program website 

https://iowadot.gov/traffic/traffic-and-safety-programs/traffic-engineering-assistanceprogram-teap