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I-170 & Olive Blvd. Interchange Project -- Project Accelerated!

A project to improve the I-170 & Olive Boulevard interchange by relocating the interchange, widening the ramps to and from the interstate, and widening Olive under I-170.

What Is Happening Now?

  • Most of the work on the roadway of Olive and I-170 has been completed. Crews will be installing sidewalks and completing some grading work.
  • MoDOT held a ribbon cutton on Olive Blvd. Dec. 7.
  • This project was awarded to Millstone Bangert, Inc. for $25.9 million.


What Were The Problems With The I-170 & Olive Boulevard Interchange?

The I-170/Olive Boulevard interchange was very congested due to several factors. Traffic exiting from I-170 onto Olive Boulevard routinely backs up onto the ramps due to the fact that the ramps from I-170 onto westbound Olive Boulevard are only one lane and provide only one lane for turning. Traffic on Olive Boulevard entering I-170 backs up into the thru-lanes on Olive Boulevard. Also, the I-170 exit and entrance lanes at Olive Boulevard are not long enough for traffic to safely and efficiently exit and enter the interstate. More than 100,000 vehicles a day travel on northbound and southbound I-170 at this location.

What Was The Proposed Solutions?

MoDOT constructed the interchange as a single point interchange and moved it slightly to the west. A single point interchange can move large amounts of traffic through a small amount of space and is controlled by one set of traffic signals located at a single point at the center of the interchange. The signals direct through-traffic, as well as all traffic that must turn left to enter or leave the highway.

Other steps to help alleviate congestion at the interchange included constructing two-lane ramps from northbound and southbound I-170 onto westbound Olive Boulevard and constructing a two-lane ramp from eastbound Olive Boulevard onto northbound I-170. Olive Boulevard was widened from five to six lanes at the I-170 interchange to accommodate a second turn lane from eastbound Olive Boulevard to northbound I-170. A third lane was also be added to westbound Olive between I-170 and Dielman Industrial Ct. MoDOT also lengthened the I-170 exit and entrance lanes at Olive Boulevard so that traffic can safely and efficiently exit and enter the interstate.

Why will the I-170/Olive and New I-64 project be under way at the same time?

The money for the I-170 project is available now and has been committed to this project for many years. In fact, this project was planned and the funding was committed well before MoDOT knew that funding would become available for the New I-64 project. The funding would have been lost if not used. MoDOT’s contractor has made a proposal to accelerate the contract and complete the work by the end of 2007.  This will require the closure of ramps during different stages of construction. For more information on the New I-64 project, please visit the web site.

Is this project over budget?

We awarded the contract for this project by spelling out the specific requirements for the job (to include when we needed it done, to what standards, and how we needed traffic moved) and then awarding the contract to the lowest bidder. This contract was awarded for about $26 million. The contract is what we used to determine budget – we are right on budget and ahead of schedule.

Why was the project let for $7 million more than its projected cost of $20 million?

When we sent originally planned this project, our estimated costs were about $20 million (in 2005 dollars). The final project cost was higher because:

  • Last year, we had a banner year – the biggest year overall – in construction work.
  • We had a tight time frame to complete this project – it needs to be done before significant work starts on the new I-64 rebuild.
  • And, the cost of raw materials increased as did the price of gas.

So, because of the increase in costs, the large amount of construction work and the need to complete this quickly, our bids were higher. Our contractors had to pay for hiring additional labor and potential overtime to complete the job on time.

  • We also included a design expansion for a pedestrian and bike trail enhancement.  This cost of this $650,000 enhancement will be returned to MoDOT by the Great Rivers Greenway District.

Do we need this project?

Absolutely! This is a vital project for economic growth in Olivette and University City. The voting body of the East-West Gateway Council of Governments recognized that and made this project a regional priority. This intersection was exceptionally congested – this project will reduce that congestion.

Current Project Timeline:

Late 2007
Project accelerated -- construction complete.

Project Cost:
$25.9 million.

Project Map
View the I-170 and Olive Blvd. project map.

Sign up for e-updates

MoDOT wants to ensure all stakeholders stay updated and informed about the project during construction. We will send out periodic "e-updates" via e-mail when they become available. If you would like to be added to this list, please send an e-mail to Drew Gates at Andrew.Gates@modot.mo.gov. If you do not have access to e-mail, you can call MoDOT toll-free at 1-888-ASK MODOT (275-6636) for updates on the project.

For more information:
Please e-mail MoDOT Project Manager Tom Montes de Oca or call 888-ASK-MODOT (275-6636).

Please e-mail MoDOT Area Engineer Karen Yeomans or call 888-ASK-MODOT (275-6636).

Updated January 30, 2008

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