Crews on the Tennessee Department of Transportation’s $54 million Interstate 240 MemFix 4 project in East Memphis are using accelerated bridge construction methods while building three new bridges and rehabilitating another bridge.
“It adds room for an auxiliary lane and, primarily, addresses seismic and foundation concerns,” says Ted A. Kniazewycz, Director of the Structures Division for TDOT.
The four bridges, in close proximity to one another, were built in the late 1950s and early 1960s and have experienced structural deterioration. TDOT has provided periodic repairs but decided it was time to replace the three bridges. Additionally, the new bridges will enable the department to finish widening I-240 in this area.
“The work will open up space to add additional lanes,” Kniazewycz says.
About 138,000 vehicles travel on this portion of the interstate daily. On the road passing above the interstate, receiving the new bridges, traffic counts are about 50,000 vehicles daily.
Kiewit Infrastructure South Co. of Omaha, Nebraska, received the contract to serve as construction manager/general contractor to build the bridges. The company participated in preconstruction and design activities, providing the department information about pricing, scheduling, construction phasing and sequencing.
“It gets the contractor’s expertise incorporated into the design, which makes the project more efficient,” Kniazewycz says.
Accelerated Bridge Construction
TDOT assessed various methods to replace three bridges and decided on a process in which the bridges would be built off the alignment and then moved into place. The department had used a similar process to build eight bridges in Nashville. TDOT used the CM/GC method on its Nashville project, too, and it selected Kiewit for that job as well.
The advantage to the method is the replacements will occur during the closure of the interstate and bridges during 18 weekends, starting in summer 2018 and finishing in summer 2019. On each bridge, demolition will start on a Friday evening, with crews removing the superstructure, and then placing the new bridges. Paving, striping and installation of concrete barriers on the outside will occur on Saturday and Sunday as part of a 57-hour, weekend closure.
“These periods are much safer for the contractor to work in, because he does not have to worry about working around live traffic and has complete access to the site,” Kniazewycz says. Additionally, “the public is willing to accept the short-term closures rather than having lanes reduced for two or three years, with backups all of the time. The amount of work that takes place on a weekend is what makes the project unique.”
Brandon Akins, District Engineer for TDOT, explains that the four-bridge project would have taken three or four years if traditional methods were used.
“We’re doing a large amount of work in a short period of time,” Kniazewycz adds.
Work includes repairing foundations. One lane in each direction on the interstate is closed during the project, which allows contractors to move equipment around and replace or strengthen foundation structures.
The Four Bridges
The bridges include two on Poplar Avenue, one on Park Avenue, and one for the Norfolk Southern railroad, all of the bridges pass above the interstate. Work began in January. On all of the bridges, the contractor is using an accelerated concrete with a rapid set.
“The most interesting piece of the project is construction of the railroad bridge and coordination with Norfolk Southern during the preconstruction and construction,” says Dave Paris, Project Manager for Kiewit.
Kiewit built a 338-foot-long replacement railroad bridge on a temporary alignment parallel and next to the old 316-foot-long, six-span bridge. The trains shifted to the replacement bridge and the old bridge demolished, and crews improved the H-pile foundation and reinforced concrete abutments, working behind barriers. Train traffic continues uninterrupted. Norfolk Southern has placed flaggers to ensure safety and will place the new track.
The new bridge has steel-plate girders and a steel deck. Once the new bridge foundations are ready, crews will demolish the old bridge and slide the new, temporary one into place and then secure it during a weekend, with train traffic stopped.
“That steel bridge on the temporary alignment will be slid over and used for the permanent bridge,” Akins says. “That is something very unique.”
Poplar Avenue requires two new bridges, each with two spans. Westbound, crews are building a 263-foot-long, steel-plate girder bridge with cast-in-place concrete deck modular units, with minimal joints. That added to the weight of the bridges but minimized the amount of cast-in-place concrete pours required once the bridges reach their destinations.
“The Poplar bridges are unique in my experience,” Paris says. “It’s a blend of accelerated bridge construction techniques. It also has long-term quality and durability elements as well.”
Kiewit crews are building the Poplar Avenue bridges about 2 miles north on the side of the interstate near an interchange. As part of the accelerated bridge construction plan, crews installed a micropile foundation under the existing bridge to provide intermediate support for the new structure.
“Micropiles are good, especially when you have a confined space,” Akins says.
Once constructed, the bridges will be moved to each bridge’s final location and then placed on the reinforced concrete abutments, after the old bridge is demolished. The bridges will need to pass under two underpasses, so the new structures could not be too tall.
Eastbound, the new bridge will be 222 feet long and also will feature steel-plate girders and cast-in-place concrete deck modular units. This bridge also will have reinforced concrete abutments with improved pile foundations.
Kiewit will mobilize two large cranes to pick up the bridges in four places, which weigh up to 1 million pounds each. The bridges will be rolled from their construction site to the bridge location with self-propelled modular transporters.
“There is a lot of specialty work and equipment,” Kniazewycz says. “That’s what you need to get a job like this done in a short order of time.”
At Park Avenue, Kiewit will rehabilitate a five-span, 291-foot-long bridge. The work includes retrofitting an abutment with steel H piles and seismic resistant improvements.
“It has taken a lot of coordination with a lot of different parties, going toward a common goal,” Paris says. “That goes back to the CM/GC process. The team environment created through the CM/GC process leads to the success during construction. The relationships built are good.”
Work continues on budget and on schedule for a summer 2019 completion. “It’s been a very successful project thus far,” says Kniazewycz.
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