Converting Four-Lane Undivided Roads to Three Lanes: A Low Cost Safety Improvement


Dates and Locations

March 21, 2017
Kirkwood Community College
Iowa Hall Room 316A
6301 Kirkwood Boulevard Southwest
Cedar Rapids, IA 52404

March 22, 2017
Raccoon River Park – Nature Lodge
2500 Grand Avenue
West Des Moines, IA 50265

March 23, 2017
Kings Pointe Waterpark Resort
1520 East Lakeshore Drive
Storm Lake, IA 50588

Registration at 8:15 a.m./Event starts at 8:30 a.m.


There is no cost for this event. Lunch will be provided.

Online Registration

Registration for this event is all online and is available at the following links:


Please register for this event by March 14, 2017.


Undivided roadways often experience a large number of crashes – especially between high-speed through traffic, left-turning vehicles, and other road users. One treatment for addressing this safety concern along four-lane undivided roadways is to convert the cross section to three-lanes (one type of Road Diet). This type of conversion typically involves removing or narrowing motor vehicle lanes and utilizing the space for other uses, including but not limited to a two-way left-turn lane (TWLTL), non-motorized travel modes, or parking.

FHWA, in cooperation with the Iowa DOT, is pleased to offer a one-day workshop on this low-cost, proven safety countermeasure that explores how agencies can convert four-lane undivided roadways to three lanes to improve safety, operations, and livability in their communities.

Participants will be introduced to the FHWA Road Diet Informational Guide and guided through a decision-making process to determine when this type of conversion may be a good solution.

Who Should Attend?

  • Transportation engineers and planners
  • Pedestrian & bicycle and Safe Routes to School program coordinators
  • Local police, fire, EMS and transit personnel
  • Community leaders

Workshop Learning Outcomes

  • Learn about the different types of Road Diets and why they work.
  • Understand the characteristics that make these type of conversions the right choice.
  • Identify roads that are good candidates for cross section conversion.
  • Learn what segment and intersection design elements are affected by cross section reconfigurations.
  • Practice reallocating street space for other uses, including non-motorized user needs.

Tentative Agenda

8:15 a.m. Registration
  Introduction and Overview
Determining Feasibility
Design Considerations
Determining Effectiveness
Case Study Exercise(s)
4:00 PM Adjourn
  Lunch will be provided at approximately 12:00 p.m.

For More Information

If you have any questions or need more information, please contact Keith Knapp at 515-294-8817 or

Publish On: 
Friday, February 17, 2017 - 13:15