Road diet? Diets aren't just for people anymore

Posted in: Bridges, Highways

As many of us go on a diet for our New Year’s resolution, it is a good time to review our transportation needs and determine if certain roadways should go on a diet as well. Road diets are becoming increasingly popular as transportation agencies seek to provide multi-modal transportation accommodations within existing right-of-way.

The primary benefit of a road diet is to provide pedestrian and bicycle accommodations within the original roadway footprint or existing right-of-way. Typically, road diets restripe or reconstruct a four-lane undivided roadway into a three-lane roadway to provide two through lanes and one center two-way left-turn lane. Other accommodations may include transit stops, on-street parking, pedestrian refuge islands or wider lanes.

Before and After
Before and after images show a conversion of an undivided four-lane roadway to a three-lane undivided roadway with two through lanes and a center two-way left-turn lane. (Courtesy of Virginia Department of Transportation) – FHWA Stewardship Newsletter, November 2014.

Like New Year’s diets, roadway diets are not a good fit for everyone or every situation. A number of factors must be reviewed prior to placing a roadway on a diet, including:

  • Traffic operations
    • Travel times
    • Intersection delays
    • Redirection to other roadways
    • Side Road Operations
    • Speeds
  • Safety
  • Multimodal operations including pedestrians and bicyclists
  • Access Management
  • Cross-Section Elements

Luckily, there is a wealth of information available from the Federal Highway Administration to provide engineers and transportation agencies with information about road diets, including the benefits and factors to help determine whether a road diet is the right solution for a particular roadway. Currently, FHWA is reviewing road diets as part of the Everyday Counts 3 initiative across the country. According to the EDC initiative, FHWA works with State departments of transportation, local governments, tribes, contractors, universities, industry groups and other stakeholders to identify a new collection of innovations to champion every two years. The innovations all share common goals:

  • Shorten project delivery
  • Enhance the safety and durability of bridges and roadways
  • Reduce traffic congestion
  • Protect the environment

As road diets become a more viable solution for roadway needs, more information has become readily available for roadway engineers. The FHWA website provides information on road diets under the EDC-3 Initiative. The recent FHWA Stewardship Newsletter also includes information concerning road diets. The Kentucky Transportation Center has completed a research document for the Kentucky Transportation Cabinet that provides Guidelines for Road Diet Conversions.

With a wealth of information available, we can confidently evaluate roadways to determine if a road diet is the correct solution for a particular roadway. Happy dieting!

John Rathke, PE, SE

About the Author

For John Rathke, P.E., S.E., it is more than managing more than 30 highway and bridge projects each year. It is about connecting with clients and listening to what is important. A leader in transportation engineering, John says that for him, the greatest reward is seeing the constructed product and sharing the pride and accomplishment with his clients, team and the public. According to John, “It’s all about teamwork.”

Read more posts by John Rathke, PE, SE

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