A design-build project is on track to replace three sets of aging bridges on Interstate 70 in Columbia, Missouri in 14 months.
"The bridges were in need of replacement," says Travis Koestner, Project Director and Assistant District Engineer for the Missouri Department of Transportation's Central District. "The design of the bridges was such that they were difficult to rehab and maintain, so the best option was to get the bridges replaced."
The existing bridges were built in 1957 and are in poor condition. Sixty-five thousand to 80,000 vehicles use that stretch of the interstate daily.
The Addition of Roundabouts
The $18 million Columbia I-70 Bridges Project entails replacing three sets of bridges at Business Loop 70, Garth Avenue and Route 763 Range Line Street. All of the bridges are over traffic, not water. Crews also are building a double roundabout interchange at Range Line and at Business Loop 70 two dual-lane roundabouts on the north and south side of I-70.
MoDOT selected roundabouts as an intersection control device, due to its history of improving safety and traffic flow. Roundabouts can decrease crashes by as much as 75 percent.
"Through traffic modeling, with the amount of intersecting traffic, the roundabouts produce the best level of service," Koestner says. He added that signals require maintenance whereas roundabouts do not require the same level of ongoing service. The roundabouts also allowed the design-build team to eliminate turn lanes, which shortened the bridges.
The City of Columbia already has quite a few multilane roundabouts, so Koestner does not expect any difficulty from the driving public.
Emery Sapp and Sons, a company with its roots in Columbia, received the design-build contract for the project in June 2015. The company's Columbia office is only a few blocks from the project. Josh Doerhoff, Project Manager for Emery Sapp, calls the 14-month schedule aggressive.
"It's a quick turnaround for a job of this size, with this volume of traffic and this many phases," Doerhoff says. "We have a lot of resources we have been able to commit to it. We are able to work in three different locations at any one time. We are working day and night."
The DOT let the job by setting the price and allowing the contractor to decide the scope. MoDOT provided a prioritized list of a number of optional improvements.
"The contractor had to replace the bridges but then we asked what other improvements could you give us," Koestner explains.
Emery Sapp proposed improvements on the interchanges at Business Loop and Range Line. At Business Loop, the team is replacing five signals with a large roundabout on the south side and a smaller roundabout north of the interstate. At Range Line, the team proposed a "dog-bone" configuration with roundabouts north and south of the interstate.
Work commenced before final drawings were done, another thing to speed up construction of the bridges. Koestner praised the partnership.
"We've been open and honest and take issues head on and talk about them," Koestner says. "The team has been good with that."
Maintaining traffic flow was a priority for MoDOT. Emery Sapp has kept I-70 open.
Emery Sapp and design partner Parsons of Chesterfield, Missouri, decided to build the three new bridges, including the steel girders and concrete decks, on new substructures north of the existing bridges, then build substructures for the new bridges and slide them into place.
"That was crucial for us getting the job," Doerhoff recalls. "I think that was a winner in MoDOT's eyes."
Emery Sapp has experience sliding bridges. The company uses a proprietary technique.
The foundations are H-piles with pile caps. MSE walls were placed in front of the piles. The bridges are 85- to 90-feet-long, single spans with weathering steel girders, which made the bridges lighter than concrete to slide into place. Emery Sapp will slide all three into place within a month.
The Business Loop bridge is four-lanes and 90-feet-wide. The others are about 45-feet-wide. The westbound bridge over Range Line will be slid into place on a weekend, with the bridge closed to traffic.
"The winner of the job really excelled at minimizing traffic impact," Koestner reports. "We've gotten lots of positive comments from folks."
At the Business Loop, the road will be closed for 45 days to build the roundabout. During that period, Emery Sapp will work 24 hours per day.
Emery Sapp is building the other roundabouts in a different location than where traffic currently runs. Koestner anticipates a lot of roundabout work will take place when each bridge is closed as Emery Sapp slides the bridges on jacks into place, while maintaining two lanes on I-70.
"This is a great approach for a high-traffic location such as this," Koestner says. "At each location they will be moving a bridge. They are not being done all at once to minimize traffic impacts."
MoDOT also has asked local residents using I-70 like a city street to avoid the interstate and use other options to prevent snarling of cross state traffic. Traffic has increased on city streets. I-70 volume is about 80,000 in Columbia but 35,000 on either side of the city.
Traffic under the bridges has been affected for limited amounts of time. MoDOT has worked with the city of Columbia on signal timing to help ease any congestion.
The "temporary" substructures have been built to hold bridges with traffic loads. They will stay in place and be used for future bridges when funds become available to add capacity to I-70, Koestner says.
"I-70 is in dire need of structure and capacity improvements," Koestner adds. "It was one of the goals to build bridges that were easily expandable."
Work began in August 2015 and is on schedule for completion in October 2016. It's been a safe job, with no serious incidents, Doerhoff says. Emery Sapp worked all winter on the project. Doerhoff is proud the company has hit its targets and remains on schedule.
"We think we got great value with the design-build method of setting the price and having the contractors bid the scope of the job," Koestner says. "That's great value for the taxpayers of Missouri."
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