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Fri November 15, 2013 - West Edition
The emergency replacement of a span of the Interstate 5 Skagit River Bridge in Washington State (linking the communities of Burlington and Mount Vernon) is fully complete as of mid-November. PCL Civil Constructors completed the third phase of the project — the steel structural upgrades to the three spans that were unaffected by the accident which had one of the four spans above the water collapse when an over-sized semi-truck hit critical steel supports on May 23.
The nearly $20 million project — financed by Federal Emergency Relief Funds, had the temporary span in place on June 19 and the replacement span installed on Sept. 15. The bridge itself, 640 ft. (195 m) long (four connected spans), has two lanes in each direction and a median dividing them. More then 71,000 vehicles cross the bridge on a daily basis.
Repairing the bridge was a priority project for the Washington Department of Transportation (WSDOT) and that was reflected in the rapidity of the awarding of the contract to install a temporary span to Guy. F.W. Atkinson Construction LLC ($8.1 million). The bridge collapsed at 7 p.m. and the contract was signed at 10:30 a.m. on May 24.
Atkinson staff and crews, along with equipment and traffic control services, took over the site rapidly.
“It was to get the bridge up as fast as you could,” said Atkinson Engineering Manager Charlie DeGasparis. “We replaced the span with two 24-foot wide two-lane bridges supplied by ACROW Bridge, which is similar to a Bailey bridge.”
The bridge consisted of prefabricated parts that were assembled in sections on site (8 by 10 ft. [2.4 by 3 m]), all designed to meet traffic stress, and then pushed into place as completed.
The collapsed span (160 ft. [49 m] long) and 40 ft. (12 m) above the water, could only be installed once the debris from the collapsed span was collected. This first phase began on May 25 and ended on June 19. The demolition was supervised by the National Traffic Safety Board (NTSB), which treated the collapse as an incident.
“It was a slow, meticulous process,” said DeGasparis, “and the majority of the steel floor beams and all the main girders were underwater in a three to four knot current river. The divers had quite a hard time. Truss members above the water were sheared and hoisted onto a barge while below the waterline the pieces had to be cut by divers with underwater torches.”
The diving crews were provided by Global Diving & Salvage. The NTSB wanted the debris recovered intact as much as possible.
While the debris was being removed, Atkinson engineers and crews planned the installation of the replacement bridge via designs for the concrete pedestals, the bridge erection scheme and securing the bridge components from ACROW, which included floor beams, deck panels and individual truss pieces. ACROW provided supervision and technical assistance personnel.
“With the limited space that we had up there, we assembled the pieces and pushed them over the gap and assembled more until it was bridged,” said DeGasparis. “We started getting pieces on May 26 and by the time the demolition was complete, we already had three-quarters of one span complete.”
A Grove RT760E 60-ton (54 t) rough terrain crane was used to erect the pieces of the bridge. On average, there were between 30 to 50 construction personnel on site working two 12-hour shifts per-day. Several 10,000 lb. (4,536 kg) forklifts were also used, as well as a John Deere 544K front-end loader. Because of the location of the project and the need to start quickly, Atkinson rented all its equipment from United Rentals via its local office in Burlington, which also was responsible for maintenance.
Other major subcontractors included Pacific Pile & Marine (for Marine Equipment), Global Diving & Salvage (for diving), Rhine Demolition, Apex Steel (steel erection), and Novito Construction (for Traffic Control).
The existing substructure was used to support the temporary bridge via the installation of 6-ft. (1.8 m) tall pedestals to support it.
“We had to modify the existing piers as the truss that collapsed had a deeper roadway,” said DeGasparis. “The concrete pedestals, approximately 10 cubic yards each, were formed and cast on the original bearing surface, providing a new higher bearing elevation.”
The work progressed quickly, with the pier retrofit completed by June 9, the first part of the bridge installed by June 10 and the second part by June 15. The expansion joint retrofit was completed by June 17, the paving done on June 18 and the first vehicle crossed the bridge on June 19.
Atkinson also did some work on an adjacent span as the truck which caused the collapse clipped several sway frames as it crossed the bridge.
“Some bent members had to be heat straightened or replaced,” said DeGasparis. “The cooperation between WSDOT’s engineers, our engineers, ACROW, and the contractors and subcontractors was crucial to the success of our phase. It had to be done quickly, but it had to be done right and that thought was ever-present.
“It was a good experience. Because it was such a high-profile, fast-paced project, the coordination and teamwork had to be extraordinary and it was,” he added. “Twenty-four/seven shifts takes a toll on everybody, but for everyone who loves doing what we do, this is what you live for. It was a rewarding feeling and proud moment for all crews after the first vehicle crossed the bridge.”
The second phase of the project saw the Max J. Kuney Company install the permanent span, which required the ACROW bridge to be removed and disassembled and the new precast concrete girder span set in place.
Kuney was awarded the $6.87 million contract on June 18, with work beginning on June 20 and by Aug. 13, crews began the process of setting eight enormous concrete girders to support the new roadway, which was completed in three days. After this was completed, crews spent the following three weeks working on the final roadway, including the deck, barriers and other key components.
The girders were installed via the use of two cranes — one on the northern dike of the Skagit River and the other on a barge in the river, which worked together to lift each girder into place. Each girder had an approximate width of 162 ft. (49 m) and weighed around 168,000 lbs. (76,204 kg).
Prior to the girder installation, starting in early July, crews drove piles into the river to establish temporary work platforms to support the new bridge span during construction.
At the same time, a rail system to move the new bridge span into place was set up. This required, on the east side of the bridge, for crews to drive piles that held up the temporary span after it was shifted out of the way to make room for the permanent replacement.
Parsons Brinckerhoff led the design for the design-build bridge project, which had the actual road section slid into place on Sept. 14, a process that took 19 hours and required the closure of the bridge. The new bridge was open to traffic the next day at 2 p.m.
This part of the work required serious planning and a set of choreographed steps series to slide and lower the sections into place.
“Starting Saturday evening, contractor crews used a complex system of hydraulic jacks, Teflon pads and long steel rails to lift and move the two sections of the temporary span onto a work platform for disassembly,” said a WSDOT press release. “Then they used a similar set-up to usher the new, 900-ton concrete span into place.”
This required the services of bridge-mover Omega Morgan to safely “swap the spans.”
“Although crews encountered some complications along the way — including the time-consuming process of cutting through thick metal plates before being able to lift the temporary span,” stated the press release, “they still finished building and relocating the bridge more than two weeks before WSDOT’s Oct. 1 deadline.”
WSDOT’s press release acknowledged the hard work that Kuney and the subcontractors put in, noting that they “overcame numerous hurdles since starting work on the permanent span in mid-June, including a demanding schedule, complex and overlapping activities and wet weather. They worked days, nights and weekends to build the new span in 66 days, hitting a major milestone in mid-August with the setting of eight enormous concrete girders to support the new roadway.”
With its part of the project completed, Kuney crews removed its equipment and the temporary platforms from the riverbed.
“Our team was pleased to be a part of restoring this very important highway connection for the Skagit community and the state,” said Kuney Company President Max J. Kuney.
As mentioned, PCL crews worked on the steel superstructure of the three spans that did not collapse and effected repairs. This third phase of the project is worth $2.7 million.
“We are placing new steel members on the ends of each existing spans to give the bridge more redundancy and we are also replacing all of the sway frames — cutting them out and putting in new ones,” said Bob Lewis, PCL’s project manager, “in order to increase the vertical clearance of the entire bridge structure. The existing sway frames are arched down to the steel column posts and those are the members that are susceptible of getting hit by oversize loads. They are being replaced with horizontal members that will increase the vertical clearance to 18 feet.”
PCL could only begin work after the permanent span was installed in order to allow Kuney to focus its efforts, and this prevented PCL engineers and crews from examining the site.
Due to the time constraints and the inability to access the site prior to ordering steel PCL had to base its dimensions for the shop drawings on the as-built drawing dimensions. On a normal structural steel project, the contractor would be responsible for field verifying all dimensions prior to ordering steel.
“It was a month’s process to secure the structural steel and we picked up a month by ordering in advance of field measuring,” said Lewis, who noted that about 34 tons (30.8 t) of steel was removed for recycling and 74 tons (67 t) of steel should be installed. PCL has 15 iron workers and four laborers responsible for traffic control on site, working eight hour shifts from Sunday to Saturday (morning).
“The main challenge is getting things to fit,” said Lewis. “It’s just a little slow and tedious, but we’re getting there. We are basically retro-fitting an existing steel structure and we’re progressing on schedule — the crews have developed a good rhythm.”
Other work includes rivet removals and painting underneath the structure.
The steel, I-beams, gusset plates, stiffener plates, and other parts are stored in a temporary yard and every day the steel need for that night is loaded into a 36 ft. (11 m) — 2 axle Ledwell trailer via a Genie GTH-842 8000 lb. (3,629 kg) forklift. Also being employed are Genie Z-30/20N personnell lifts, JLG 10,000 lb. (4,536 kg) Skytrak lifts, Honda EB5000X generators, and Slugger portable magnetic drills.
Lewis, who also looks after the equipment, noted that no new equipment was purchased for the project and that the company purchases equipment from dealers such as PACO in Seattle. When needed, PCL sends in a mechanic to do repairs.
Like the other major contractors, PCL crews are pleased to be part of the bridge replacement project.
“It’s important to get this community back to normal,” said Lewis. “Burlington and Mount Vernon have been hit hard economically because people are avoiding the area and nearby big shopping malls. We’re doing our best to get this project done before the holiday shopping season and get things back to normal.”