How This Mayor Improved Traffic Congestion Problems in His City

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As part of our efforts to promote professional development among city leaders, each week we’ll be featuring a new video focused on cities, community issues or local government. In this week’s edition, Mayor Clint Folsom shares how a revolution in transportation infrastructure, a diverging-diamond interchange, reduced traffic and accidents along a busy highway in Colorado.

Have a similar big idea to share? We are currently accepting speaker submissions for the 2016 Big Ideas for Small Cities event to be held at the City Summit in Pittsburgh, Pennsylvania, November 16-19, 2016.

Superior, Colorado, Mayor Clint Folsom talks about an innovative new highway interchange design known as a diverging diamond interchange, which saves time and money in construction, uses less land, and improves the flow of traffic.

What are the goals?

The existing interchange at McCaslin Boulevard and US Route 36, which lies between the Colorado towns of Superior and Louisville, cannot accommodate the increasing traffic of the growing Denver suburbs. Faced with budget cuts and limited options, rebuilding the intersection was not an option. The chosen solution: retrofitting the existing overpass into a diverging diamond interchange.

The new interchange alleviates congestion by temporarily crossing the parallel directions of traffic on the overpass as the span traverses the interstate and then allowing the traffic to return to its appropriate side after exiting the overpass. Such a system eliminates the need for left-hand turns that cross the flow of traffic; a major cause of both congestion and accidents. Additionally, the design uses less land by eliminating the need for special turning lanes, allowing for expanded space for pedestrians and traffic flow.

How is the project being executed?

The cities of Superior and Louisville, Colorado initially conducted studies to find a solution to the McCaslin bridge bottleneck that separated the two communities. Both cities joined forces with Colorado Department of Transportation and the Denver Regional Transportation District (RTD) to finance the $12.5 million project. Superior is financing the largest share of the project with a $5 million municipal contribution. The project avoided high costs, by preserving and repurposing the existing infrastructure.

Additional Features

In addition to improving traffic flow, Colorado’s newest DDI will have several other features to alleviate traffic congestion and improve safety. A series of bike paths and shortened crosswalk crossings will lower the risk of accidents involving pedestrian. A new RDT stop, the Denver Metropolitan Area’s bus service, will avoid the interchange all together through the use of special ramps, saving commuters an average of 3 minutes each way.

Route 36 Commuting Solutions

Presented at the 2015 NLC Congress of Cities
Mayor Clint Folsom, Superior, Colorado –
NLC contact: Brooks Rainwater, Director, City Solutions and Applied Research, National League of Cities –

Paul Konz headshotAbout the Author: Paul Konz is the Senior Editor at the National League of Cities.