↵ Back: A Placemaker's Primer on Road Diets

This cost-effective, four-to-three-lane road re-striping project in Des Moines, IA, resulted in a safer, multimodal corridor, while catalyzing significant redevelopment.

The Highlights

• Crashes reduced by 50%
• Injury crashes reduced by 30%
• Average speeds reduced by 10%
• 200+ bikers on the road daily
• 50 on-street parking spots added
• Bike lanes implemented
• Private re-investment is taking place in the corridor

The Details

Ingersoll Avenue is located in an established business district that was trying to reinvent itself. The corridor functions as a central business district corridor, and it is a significant bus and commuter route for the city of Des Moines. Comprised of four lanes, the corridor had struggled with pedestrian and bike safety due to high vehicle speeds. Because of its four-lane, undivided layout, Ingersoll Ave also suffered from issues with impaired visibility that caused turning and crossing conflicts and with inadequate parking. Yet in 2004, the City commissioned a study to revisit the traffic flow along Ingersoll Ave, which found that the existing plan for a “unified, pedestrian-friendly street” would not be able to handle the peak traffic levels, meaning that Ingersoll Ave was to remain unchanged.  

From 2006 to 2008, the city recorded 152 total crashes on the corridor—106 of which could be corrected by implementing two-way left turn lanes. So in 2009, the city directed its staff to review Ingersoll Avenue’s traffic and parking conditions again. The new study found that the conversion of Ingersoll Ave. to a three-lane corridor was feasible. In 2009, the city council approved a six-month trial period for the conversion to collect public feedback with a before-and-after evaluation. Before the changes, business owners were evenly split between those who thought the changes would hurt their business and those that thought business would increase.

In 2010, the plans to temporarily re-stripe Ingersoll Ave to a 3-lane corridor were implemented by City crews. Because no curbs needed to be changed, the project was relatively low in cost, and it was implemented through pavement marking only. The city also identified and added 50 new on-street parking spaces. After the re-striping, while speeds along the corridor decreased by an average rate of 10%, no major congestion, delays, diversions, or crashes were observed.

After the trial period, the public evaluation of the changes indicated that the majority of users favored keeping the changes, and perceived Ingersoll Ave to be a safer corridor for both biking and walking. The majority of business owners reported they saw no effect as a result of the changes, but 23% of business owners reported an increase in shopping along the corridor.

The Ingersoll road diet case study demonstrates the value of incorporating feedback from a variety of users and before-and-after evaluations of the proposed changes. The city learned some important lessons from this project, particularly regarding cultivating public support. Many businesses didn’t know what was being proposed, and so the narrative was misconstrued as “bike lanes vs businesses.” The city took note of the importance of providing clear information in cultivating public support for projects such as this.

In 2012, the city created the Ingersoll and Grand Revitalization Plan, expanding the Self-Supported Municipal Improvement District (SSMID) for the area. Within the past several years, the corridor has seen significant redevelopment, including many renovations and the siting of a $15 million grocery store.

Word on the Street

“Ingersoll is the logical bicycle link between the downtown and west side neighborhoods and regional trails.” 
— Ingersoll Ave Study, City of Des Moines

“This project is a great example of successful ‘complete streets’ conversion project.”
— Mike Spack (MikeOnTraffic.com)