April 28, 2008

Infrastructure

Repair work begins on Pitt River bridge

Rebar column collapse unlikely to delay project completion

RICHARD GILBERT

staff writer

Workers building the new Pitt River bridge are assessing the damage and developing a plan for repairing the structure after a rebar column toppled.

A nine-metre tower of rebar, which will form one of the support pylons for the bridge, fell over in the early hours of April 14 when a crane came into contact with a guy wire.

The B.C. Ministry of Transportation owns the bridge and the general contractor is Peter Kiewit Sons Co.

“The structural engineers and designers are reviewing the condition of the pylon and rebar, and working with Kiewit to provide a suitable repair procedure which will ensure the structural integrity of the bridge,” Susan Williams, Ministry of Transportation spokesperson, said in an email.

“Any concrete damage was minor in nature and can be repaired with standard procedures to allow the next lift to be poured on top as planned.”

Repairs are scheduled to begin the week of April 21 and are expected to continue without impacting construction on the rest of the site.

“The detailed repair procedures are still to be determined, but will likely include straightening and appropriate testing of the lower bars, fabrication of a new rebar cage and minor surface repairs to existing concrete,” Williams said.

Despite this setback the bridge is scheduled for completion in late 2009.

“The remaining five pylons are proceeding on schedule without impact,” she said. “Any delay to the damaged pylon will be recovered by bringing in additional resources and working extra shifts if necessary, such that the overall bridge schedule will not be impacted.

The ministry also said it was not possible for the nine metre tall rebar tower to fall into traffic on the old bridge running through the construction site.

“It (the rebar lift) is mechanically coupled to the previous rebar lift which is in turn embedded in concrete,” explained Williams.

“The couplers are stronger than the bars themselves, so bending over of the cage in place is the worst that could occur.”

The cost of the repairs is not known at this time. The contract is a lump sum, fixed-price contract and as such, any repair costs are included in the contract price.

The contractor is in the process of building part of each of the six supports for the bridge deck. The supports are built by pouring concrete into stacked rebar cages.

At about 6:30 am on April 14, one of the supports was damaged and a tower of rebar fell over. Initial reports indicated that one of the guy wires holding the rebar in place was severed by a crane operator and another one was hit.

However, a ministry spokesperson later said that wasn’t the case.

“The crane did not cut the guy wire. The crane body came in contact with one of the corner guy wires, pulling the cage over,” said Williams.

“The crane was not performing a lift at the time of the incident. It was being repositioned.”

No one was hurt in the incident. The old Pitt River Bridge is a swing bridge that spans the Pitt River between Port Coquitlam and Pitt Meadows, B.C.

The bridge is part of Highway 7, carrying the Lougheed Highway across the river. It is being replaced with a new cable-stayed bridge consisting of eight lanes, along with a new overpass to replace the nearby Mary-Hill Bypass-Lougheed intersection.

The project is scheduled to be complete in 2009.

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