A.M. Cohron & Son Reconstruct US 166 Bridge for Improved Safety
A More Comfortable Crossing: A.M. Cohron & Son and Kansas DOT Partner to Update the US 166 Bridge
A new bridge crossing the Arkansas River will create a wider structure for the thousands of motorists and truckers who use Route U.S. 166 daily.
“Loads wanting to come through have progressively gotten bigger and bigger,” says Area Engineer A.J. Wilson, with the Kansas Department of Transportation (KDOT).
The original bridge west of Arkansas City, built in 1937, had one lane in each direction. The entire bridge was 24 feet wide. The new steel-beam bridge will be 44 feet wide, still one lane in each direction but with ample shoulders. About 3,000 vehicles travel on the bridge daily, including about 300 large trucks.
“People told us they were getting more and more nervous driving on that bridge, especially when a big load was coming at you,” Wilson says. He expects the new bridge will give drivers a “good level of comfort.”
KDOT designed the 980-foot-long bridge internally, led by Stephen Bass and Mark Hurt.
Starting Construction and Drilling Shafts
A.M. Cohron & Son of Atlantic, Iowa, received the $6.4 million contract in October 2018. Arch Cohron founded A.M. Cohron in 1928, building maintenance garages for the Iowa Highway Commission. He completed his first bridge project in 1930. The company remains family owned and operated and specializes in bridge construction. It has 17 crews working in the Midwest. A.M. Cohron operates in Iowa, Kansas, Nebraska, and Missouri, but it has worked in several other states. It also has an office in Emporia, Kansas.
“We have great people both in the offices and field that make it happen and will continue to repair/replace structures all over the Midwest,” says Jesse Harlan, Vice President of A.M. Cohron.
Crews could not access the river from April 1 to August 31, due to minnows’ spawning season. A.M. Cohron first created a sand causeway to build the new bridge, because the river was low enough not to need barges for a marine operation.
“We mobilized equipment and multiple crews to the site by December 2018, to begin work,” which started in January, reports Harlan. “During that phase, the crews faced numerous times of high water that not only made river work impossible but washed large portions of the access road away, thus having to re-build it. However, we had multiple very experienced crews and subcontractors on site that made it happen.”
The first step was demolishing the old 945-foot by 24-foot bridge, as the new one was to be built in its place. The location of a city dike precluded building a new bridge next to the old one. KDOT diverted traffic to a detour, which added 30 minutes to a driver’s travel time. The detour took drivers on state roads, not local, residential streets.
Crews slowly and carefully dismantled the old bridge piece by piece, with no explosions.
“The contractor wanted to get out of the river as fast as he could,” Wilson explained.
Twenty-seven drilled shafts, three per pier for nine piers, support the bridge. The deepest reached 51 feet. Subcontractor Mid-West Foundations of Topeka, Kansas, drilled the shafts and A.M. Cohron poured the concrete. All 27 shafts tested perfect with both sonic testing and Thermal Integrity Profiling, Harlan reports.
“A couple of times, we brought up antique car parts and old steel beams,” says Robin Gregory, KDOT Construction Manager. “You never knew what you would get into when drilling.”
The area experienced record-breaking rains in May 2019, with the river in flood condition. The causeway washed out three times and the contractor brought in some rocks to hold it.
“While the operators re-built the causeway, the remaining crews would fall back and work on the piers that were outside to the river channel to keep production moving,” Harlan says.
A.M. Cohron also worked long hours in rain and mud to keep the construction on track to ensure the substructure was in place before the seasonal river restriction.
“The challenge on a job like this is always the river; you never know when the next three inches of rain is going to come through and cause havoc on your plans,” Harlan says. “However, when we were able to work in the river, the crews made the most of every day.”
Installing Beams and Deck
A.M. Cohron built a temporary bridge to set the steel beams before the river became off limits. Massive bolts connect the steel girder beams to the underlying structure. KDOT staff members checked the bolts to make sure they had the right tightness.
The deck has a precise number of steel reinforcing bars, coated with an epoxy to keep them from corroding, set into a crisscross pattern and tied by hand, says Tim Potter, Spokesman for KDOT.
A.M. Cohron completed the concrete deck in three phases. Not having access to the area beneath the bridge for a concrete pump truck, the contractor used a Line Dragon on the middle section.
“I thought it was pretty amazing,” Wilson says. “It was a remote-controlled buggy that directed the flow of concrete. It had a large hose and placed the concrete on the deck exactly where they needed it. It was a really cool tool.”
Line Dragon, from Somero Enterprises in Fort Myers, Florida, is a remotely controlled hose handler. The equipment pulls and places the concrete. It features variable displacement hydraulics for optimal power. A.M. Cohron had used a Line Dragon on prior jobs and was familiar with its operation.
“While it can slow the pace a deck pour and take some extra manpower on site, it is much better than the alternative of dragging a slick line across the deck with nothing but labor forces,” Harlan says. “The line dragon had to be implemented on this project due to us needing to place pump trucks in the river bottom but unable to re-build access roads washed away.”
Wilson flew a drone on the U.S. 166 bridge project to obtain progress photos and videos on a biweekly basis.
“When all of the flooding came through, there was a spot with some erosion,” Wilson says. “Because I had taken some pictures of the bridge during the flooding. I was able to show why one area had more erosion than others.”
Wilson considers a drone an “excellent tool for our designers to be involved in the construction process without having to drive down to the project to see it.”
On Schedule Despite Challenges
Through rain, snow, and other inclement whether, A.M. Cohron kept working on the U.S. 166 bridge.
“I am really proud of how well our crews have performed on this project,” Harlan says. “They have found a way to stay on schedule, beat labor cost and safely build a quality project in adverse conditions, such as flooding and extremely hot Kansas summer days. I also can't say enough about how well the Winfield KDOT office has been to work with. I would say this is a partnership project and should be an example of how owner and contractor should work together to get the project completed.”
Likewise, Gregory praised the contractor for helping her deliver her last KDOT project before retirement.
“I’m glad I had an opportunity to work with A.M. Cohron,” Gregory said. “They have been tremendous to work with. Everybody worked together, communicated together and made it a great project.”