ST. GEORGE – Commuters can expect to see road work begin on the Exit 8 interchange in St. George around July as the Utah Department of Transportation gives the green light for interchange improvements. If all goes as planned, construction will end early next year and traffic congestion at the interchange will be reduced.
Current projections by UDOT maintain that the interchange will experience “congestion failure” by 2040, so improvements are needed to meet future traffic demands.
During the 2013 Dixie Regional Transportation Expo, Kevin Kitchen, a spokesman for UDOT, said improvements to the Exit 8 interchange are a part of UDOT’s plans to improve traffic flow along Interstate 15 in Washington County. He also said improvements made to the interchange would not only make travel on and off I-15 easier, but would benefit traffic in St. George as well.
Typically during peak travel times in St. George, traffic tends to back up on St. George Boulevard. Proposed improvements to the interchange, such as allowing motorists to make nonstop right-hand turns onto I-15, are projected to enhance traffic flow and help mitigate excessive traffic congestion.
Proposed areas of improvement also include the St. George Boulevard and 1000 East intersection, as well as the River Road intersection.
Diverging diamond interchange and design-build
Kitchen said the general design UDOT is shooting for is a “diverging diamond interchange,” or DDI.
According to UDOT, the DDI “allows for two-phase operation at all signalized intersections within the interchange instead of the six or more found in other interchange designs. This is a significant improvement in safety, since no left turns must clear opposing traffic and all movements are discrete, with most controlled by traffic signals.”
Pedestrian accommodations have also been factored into the design.
A diverging diamond interchange has already been constructed in American Fork. UDOT produced the following video to illustrate how the new interchange works:
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Note: This video details the DDI in American Fork, Utah, not the one to be built in St. George. | Video courtesy of the Utah Department of Transportation
The project is slated to begin in July, Kitchen said, and it would be a “design-build” affair. This means the contractors bidding on the project also propose their own designs for the interchange’s improvements using the diverging diamond interchange as a base.
According to UDOT, the design-build process helps cut down on project delivery time and the overall costs, as one company is handling the majority of the work involved.
During a St. George City Council meeting, UDOT project manager Kim Manwill also said the design-build process “provides innovation from the private sector.”
The running budget for the project is $16 million, Manwill said.
Whichever design-build team is picked will be working with the preexisting infrastructure of the interchange. Any elaborate designs proposed the project will not only add to the price, but add time to the project as well.
UDOT wants the interchange to be completed by spring 2014.
“We want to make this work as efficiently as possible with the dollars available,” said Dana Meier, UDOT planning engineer.
Kitchen said the winning design-build team should be picked sometime in May.
Traffic impact and pre-construction open house
With construction projected to take place sometime in July through to the end of the year, Marc Mortensen, assistant to the city manager of St. George, said UDOT would coordinate with the city on when to halt work for big events that already impact traffic like the St. George Marathon.
A pre-construction open house will also be held sometime in June or July where interested parties can attend to learn more about construction impacts, maintenance of traffic in the area during construction, and tips and suggestions for keeping businesses thriving during construction.
A hotline has also been set up to take questions and suggestions concerning the project. The hotline number is 435-216-9313.
Information can also be obtained on the project’s website.
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