Overland Park is one of the largest cities in Kansas, with a population of nearly 200,000 in 2020.

It also is one of the state's fastest growing cities, with new residents flocking there to settle in the suburbs. As a result, traffic on U.S. 69, one of the city's main arteries, became more congested, increasing motorists' commute time to the city. Highway safety was a major concern.

To deal with the congestion, the Kansas Department of Transportation (KDOT) authorized a seven-mi., full-road highway reconstruction stretching from 103rd Street to 167th Street. A toll express lane were added in both directions. Vehicles can merge in and out of the express lane at designated access points and are electronically billed for the time they drive on it. U.S. 69 is the first highway in the state to implement this system.

Precast sound walls alleviate noise from traffic. More than 30 bridges as well as storm sewer and sanitary structures were reconstructed as well.

The 69 Express Project also included widening six interchanges to handle additional capacity, creating trails, sidewalks and other safety features, which are under the city's jurisdiction.

US69 Express Constructors, a joint venture between Ames Construction of Burnsville, Minn., and Emery Sapp & Sons of Columbia, Mo., is charged with completing the design-build project. The project broke ground in March 2023.

"This is the largest public works project in the history of the state," said Benjamin Bryant, project engineer of Ames Construction/US69 Constructors. "It's also the largest design-build project that the state's ever done."

Taking Advantage of New Opportunities

Kansas-City based Pretech Corp. was awarded the bid to supply the precast for the project. It is Pretech's biggest project to date.

The use of precast concrete for these items is standard for KDOT.

The precast elements include:

• More than 620 inlets and junction boxes ranging in size from 3 ft. by 2 ft. to 10 ft. by 9 ft.

• More than 51,000 ft. of reinforced concrete pipe from 15-in. Class III to 60-in. Class V.

• Approximately 3,050 ft. of reinforced concrete box culverts from single 4-ft.-by-4-ft. to quad 11-ft.-by-11-ft. for the storm sewer.

• Nearly 15,000 (600,000 sq. ft.) prestressed concrete sound wall panels of various sizes, with the largest measuring 14 ft., 8 in. by 3 ft. Some were as thick as 7.25 in. and weighed up to 3,600 lbs.

Pretech mainly specializes in utility jobs — pipe, inlets and culvert. The company had never produced prestressed concrete sound wall panels. To meet the project demands, Pretech needed a new plant to accommodate the job. Fortunately, a substantial lead time made this possible.

"One of the challenges was starting a new facility from scratch," said Mike Bundschuh, vice president of Pretech, who considers it an opportunity to expand.

An existing manufacturing facility in Tonganoxie, 20 mi. from Pretech's main plant in Kansas City, was procured and refitted as a precast plant to fabricate the panels.

All other precast products were fabricated at Pretech's main plant in Kansas City.

Prestressing the sound panels, something else Pretech had never done before, posed another challenge. Again, the company was up to the challenge.

"It wasn't that painful," Bundschuh said. "It was just a matter of getting a few people certified."

By the fall of 2023, the new plant was ready, the workers were trained, and production of the 7 mi. of sound panels began.

"This type of project is right up our alley," Bundschuh said. "The job's going well, and it gave us the ability to open another facility."

The first precast sound panels were shipped 40 mi. to the job site in April 2024. Pretech fabricated racks specifically for transportation of the panels. Each rack holds three. The racks are loaded on standard-sized flatbed trucks.

"These racks also allow us to carry the panels around on-site, allowing quicker delivery," Bryant said. "Once the panel racks are empty, they are loaded back onto the trucks and returned to Pretech's plant where they are reused for the next load."

Devising Four-Phase Installation Process

It took some time to determine the best process for installing the precast sound panels and to ensure everyone was on the same page. In the end, a four-phase process was agreed upon.

The four phases, in order, were:

• Drilling the shafts, setting a rebar cage, pouring concrete, then plunging the wet cure anchor bolts into the concrete.

• Setting the sound panel posts onto the concrete shafts. Then, once the panel is plumb, grouting the bottom of the post's base plate to the drilled shaft and screwing it into the anchor bolts to ensure water doesn't get underneath the post.

• Setting the sound panels.

• Painting the wall with an aesthetic coating to match other prior projects in the area.

"Once the initial process was nailed down, it's been fairly smooth sailing," Bryant said.

As with most highway construction, a big challenge is installing the sound wall while the highway is open for business. US69 Contractors are allowed to close one lane going each direction from 9 a.m. to 3 p.m. only. The rest of the time, live traffic is going in both lanes and both directions.

"We are aiming to be completed with the installation of the panels in August of this year," Bryant said.

Winning Outcome

Opening the Tonganoxie plant proved to be the right decision for Pretech. Already, it has procured a job for producing precast sound panels that will begin when the current work is finished. The new facility also will be used for overflow from the main plant and for the manufacture of mechanically stabilized earth (MSE) retaining walls.

"Moving forward we can continue to make not only sound wall panels, but other items that we wouldn't be able to handle at our primary facility," Bundschuh said.

Bryant, who had worked with Pretech before, would enjoy working with Pretech again.

"They have been awesome to work with on this job," he said. "They have helped us out in more ways than I can count."

While not yet completed, the project is proceeding well.

"We're meeting the major milestones and are on track to open the mainline by the end of this November," Bryant said.

(Article reprinted with permission from the National Precast Concrete Association.)