Missouri DOT Reconstructs the I-435 South Loop to Minimize Traffic Issues

Recognizing a need to improve capacity and safety along the busy Interstate 435 South Loop, the Missouri Department of Transportation (MoDOT), as part of a $74.8 million project, is reconstructing six bridges and adding another lane in each direction from the Kansas State line to the interchange with I-470, I-49 and US 71, known as the Three Trails Crossing interchange.

“This piece of road is the heaviest traveled corridor in Kansas City on the Missouri side,” says Perry Allen, Project Director for MoDOT. “And, it’s our highest crash corridor, due to the pure volume.”

Currently 155,000 vehicles travel this 4-mile section of road daily, and that is expected to increase to 170,000 vehicles, as the area experiences rapid growth in new businesses, freight distribution industries and residential communities. The road was rated as having an “F” level of service. Adding the lanes will increase the road to 10 lanes, five in each direction, and take care of that greater capacity for years, Allen says. 

Originally constructed as a six-lane freeway in 1966, the I-435 corridor was expanded to eight lanes from 1983 to 1994. It creates a loop around Kansas City, Kansas, and Kansas City, Missouri. 

“All of the improvements from the original 1966 and 1994 build were being utilized and had reached their functional service life,” Allen says. 

Both the Missouri and Kansas departments of transportation have made improvements. Kansas DOT is working on a section a couple of miles away currently, and MoDOT is building the final section in need of upgrading in its state. Kansas DOT has closed a lane, creating traffic delays, as it replaces deteriorating concrete with new concrete pavement and rebuilding two bridge approaches.  

Design-Build Solution

Initial studies suggested removing one lane during construction of the additional lanes and the bridge work. MoDOT did not like that option, but had few alternatives. 

“There was no diversion corridor,” Allen says. “The property adjacent to the corridor is highly developed and did not provide opportunity for additional right of way to provide capacity, as well as it is the only East-West Interstate corridor on the south side of the Kansas City Metro area.”

MoDOT decided to award the project as a design-build project, with a challenge of constructing the project without eliminating an existing lane during peak travel hours, maintaining access to the interchanges during peak times and completing the work at a fixed price of $64.5 million. This is the department’s thirteenth design-build job since 2006. 

“We have not used design-build a lot, but we are accelerating it’s use,” Allen says. “We hope to use it more, because we are seeing the benefit of it. The relationship that happens between the owner and design-build team is so positive. You are working together. They know the goals.”

In addition to speeding up completion of the work, with the design and construction team, starting work while the design is completed, the department hoped to get creative ideas. MoDOT leaders met every other week with the teams vying for the job. It conducted trafficking models and provided that data to contractors. 

“The goal was to minimize impacts to the traveling public,” Allen says. “The winning contractor came up with a way of not ever taking a lane away during peak travel times. That was the big win.”

Additionally, the winning contractor, Radmacher Brothers Excavating Co. of Pleasant Hill, Missouri, proposed resetting the pavements service life to like new conditions. The new pavement is designed to last 25 or more years. Wilson & Co. of Kansas City, Missouri, served as the engineer of record. 

“We got everything we asked for at a fixed price and more,” Allen says. 

MoDOT cored the original and 1994 pavement. Most was in good condition. Radmacher proposed an 8.5-inch concrete overlay. 

“There are no overpasses or clearance issues,” Allen explains. “They also moved the bridges out. They were the only ones who came up with this concept. This was their teams’ ability to identify this opportunity the corridor was ripe for. It was out-of-the-box thinking. We got the best of everything.”

Road Construction and Rehabilitation of the Bridges

Radmacher began the work in January 2018 and was about 30 percent complete in August. The entire project is expected to be complete in May 2020. 

“People are going ‘Wow.’” Allen says. “There is so much equipment on site, and they are going so fast.” 

The project includes the reconstruction of six bridges, which were built in 1966 and not upgraded in subsequent years. They were built before mechanically stabilized retaining walls were used at bridge ends. 

“The bridges will be in new condition,” Allen says. 

Radmacher proposed shortening the bridges, pulling back the ends closer to the roads underneath and making them single-span structures. The existing bridges had supports between the traffic lanes. 

“That also helped them on safety improvements,” Allen says. “It also reduce the amount of bridge deck needed.”

All four of the new bridges have concrete girders. Two railroad bridges being rehabilitated with a new deck will continue to have steel girders. 

Additionally, the contractor will remove the loop ramps at the Holmes Road Interchange, add 12-foot inside shoulders along I-435, increase vertical clearance under the Wornall Road bridge, and build new taller and safer concrete barrier wall and longer merge lanes in critical locations. 

“This job would be most successful if it happens quickly and people are not negatively impacted by it,” Allen says. “What makes me proud is that the winning proposer puts the road back to like new condition.”

Project Partners

• Owner: Missouri Department of Transportation
• Design-Build Team: Radmacher Brothers Excavating Co., Pleasant Hill, Missouri, and Wilson & Co., Kansas City, Missouri