Jan 4, 2023 - News

Des Moines' 'road diet' results in surprisingly faster speeds

A photo of Douglas Avenue in Des Moines.

A roughly two-mile stretch of Douglas Avenue in DSM was in 2021 converted from four lanes to two travel lanes and a turn lane as part of an ongoing safety improvement pilot project. Photo: Matthew Miller/Iowa Department of Transportation

Drivers are going faster along a portion of Douglas Avenue in Des Moines where a lane was removed in 2021 as part of a safety improvement pilot project to help calm traffic, according to city data obtained by Axios.

Why it matters: The unexpected result will factor into whether or how the lane reduction becomes permanent.

Catch up fast: The reduction came between Merle Hay and Lower Beaver roads in July 2021.

  • The move followed input from a coalition of area citizens and business leaders concerned with the corridor's high rate of crashes.
  • Douglas Avenue is a part of U.S. Highway 6 and the lane reduction required the approval of the Iowa Department of Transportation.

Context: DSM began a series of 'road diet' projects along busy streets about three years ago.

  • Reducing the number of lanes and adding amenities like bike lanes are intended to slow traffic and boost a community's overall livability.
  • Portions of East Euclid, University and Sixth avenues are among the areas that have been affected.

By the numbers: Average speeds are as much as 5 miles per hour faster since the lanes were reduced, city engineer Steven Naber told Axios.

  • The increase is believed to be linked with a trend of escalating driver speeds across the state, Naber said.

Yes, but: Despite higher speeds, crashes have decreased about 10% throughout the corridor — from an average of 82 a year between 2016 and 2020 to 74 last year.

  • A designated turn lane created as part of the pilot project helps avoid sudden stops in traveling lanes and reduces crashes, Naber said.

The 0ther side: The city's road diets have been met with mixed responses from residents, Naber said.

Meanwhile, last month, the DSM City Council authorized city staff to apply for grants that would make the Douglas Avenue changes permanent should the pilot project be deemed a success.

  • The road and its curbs along the roughly two-mile stretch would be replaced under a $10 million project that could begin in 2026.

🗣 Got feedback? Des Moines' Traffic and Transportation division can be reached at 515-283-4973 or via email at [email protected].


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