EK E R C CT ER 9 E T J E T O S O R A P C VER UCTION O 4 S H OW 5 TE 2 CONSTR U O R E TE G A D T I S R T TDO ERATED B O G E T H E R T ACCEL T H E P I E C E S GR
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ARTN AND P H T I M S
PUT TING THE PIECES TOGE THER A NEW BRIDGE OVER OTTER CREEK
TDOT State Route 254 Over Otter Creek Accelerated Bridge Construction Project LOCATION
Nashville, Tennessee C L IENT
Tennessee Department of Transportation, Structures Division, Bridge Inspection and Repair Office SERVIC ES
Bridge Design Roadway Design
Before photos show how the bridge had become structurally deficient after more than 50 years of service. Central portions of the original abutments were the only components to stay.
TD OT S R 254 OVE R OT TE R C RE E K ABC PROJ ECT
high-traffic, two-lane crossing providing an east-west connection from the southwest section of Davidson and Williamson counties into Brentwood and Interstate 65, the existing bridge over Otter Creek on state Route 254 in Davidson County had become structurally deficient and functionally obsolete after more than 50 years of service. Too narrow for the traffic it was carrying, the deteriorating overpass was on the Tennessee Department of Transportation’s (TDOT) list to be upgraded as a repair project. Having worked on multiple projects together, TDOT solicited GS&P’s guidance in determining the most feasible approach for repairing the aging structure. After close collaboration with the Department regarding the bridge’s current condition and the possibilities for rehabilitation, GS&P advised that the timeworn crossing was beyond repair, and that replacing the portion of the bridge that supported the deck was the only viable option. This would involve removing the existing deck, beams and piers, and replacing them with a new single-span superstructure. “Like many bridges built around the same era, the existing structure was past the point of repair due to the amount of deterioration in the reinforcing steel,” explains senior structural engineer Ted Kniazewycz. “However, the substructures were in good enough condition to be preserved as part of the replacement. Reusing those in the new bridge configuration and replacing the existing superstructure presented the most cost-effective solution.”
“LIKE MANY BRIDGES BUILT AROUND THE SAME ERA, THE EXISTING STRUCTURE WAS PAST THE POINT OF REPAIR DUE TO THE AMOUNT OF DETERIORATION IN THE REINFORCING STEEL.”
TED KNIAZEWYCZ, SENIOR STRUCTURAL ENGINEER
Associates) used the site to construct the bridge superstructure using “match-cast” methods to insure that the units would join together once they were moved to the bridge abutment supports. Two precast units were fabricated adjacent to the bridge prior to the weekend. The cross section shows how the two units were joined in the center with a mechanical connection filled with high-strength, fast-setting, non-shrink grout to form the superstructure.
SR 254 Bridge over Otter Creek
Plan sheet of the superstructure with both units installed. The two units are joined in the center with a mechanical connection filled with high-strength, fast setting non-shrink grout. Old
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Showcase 9 Entry
8 1-mile section closed during the replacement weekend
Because of the high volume of traffic along this stretch of Old Hickory Boulevard (SR 254), GS&P worked with the client to determine the most effective and expeditious means of carrying out the necessary and complex bridge repairs. It was ultimately decided that Accelerated Bridge Construction (ABC)—a process that dramatically reduces construction time as well as long-term inconvenience to motorists—provided the best solution. A first-of-its-type ABC method for TDOT, this short-term total closure of a 1-mile section of Old Hickory Boulevard would allow crews to carry out their work around
the clock without being encumbered by road traffic. To be completed within a single weekend, the fast-tracked project included minimal roadway widening, substructure modifications, and full superstructure replacement and widening for the existing two-span bridge. Along with significantly reducing the project’s schedule, the ABC process would also result in significant sustainable and environmental benefits, including less disruption to Otter Creek and reduced carbon emissions, as extended traffic gridlock would be reduced.
Senior transportation engineer Mark Holloran discusses the key benefit of applying ABC methodology to the project versus a traditional phased construction approach: “This section of Old Hickory Boulevard often carries up to 30,000 vehicles a day. Given the heavy traffic volume on-site, executing the project in a more traditional way would have been untenable, and most likely resulted in a three- to six-month project schedule. By employing this particular ABC technique, the entire superstructure could be replaced in just one weekend.”
“GIVEN THE HEAVY TRAFFIC VOLUME ON-SITE, EXECUTING THE PROJECT IN A MORE TRADITIONAL WAY WOULD HAVE BEEN UNTENABLE... BY EMPLOYING THIS PARTICULAR ABC TECHNIQUE, THE ENTIRE SUPERSTRUCTURE COULD BE REPLACED IN JUST ONE WEEKEND.” MARK HOLLORAN, SENIOR TRANSPORTATION ENGINEER
PLANNING THE REPLACEMENT
BUILDING A NEW BRIDGE
widened allowing for the addition of 6-foot shoulders on each side of the overpass to improve sight distance for residents of an adjacent subdivision. After demolition was complete, Starting Friday, September 12, 2014 at 8 p.m., TDOT closed Old the site was cleared. Concrete from Hickory Boulevard from Chickering Road to Hillsboro Road to allow crews to replace the former bridge the existing bridge was repurposed as GS&P WAS TASKED WITH DEVELOPING A PLAN over Otter Creek. fill material, while As part of the comrebar was collected TO UTILIZE PREFABRICATED SUPERSTRUCTURE and recycled. prehensive project, UNITS THAT COULD BE CONSTRUCTED OFFJust after 6 a.m. GS&P was tasked with developing Saturday, the first SITE, INSTALLED, AND THEN JOINED TOGETHER a plan to utilize superstructure DURING A SINGLE WEEKEND ROAD CLOSURE. prefabricated superunit—one of two that structure units that weighed approxicould be constructed off-site, installed, and then joined together mately 225,000 pounds each—was during a single weekend road closure. The team also created plans lifted off the ground by two cranes for precast approach slabs and sub-footings to transition the bridge and then transferred to a third crane to the approach roadway. Once the existing bridge and section of roadway was closed and traffic detoured, demolition commenced at 9 p.m. The only portion of the original structure to remain were the central portions of the original abutments. Prior to the closure, these surviving bridge supports were
FRI. 9 pm
Demolition of the existing bridge began at 9 p.m. Friday. After demolition was complete, the site was cleared. Concrete from the former bridge was repurposed as fill material while rebar was collected and recycled.
SAT. 6 am
Just after 6 a.m. on Saturday, the first superstructure unit— one of two that weighed approximately 225,000 pounds each—was lifted off the ground by two cranes and then transferred to a third crane that moved it across the creek.
that moved it across the creek. Once both precast units were set in place, the concrete bridge rail was poured. By 10:30 a.m. the units were joined together using high-strength grout. span of 75 years was opened to traffic by 8 p.m. Sunday, coming in Weathering steel beams, which 10 hours ahead of schedule. don’t require painting, as well as “Our design solution successfully integrated the bridge’s endepoxy reinforcwalls into the prefabricated ing steel that CONSTRUCTED WITH MINIMAL DISTURBANCE offers enhanced units,” explains protection in Holloran. “This TO OTTER CREEK, THE NEW SUPERSTRUCTURE freeze-thaw allowed the entire HAS A PROJECTED LIFE SPAN OF 75 YEARS. conditions were superstructure to used, providing be cast in only two a durable, low-maintenance and pieces, and also provided an economical and structurally sound sustainable structure. A deck seal detail for attaching the units to the existing substructures.” “The single-biggest challenge of this project was getting the superwas also utilized to further protect structure from Point A to Point B without imposing any unfavorable the bridge. loads to the structure itself,” adds Kniazewycz. “So we designed it to Constructed with minimal disbe self-supporting once the concrete was cured onto the steel beams. turbance to Otter Creek, the new This let it function as a separate unit and handle the load capacity as superstructure with a projected life it was being moved. It was a great moment to see those two pieces finally come together. Everyone involved was delighted that by Sunday evening there was a nice, smooth road to drive across.”
Once both units were set in place, the concrete bridge rail was poured. By 10:30 a.m. the units were joined together using high-strength grout.
SUN. 8 pm
By 8 p.m. Sunday evening, the bridge was opened to traffic, coming in 10 hours ahead of schedule.
SAT. 10:30 am
SETTING THE PATH FORWARD
TD OT S R 254 OVE R OT TE R C RE E K ABC PROJ ECT
Executed without major long-term impact to motorists, the Accelerated Bridge Construction process used in the new bridge over Otter Creek eliminated months of inconvenient traffic backups, resulting in a reduced carbon footprint, “ and saving end users in both fuel and maintenance costs. The innovative ONCE WE STARTED pilot project was awarded the Grand DEMOLITION OF Iris Award (Best in Show) in the ACEC of Tennessee’s 2015 Engineering THE BRIDGE, Excellence Awards program. THERE WAS NO “This project signifies a bold step forward in embracing construction TURNING BACK. methodologies that could forever change how complex transportation ” projects are delivered in Tennessee,” says Kniazewycz. “The amount of planning in design and construction that was required to ensure the project’s success was staggering.” In addition to working closely with the client, the project also represented a coordinated effort between GS&P and general contractor Bell & Associates. “Once we started demolition of the bridge, there was no turning back,” notes Kniazewycz. “I was amazed at the high degree of redundancy the contractor built into this project to allow for anything that could potentially go wrong on-site. If something broke down, he provided backup—extra equipment, extra personnel, and anything else you could think of to make sure the project went as smoothly as possible. This effort truly emphasizes how a team approach, from design through construction, sets the path forward for greater projects to come.” The existing bridge structure included a pier that was located within a stream bed. The updated design requires no pier, which limits the need for accessing the creek, and the potential for any disturbance during maintenance.
“ THE OTTER CREEK PILOT PROJECT WAS A TREMENDOUS SUCCESS DUE IN PART TO THE DEVELOPMENT OF DETAILED CONSTRUCTION PLANS AND THE CLOSE COORDINATION BETWEEN THE ENGINEER, OWNER AND CONTRACTOR. ” TERRY D. MACKIE, PROJECT MANAGER OF THE BRIDGE INSPECTION AND REPAIR OFFICE AT TDOT
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PIC Mark Holloran, p.e. PM /PP Ted A. Kniazewycz, p.e.
John D. Brew, p.e. Katherine Ham Rodney C. Palmer Larry Ridlen, p.e. Tom Tran, p.e. Gary Young
A first-of-its-type ABC method for TDOT, the project served as the prototype for a much larger urban project in downtown Nashville—TDOT’s Fast Fix 8.
Terry D. Mackie, project manager of the Bridge Inspection and Repair Office at TDOT, confirms the project’s success: “The Otter Creek pilot project was a tremendous success due in part to the development of detailed construction plans and the close coordination between the engineer, owner and contractor. The positive results taken from the project will be applied to future efforts, further enhancing the transportation network and the environment. The main goal of this Accelerated Bridge Construction project was to significantly reduce the impact to the motoring public. By replacing this bridge in a single weekend closure, we accomplished that key objective.”
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