Oklahoma’s transportation department is modernizing an aging interchange with Interstate 44 to improve capacity and eliminate a bottleneck on Interstate 235 in Oklahoma City.

“It could not handle the traffic,” says Jeff Garder, Project Manager with the Oklahoma Department of Transportation (ODOT). “We are widening the interstate and addressing the drainage issues that had plagued the area for a long time. We also addressed safety concerns. There are a lot more efficient ways to handle and move traffic now.”

About 122,600 vehicles drive on this section of I-235 daily, and 90,000 motor on I-44 each day.

When complete, this project will become the first four-level interchange in the state, with the highest ramp 73 feet in the air.

At the time of its letting in 2018, the $105 million contract was the single largest project ever undertaken by the Oklahoma DOT. Federal and state money funded the project.

“The bidding and pre-construction phase of this project and the previous phase were very challenging,” says Reed W. Greenhill, an Estimator and Project Coordinator with project contractor Allen Contracting of Oklahoma City. “We worked diligently to ensure we had the best possible plan with regard to cost and schedule.”

The project included removing the former loop ramps at the interchange and adding two new flyover ramps, northbound I-235 to westbound I-44 and from eastbound I-44 to northbound I-235/U.S. 77/Broadway Extension, which take off in their own lanes, so there is no merging on and off at the interchange. Rather, vehicles merge farther down the interstate.

“There is never a bottlenecking issue, never a merge point at a high-traffic point,” Garder says. Plus “widening the ramps will really open things up.”

In addition to the two flyover bridges, the department added nine bridges, with various types of beams, to the interchange to facilitate 1-235 traffic over I-44 and over Deep Fork Creek. The three bridges spanning the creek did not require a marine operation, with all of the work taking place on land. Crews controlled sediment and erosion to avoid anything from entering the water.

“We built work roads and installed crossings to accommodate the material and equipment needs,” Greenhill says.

All together there are 8 million pounds of steel structure in the bridges.

The department purchased additional right of way, primarily to the east of the original interchange. Benham, of Tulsa, Oklahoma, assisted ODOT with the design.

Allen Contracting received the construction contract for the current phase in December 2018. The company was founded in 1987 and remains a family-owned business, with a storied history as a prime contractor on many of Oklahoma’s most challenging roadway projects.

The flyovers are complete with traffic moving on them. They are founded on drilled shafts and the abutments on steel pilings. The department used a mixture of girders, including steel and concrete tub girders on the curved flyovers. “It was a complex superstructure to build,” Garder says.

Allen Contracting’s subcontractor American Bridge Co. erected the tub girders for the flyovers and bearing assemblies, while Allen Contracting completed all substructure and bridge deck work. The same companies completed the new BNSF railroad bridge over I-235 in early 2018, rolling 2-million-pound a piece truss structures nearly a quarter of a mile into place.

On this project, crews used a 300-ton Manitowoc crane to hang the flyover steel girders. The tie-ins with the two bridges still under construction remain to be done. Nine bridges are complete.

Crews used GPS on the earthwork during grading operations. Most of the concrete paving is complete. Garder explains that Portland Cement concrete pavement was selected for the highway, bridges, and ramps due to its longevity.

“You do not want to get back in the middle of an interchange for maintenance,” Garder says. “Concrete is more durable and it is long-term and cost effective.”

Allen Contracting kept traffic flowing on two lanes in each direction through most of the project.

“Some of the most challenging elements of this project were maintaining the existing traffic movements while simultaneously constructing new bridge structures, retaining walls and roadway pavement,” Greenhill says.

There were some overnight lane shifts, intermittent ramp closures and night-time lane closures. The contractor built crossovers to enable I-44 traffic to stay open during construction. Bridge beam erections took place during full weekend closures and by shifting traffic.

“There are tons of ramps throughout the interchange, and we kept every one open for the entirety of the project, never shutting down traffic, which is really a feat,” Garder says. “Those two I-235 closures for the girders were the only full-weekend closures through the entire project.”

Garder credited the traffic control with helping to keep the job safe. Smart message boards and barrels warned drivers of the upcoming construction. ODOT also paid the Oklahoma Highway Patrol to be on the project daily during work hours, so any accident or breakdown in the work zone could be addressed quickly. Additionally, the officers sat in the pinch points with their lights on.

“That has really helped on this project,” Garder says.

He also praised the department’s communication efforts to keep motorists informed and to recommend people avoid the area to reduce congestion during construction.

“We did a campaign to try to convince the public to use alternative routes as much as possible to lessen the potential conflicts,” says Lisa Salim, Public Information Officer for the department. “We called it ‘Off Broadway,’ because this section of I-235 is called Broadway. We played off that. The public has been cooperative.”

The COVID-19 pandemic created some unanticipated challenges for the department, including managing work while crew members were out due to illness or exposure, and securing the needed precast concrete for the mechanically stabilized earth retaining walls.

“The manufacturing plants were cut to a lower production rate, which impacted the time we could build the wall,” Garder recalls. “These were challenges outside of our control.”

This project is scheduled for completion in early 2022.

The department has yet to let one last $16 million, one-year contract in 2023 to complete the reconstruction of the interstate. That will create a direct connection from North Lincoln Boulevard to northbound U.S. 77/Broadway Extension. Once all seven phases are complete, this will represent a nearly $300 million investment in highway infrastructure in the Oklahoma City area, according to the department.