I-270 and Dorsett Interchange Project


Dorsett Road looking west towards Interstate 270		Interstate 270 looking northbound at Page Avenue/Route 364

What are the problems with the I-270 and Dorsett interchange presently?

The Interstate 270 and Dorsett interchange is congested due to heavy traffic utilizing the interchange.

What Is The Problem With The Existing Northbound Interstate 270 Ramp To Westbound Route 364?

The existing loop ramp from northbound Interstate 270 to westbound Route 364 is not designed to handle current traffic volumes, which results in daily congestion. In fall 2003, approximately 3,200 vehicles were using this ramp. In fall 2004, more than 11,000 vehicles were using this ramp. There are also conflicts between vehicles merging onto westbound Route 364 and vehicles merging onto the ramp to southbound Interstate 270. This creates a "weaving movement" and contributes to congestion.

What’s the Latest on the Northbound Interstate 270 Ramp to Westbound Route 364?

Construction could begin on the project as early as August 2009 with no traffic impacts due to the I-64 closure and reconstruction.

What's the latest on the I-270 and Dorsett project?

The Missouri Department of Transportation held a public meeting Wednesday, October 24, 2007 on the proposed I-270 and Dorsett Road interchange project. MoDOT experts discussed planned interchange improvements for I-270 and Dorsett and what the local community and motorists can expect. Residents also shared their opinions and provided input on two proposed design options for the interchange.

What is the proposed solution?

I-270 and Dorsett

After presenting two alternatives at the public meeting, MoDOT is proposing to construct the interchange as a diverging diamond interchange (DDI). Some of the advantages of a diverging diamond interchange include free turns for motorists, meaning vehicles don’t cross opposing traffic. Traffic models indicate this type of interchange works well with areas of heavy traffic, such as Dorsett Road.

The city of Maryland Heights will also be relocating Old Dorsett Road and Progress Parkway while this project is under construction.

The diverging diamond interchange is a new type of traffic solution, meeting the needs of intersection safety, increasing capacity and decreasing congestion. The U.S. Department of Transportation Federal Highway Administration has more information about diverging diamond interchanges at the web site below.

http://www.tfhrc.gov/safety/pubs/07048/index.htm

The Missouri Department of Transportation has plans to build three DDI's. The first to open will be at Interstate 44 and Route 13 in Springfield. It will be the first DDI built in the United States. The interchange of Interstate 435 and Front Street in Kansas City was the first DDI approved by MoDOT, but won't be built for several years.

I-270 and Page

MoDOT will construct a new two-lane flyover ramp from northbound Interstate 270 to westbound Route 364. A new auxiliary lane will also be extended on northbound Interstate 270 between Olive Boulevard and Route 364.

In order to allow room for the new northbound Interstate 270 ramp to westbound Route 364, four of the ramps at the interchange will also be rebuilt. The ramps include the westbound Route 364 ramp to southbound Interstate 270, the ramp from eastbound Route 364 to northbound Interstate 270, the ramp from northbound Interstate 270 to eastbound Route 364 and the ramp from southbound Interstate 270 to westbound Route 364. The ramps will be built as they are now.

View a map showing the proposed improvements. (2.47 mb, 1 page)

The documents are provided in Acrobat Reader format. Free Acrobat Reader download

Will these projects close lanes of I-270 during construction?

One single lane of northbound and southbound I-270 could be closed for a short duration during construction. Work will not begin on the project until the I-64 re-construction project is completed.

How much will the I-270 and Dorsett construction cost?

MoDOT is contributing $10 million towards the $30 million dollar cost for this project. Other contributors include the city of Maryland Heights, St. Louis County and federal funds. MoDOT’s portion of funding comes from an economic development fund earmarked especially for roadway improvements linked to community economic development. In this case, Edward Jones is pledging the addition of 500 new jobs.