Urban projects often come with issues like tight spaces or an abundance of utilities – but for the Interstate 64 at Jefferson Interchange project in St. Louis, Missouri, the challenges seemed to multiply.

First, “This project is only about a mile long running down I-64, but the work is very spread out and separated by local property owners, city streets, and either side of the highway itself,” said Andrew Wilder, P.E., Project Engineer for Prime Contractor KCI Construction Company of St. Louis.

In addition, demolition and new construction span MetroLink light rail tracks and an Amtrak U-turn spur. Throughout the project, KCI has overcome complicated access and coordination issues while dealing with bedrock of varying depths, unsuitable soils, and undocumented utilities.

The Missouri Department of Transportation (MoDOT) awarded the project’s low-bid, $24.35 million construction contract to KCI in May 2020. Work started in August 2020 and is expected to finish in fall 2022.

Funded through a cost-share agreement between MoDOT and the City of St. Louis Land Clearance for Redevelopment Authority, the project modifies an existing partial interchange with I-64 and adds a new, full interchange. Short collector-distributer segments between cross streets provide additional access to local roads. Due to improved mobility from those changes, crews are removing two ramps that won’t be replaced.

Because this section of I-64 is one of the last parts of the original interstate construction from the late 1950s and early 1960s, entrances and exits to the interstate and the surrounding city grid were out-of-date and built for significantly less traffic.

“MoDOT’s original intent of this interchange project was to take care of its existing system and replace aging infrastructure,” said Jennifer Wade, P.E., MoDOT Area Engineer for the City of St. Louis. “There were two old bridges in poor condition and a significant amount of needed pavement rehabilitation. That provided the opportunity to shrink the footprint of the existing interstate network and allowed for the disposal of excess right-of-way, which the city was then able to develop.”

A new Major League Soccer (MLS) stadium is under construction in that excess right-of-way. The I-64 at Jefferson Interchange project will support the higher volumes of traffic expected from the stadium, as well as the 2022 relocation of the National Geospatial-Intelligence Agency – the primary source of geospatial intelligence for the U.S. Department of Defense and national intelligence community.

Because this project doesn’t rebuild the interstate itself, “We have the benefit of building brand-new concrete pavement and bridges away from traffic without the need for complicated, temporary traffic stages,” Wilder said. “However, that does come with the challenge of getting equipment, material, and personnel around highly active highways and streets.”

To overcome that challenge, “We were able to find a few access points from local roads,” Wilder said. In addition, “Upon permanent closure of one of the old eastbound I-64 exits, we were able to keep the ramp pavement in place as it wrapped around and underneath I-64, creating a long-term construction haul road and access between the north and south sides of I-64.”

As work progresses, options increase. “Once we paved the new concrete outer roads and new ramps, access around the job greatly improved,” Wilder added.

However, “On the east end of the job, bridge construction starts in MoDOT right-of-way, spans over the MetroLink tracks, through the parking lots of several businesses, over the Amtrak U-turn spur, and into Union Station’s parking lot – all in only 900 feet,” Wilder said. “We’ve been able to work with local property owners to create multiple points of access around these fixed obstacles, but moving large pieces of equipment or unloading oversized deliveries continues to be a delicate operation.”

All the work around MetroLink tracks requires intricate planning and delicate operations.

“The tracks are constantly operational, averaging five to seven minutes between each train car,” Wilder explained. “All work over or within 8.5 feet of any track has to be done during their off-hours of 1:30 to 3:30 a.m., during an approved single-track operation where one track services both directions, or during a full weekend shutdown of both tracks. Metro charges lump-sum fees for each level of impact, so the cost has to be balanced with the construction schedule.”

For the complicated demolition of a bridge section over the tracks, KCI chose a full weekend shutdown.

Because the MetroLink track was constructed 25 years after the bridge being demolished, “The gap between the energized catenary wire system and the bottom of the old bridge deck was only about 4 feet,” Wilder said. “Existing columns were located about 20 feet on either side of the twin MetroLink tracks, and the span itself was only 60 feet long.”

For the demolition, “Not only did we have to install a track protection system of oak crane mats and large wooden beams to cover the rails, but we purchased and retrofitted a rolling gantry system to set onto the track protection system and roll underneath the bridge to shield the catenary wires,” Wilder said. “Careful measurements were taken between a 1:30 to 3:30 a.m. temporary power shutdown in order to fabricate the system to clear the wires by several inches and still fit underneath the concrete bridge deck.”

A month before the demolition work, Metro Transit alerted the public to a weekend shutdown of all train traffic and scheduled additional bus routes to compensate. “That meant that once we got started, very little could be done to stop the demo process,” Wilder said.

Metro allowed crews on the tracks at 1:30 a.m. on Saturday, November 14, 2020; they needed to be completely off the tracks by 3:30 a.m. Monday morning.

“The weather forecast showed a slight chance of rain that Friday night into Saturday morning, but only a half-inch at most was forecast,” Wilder said. “However, a 3-inch downpour started promptly at 2:30 a.m. and didn’t quit until sunrise, slowing us down and putting us about 6 hours behind schedule after the first 12 hours.”

Despite that challenge, “Our subcontractor (Premier Demolition of St. Louis) did a fantastic job of efficiently removing the old bridge span and actually completed the demo with 12 hours to spare,” Wilder said.

To build the replacement bridge in that location, KCI works around MetroLink’s regular schedule. For instance, for girder erection over the tracks, “A full shutdown would speed up the process, but we’re leaning towards spending a full week during the two-hour overnight window,” Wilder said. “Nightly costs to power down the catenary wires and the nighttime premium for our labor force are minimal in comparison to Metro’s lump-sum cost for the weekend shutdown.”

Throughout the project – before and during construction – MoDOT, KCI, and the design team work closely with MetroLink and the many other stakeholders in the corridor.

“Coordination between MetroLink, Amtrak, Union Station, and the MLS group is a constant endeavor,” Wilder said. “They often have strict guidelines or procedures when working on, over, or near their properties.”

For instance, “Both railroad companies require online safety training,” Wilder said. “All contractors, subcontractors, crane operators, etc., have to pass the training and carry their safety cards in order to be allowed to work on property.”

In addition to those entities, “We have coordination with a helicopter emergency medical service station adjacent to the project limits,” Wilder said. “They require notice when cranes or large booms are in the air so they can notify pilots to approach from a different direction.”

Ultimately, “These challenges are addressed by working through the process with our partners, with lots of communication and coordination to ensure that impacts are kept to a minimum,” said Scott Washausen, P.E., MoDOT Resident Engineer for the City of St. Louis.

• Owner – Missouri Department of Transportation; Jennifer Wade, P.E., MoDOT Area Engineer for the City of St. Louis; Scott Washausen, P.E., MoDOT Resident Engineer for the City of St. Louis
• Prime Contractor – KCI Construction Company, St. Louis, Missouri; Andrew Wilder, P.E., Project Engineer; Justin Cline, Project Director; Cory Patterson, Project Superintendent; Jason Leuthauser, Concrete Superintendent
• Lead Project Designer – HNTB, St. Louis, Missouri

Editor’s Note: This story is part one of our feature on the I-64 at Jefferson Interchange project. Look for part two – including how the construction plan adapted to inconsistent bedrock and undocumented utilities – in the December issue of Construction Digest.