The Missouri Dept. of Transportation had $18 million to replace original voided concrete slab bridges at three locations on Interstate 70 in Columbia. MoDOT got the new bridges—and then some.
“Design-build is an animal unto itself. With the right contractor and right engineer, we can do it well,” says Timothy Broyles, design manager, Parsons Corp., “and this project has been a great success. MoDOT would have never gotten the scope if this wasn’t design-build. Scope was definitely maximized, and design-build helped exceed the expectations.”
As they did in 2001 on the Gasconade River Bridge on I-44 in the southwest region of the state, design lead Parsons and contractor Emery Sapp & Sons teamed up on the current bridge sliding project in Columbia, a busy city of about 120,000 located smack in the middle of the state. The ongoing project marks the first time Emery Sapp has successfully landed a design-build project for MoDOT, but the previous relationship with Parsons under similar construction conditions on I-44 definitely paved the way, says Chip Jones, project manager with Columbia-based Emery Sapp. “We could tell, pretty early on anyway, that there were going to be slides involved with this to minimize traffic disruption.”
On a stretch of Interstate highway that averages 80,000 vehicles per day, “we have had all four lanes moving during daylight hours,” says Jones. “Even during the bridge slides, we maintained four lanes of movement, which was extremely important based on the traffic count. We knew that from MoDOT; it was one of their stressing points in their proposal when we were bidding it.”
The reason is that I-70 through Columbia is as much a local road as it is an Interstate highway. “The team has done a great job of keeping that traffic flow going,” says Travis Koestner, assistant district engineer, MoDOT Central District. “Anytime during the day, traffic can go at least 50 miles per hour on two lanes in each direction, which is pretty critical, because anytime during the day you have less than two lanes in one direction, you back up traffic there. We know that from experience. Pretty well how the team won the job is that they had the fewest impacts to the traveling public while doing the project.”
Replacing the old structures required tricky work, says Jones. “The bridges there were sound structures, but they were worn out. They did their lifetime plus, so they needed to be replaced,” says the contractor. “Part of our proposal and the reason MoDOT did the design-build was to see who could build the better mousetrap for the local traffic underneath.”
The Triple Play
Built in 1957, the three sets of I-70 bridges being replaced are located within a two-mile stretch. “All three bridge slides have had a slightly different component,” says Broyles. “I’m proud of all three locations.”
The first slide occurred at the middle location, where I-70 crosses over Garth Avenue. This, notes Jones, was the cleanest location, since there is no interchange at Garth. The new steel-girder westbound bridge, the one ultimately slid into place, was built first to the north of the highway, to where westbound traffic was shifted temporarily. Eastbound traffic was correspondingly shifted to the original westbound traffic, allowing the new eastbound bridge to be built in place of the original eastbound span and wide enough to temporarily handle all four lanes of traffic when the original westbound bridge was closed and dismantled. The new westbound bridge was then slid into place using hydraulic jacks and about 15 bottles of dishwashing liquid used as a lubricant to help move the 800,000-lb structure along stainless steel plates. “It’s a slow-moving process,” says Jones. “With the first two bridges, we probably averaged 9 feet an hour. We were roughly moving them 36 feet, so about four hours per each slide. They were moving at a snail’s pace.”
The second slide occurred at the easternmost location, at the Rangeline Street interchange, and followed a similar process, but the new eastbound span could not temporarily accommodate four lanes of traffic. To keep their traffic flow promise, Emery Sapp and Parsons utilized the off and on ramp on the highway’s south side as an eastbound through lane during construction, “but you don’t want that in a long-term condition, like we did at Garth,” says Broyles. “So this is where I am actually more proud of Rangeline. We slid that bridge, tied it in and reopened it within 48 hours. That’s the benefit of sliding a bridge.”
As part of “the value-add” to the bridge replacement project, Rangeline at I-70 was transformed into a “dogbone” formation with roundabouts at each end, replacing stoplights that had created a daily congestion issue. “We have maximized the design for traffic, and we have maximized the design for safety,” says Broyles, noting the work on the project of design team partners Lochmueller Group, Civil Design Inc. and Geotechnology Inc. “A roundabout is proven much safer because there are no conflicting movements of traffic.”
The third slide, the biggest one and encompassing the entire width of the highway, is taking place at Business Loop 70 and necessitated a “very aggressive” 45-day closure of the road below, says Broyles. To keep two lanes flowing both ways on I-70, the off and on ramps to the north and south are temporarily in use as highway wrapping around the worksite where the new 90-ft, single-span bridge is slid and tied in at a new location, which in itself requires some additional Interstate construction for new approaches. “From the time we hit the go button of shutting things down and shifting traffic, to the time we slid the bridge was two weeks,” says Broyles, projecting that I-70 traffic itself will be back to normal in less than 30 days total.
At the same time, Business Loop 70 below is being moved to accommodate both the new bridge and roundabouts to the north and south that will, as at Rangeline, better accommodate intersecting traffic. The new off and on ramps will bleed into the roundabouts.
“It’s been interesting and exciting at the same time,” says Jones. “You sit back and watch what our guys and gals can accomplish, it’s pretty phenomenal. That’s the fun part of why I am doing what I do. I could have all the ideas in the world of what I think we can do, but it takes the workers to pull off some of the miracles we have asked for. They’ve risen to the occasion and exceeded expectations in many cases.
“One of our competitors thought we were totally nuts on this 45-day closure, and, knock on wood if everything continues, we’ll complete it in less than 45 days. That makes it exciting,” he adds.
The entire project will be finished by early fall, but the I-70 team has already provided MoDOT with potential opportunities if and when expansion funding becomes available.
“Since we already had temporary structures built to the north, we just made them out of concrete and H-pile structural steel and are leaving them in place,” says Jones. “That gives MoDOT the flexibility to come back at a later date and actually just put a superstructure and deck on it and have a working structure pretty quick and easy.”
Where possible, bridge walls were built to accommodate an additional lane, says Broyles, crediting “the team concept” of design-build project delivery. “For this type of job where there are multiple options and this much traffic to deal with,” agrees Koestner, “we think design-build was the right way to go.”
From the contractor’s side, “it definitely has its place,” says Jones. “It gives the freedom to contractors and engineers to work together, rather than an engineer sitting in an office and trying to guess what a contractor can do.”