When the Missouri Department of Transportation (MoDOT) awarded the $33 million contract for rehabilitation of the eastbound Interstate 70 Blanchette Missouri River Bridge, they planned on full seasons of work in both 2020 and 2021.

General Contractor KCI Construction Company of St. Louis, Missouri, decided on a different plan: “They completed two years’ worth of construction in a single season,” said Andy Tuerck, P.E., MoDOT’s Area Engineer for St. Charles County.

Last year, KCI accomplished a full paint replacement, replaced expansion joints, and repaired the steel truss and approach spans of the bridge between St. Louis and St. Charles counties. In summer 2021, they’ll finish their work by taking about a month to seal the bridge deck with an epoxy polymer overlay.

The five-lane, eastbound I-70 Blanchette Missouri River Bridge and its twin westbound cantilever bridge carry an average of 150,000 vehicles daily, more than any other St. Louis-area bridge across the Missouri River. Opened in 1978, the eastbound structure last underwent major repairs when joints were replaced in 2006. MoDOT completed a $63 million rehabilitation of the older, westbound bridge in 2012.

When MoDOT awarded KCI the low-bid contract for the eastbound bridge in January 2020, they included a final completion date of December 1, 2021. However, with the large daily volume of traffic on the bridges, they wanted the majority of lane closures limited to the first construction season.

For the work specified in 2020, the project reduced eastbound I-70 from five lanes to four, with two lanes on the eastbound structure and two crossing over to the westbound bridge. That decreased westbound lanes from five to three.

“We had a pretty aggressive schedule,” Tuerck said. “We wanted all of the truss painted in one season because we knew they’d have to access it from the top of the bridge and we wanted to get bypasses out of the way. We didn’t want to winterize a job where people were crossing over the median and up against temporary barrier. For the girders underneath, we gave them more time if they needed it.”

Turns out, they didn’t need most of the second year. KCI started work in March 2020. When all the lanes opened to traffic in November 2020, they had finished everything but the overlay.

To accomplish all that work safely and efficiently in the tight space, “We had a ton of daily coordination between KCI, all our subs, and MoDOT,” said Ethan Renner, KCI’s Project Manager. “We also held weekly coordination meetings to plan upcoming work.”

With more than 10 subcontractors working on the job, “There were a lot of moving parts,” Renner added. “Each day started with a morning planning and safety huddle to keep KCI and all our subcontractors on the same page and moving toward the same goal. As a project team, we made it a top priority to keep all communication as open and transparent as possible.”

The bulk of the work centered around the painting. Crews used approximately 12,000 gallons of paint and 800 tubes of caulking material. KCI’s subcontractor, Thomas Industrial Coatings of Pevely, Missouri, brought in 45 to 60 industrial painters at any given time.

“We were working both the top and lower sides of the bridge, painting them both at once,” Renner said. “Doing all that work efficiently took a lot of equipment (see “Abundant Equipment” sidebar), so there was a lot of coordination with our subcontractor to make sure we knew what was coming and when.”

The project also used over 300,000 square feet of Safespan suspended scaffolding on the underside of the structure. “That allowed for access to paint and perform steel repairs to all the areas below the bridge,” Renner said.

During paint removal, the bridge’s lead paint required crews to completely tarp off their work area to make sure no lead escaped containment. As they prepared to apply the new paint, MoDOT and Thomas Industrial Coatings decided to switch from inorganic zinc primer to organic zinc.

“Inside the truss chord members, it’s difficult to get spray paint in there,” Tuerck said. “If you get it in too thick, it mounds up and cracks. The organic zinc is epoxy and just seemed to be a better fit with a $0 change order.”

Amidst all the painting, crews faced an additional challenge to their efficiency.

“In addition to the large amount of workers in a tight space, we also had to remove and replace 10 expansion joints across the full width of the bridge,” Renner explained. “During the replacement work, we basically choked off access to that area, so we needed a lot of coordination to get people in and out of the jobsite.”

Crews replaced the expansion joints in groups of two. Each operation took a couple of weeks.

To minimize the time with restricted access, “We ran day and night shifts during the joint replacements, and worked a lot of weekends,” Renner said.

To further speed up the work, KCI submitted a value engineering proposal to utilize shotcrete for the bridge’s barrier wall encapsulation, rather than cast-in-place concrete.

“That made it safer, faster, and more robust,” Tuerck said.

The quantity of work affected KCI’s recommendation. “The total length of the bridge is 3,680 feet, and the barrier wall encapsulation work took place on both sides of the bridge, so we were looking at roughly 7,360 feet of cast-in-place barrier,” Renner explained. “We saw the switch to shotcrete as a way to potentially pick up time in the extremely aggressive schedule. Instead of forming and pouring the encapsulation, we got rid of the forming and shotcreted the total length of barrier wall.”

In other facets of the work, KCI encountered unexpected challenges to their schedule.

First, in replacing four upper guide pins as part of the steel repair, “The material specified was a very high-strength, hardened steel,” Renner said. “When we went to purchase the material, we found it was only made in a few places in the country and had a three-month lead time. That posed some challenges from a scheduling aspect.”

In addition, “When we got into some of the steel repair work on the truss, it was discovered that a number of the repair areas had grown since the last bridge inspection,” Renner said. “In order to account for the added repair work, we brought on additional ironworkers and, in some cases, worked additional hours. In the end, we were able to complete all the additional repairs MoDOT requested while still meeting their road opening date.”

At that point last November, all the lanes on the eastbound and westbound bridges returned to their original configuration. When KCI tackles the overlay this summer, traffic impacts will be limited to one eastbound I-70 lane closure at a time.

In order to complete all the painting on the eastbound I-70 Blanchette Missouri River Bridge in one construction season, KCI and their subcontractors brought in:

• Five steel grit recycling units
• Five dust collection machines
• Five decontamination equipment setups
• Nine 1600 compressors, one 900 compressor, and six 375 compressors
• 12 manlifts ranging from 60 to 85 feet
• Two 6,000-pound reach forklifts and five 5,000-pound reach forklifts
• Four 20-foot access stages