The Missouri Department of Transportation’s $278 million Interstate 270 North Design Build Project will add lanes, replace bridges, update aging infrastructure and reconfigure interchanges to reduce crashes and increase reliability in the busy freight corridor.

“Our primary goal is to improve safety by improving how vehicles move throughout the corridor,” says Eric Kopinski, I-270 North Project Director with the Missouri Department of Transportation (MoDOT). “The corridor was built in the 1960s when traffic volumes were lower. But higher volumes, along with pavement in poor condition, deteriorating bridges and few spaces for pedestrians and cyclists, dictated an overall plan to improve the corridor.”

About 140,000 vehicles drive on this section of I-270 daily, with 18 percent heavy trucks. It is one of the most traveled interstates in Missouri.

“Regionally and nationally, this corridor is critical,” Kopinski adds. “And the condition of it necessitated emergency repairs to keep traffic flowing well.”

The corridor had higher crash rates than other roads in the region. Eastbound I-270’s crash rate is 40 percent higher than the state average for interstates.

The I-270 project, from McDonnell Boulevard to Bellefontaine Road, entails widening 8 miles of highway by one lane in each direction to make four lanes, adding 12-foot-wide shoulders, completely reconstructing 18 bridges from the foundations up to bring them up to current design standards, and creating 10-mile-long multiuse paths on both sides of the highway. The project also includes signal updates and replacements throughout the corridor.

“It gives commuters safe passageways,” says Jason Highley, Senior Project Manager with Millstone Weber of St. Charles, Missouri, which received the design-build contract in December 2019. Parsons Corp. of St. Louis, Missouri, serves as the engineering partner.

Millstone Weber, founded in 2014, has grown into a prominent heavy construction contractor in the Midwest. The company works in multiple states, with an office in Centennial, Colorado. In 2020, Millstone Weber became employee owned. The department opted for a design-build approach for several reasons.

“When we choose design-build projects for complicated projects, we see the industry innovate,” Kopinski says. “It helps maximize our limited funding and gives us tremendous value, fantastic ideas and great products.”

Millstone Weber developed complex phasing and traffic staging plans. In total, there were more than 64 closures, which were planned during the proposal phase – prior to award of the project. The design-build team also had some unique recommendations for the new ramp and proposed the first bus-only lane in Missouri to serve a metro station along the corridor and a community college.

“Many of those who live here depend on public transportation, so part of the requirement was to implement strategies that gave them better access to that system,” says Kopinski.

Highley adds, “Design-build jobs allow for a lot of flexibility for the contractor. We are able, through the design process, to bring in innovation, things new to the industry. MoDOT has been receptive.”

Several ramps, including the east- and westbound I-270 exit ramp at West Florissant, were permanently closed to give drivers more space to enter and exit the freeway. Crews also removed all of the cross-over slip ramps and converted the outer roads from two directions to one-way to enhance safety and improve mobility.

“It’s part of the new configuration in our design,” Highley says. “It will increase the mobility on the interstate, eliminating cross-over ramps. It makes it more streamlined.”

MoDOT and the design-build team used traffic modeling software and safety analyses to determine how ramp closures would affect traffic before proceeding. “We wanted to make sure the improvements and resources were well spent,” Kopinski says.

I-270 represents MoDOT’s largest project within the past 10 years. It required consistent and comprehensive public communication and contact with various audiences, so MoDOT implemented an inclusive, people-focused engagement-centered strategy that included community meetings, a project website, a monthly newsletter, a database of public comments, and weekly update calls for community leaders and emergency management personnel.

“There is a strong need to ensure that projects that impact communities move beyond mere engagement to inclusion of those who live, work and play in the impacted area,” says Nina Thompson, I-270 Project Communications Coordinator. “Our engagement strategies created “spaces” for the public to share their thoughts and concerns about the project, participate in celebrations in-person or virtually, and engage with us in an ongoing manner. They are a major part of the project, and we wanted them to see that this was an investment in the betterment of their community, and that we were the partners not strangers or sole owners.”

Millstone Weber began work in early 2020. Crews are working at various places along the corridor simultaneously. Construction began at both ends of the interstate, with crews working toward the middle. The Lindberg and Belmont interchanges are complete.

The widening is occurring to both outsides of the existing I-270. Reconstruction of 8 miles of outer roads also are taking place. Millstone Weber is working off a 3D model and using total stations and automated equipment for grade control and stringless paving.

Parson’s general design for the bridges was similar throughout the project, which provided some efficiencies in construction. Most of the bridges have concrete girders and a couple have steel girders.

At one of the bridges, the soil was contaminated. The U.S. Army Corps of Engineers removed the soil and disposed of it properly.

“A big focus of this project was how to rebuild while keeping the traffic on the interstate and the local roads moving,” Kopinski says. “We did the best we could while we made these critical improvements.”

Millstone Weber kept three lanes of traffic flowing in each direction during peak periods by working nights when weather allowed, consulting with a traffic engineer for real-time signal updates, collaborating with emergency responders and other stakeholders, and creating new configurations, separating workers from traffic with concrete barriers.

“We planned our staging to limit impacts, focusing on smaller work areas, and for shorter durations,” Highley says.

Most of the bridge demolitions took place during weekend closures with detours off of the highway. Rebuilding has happened in stages.

The department and the contractor have placed safety as a top priority. MoDOT reduced the speed limit in the construction zone.

In addition to completing the project, Millstone Weber managers – at MoDOT’s direction – have conducted monthly classes with public high schools along the corridor to generate interest in science, technology, engineering, math, and construction careers. This is the third year the company has participated.

“A number of students who went through the program two years ago are now in engineering or trade school programs, and a couple of them are working on this project,” Kopinski reports. “It’s been a rewarding process. They are playing a small part in making it successful.”

The design-build team is exceeding the established minority and women participation goals. Millstone Weber has conducted a significant amount of outreach into the trade community. The company has provided mentorship to small, minority companies. “Every trade has had great representation, and that’s been fantastic,” Kopinski says.

The project remains on budget and on time. It’s scheduled to open by the end of the year.

Photos courtesy of the Missouri Department of Transportation