A bridge project in northern B.C. that left engineers and constructors scratching their heads at times has won a Burnaby-based company recognition for successfully managing a job with more than its share of hurdles.
Binnie Construction Services Ltd. received the Award of Excellence for Construction Management and Supervision Services by the B.C. Ministry of Transportation and Infrastructure (MOTI) for the Fort Nelson River Bridge replacement project, a crossing completed late last year about 70 kilometres northwest of Fort Nelson.
The project included the replacement of an aging single lane acrow bridge superstructure built in 1984, which was “more a temporary structure” than a long-term bridge, says Bill Smith of Binnie Construction, who was retained by the ministry to oversee the project.
The new 430-metre two-lane crossing was originally designed to be installed on the existing concrete and steel bridge’s foundation. But in the world of bridge construction, things sometimes don’t work out the way they are planned.
Construction commenced in November 2015 with scheduled completion 12 months later. An extension to June 2017 was granted by the MOTI when the bridge deck was revamped from precast to a cast-in-place concrete, says Smith.
Initially, engineers specified the precast deck design to expedite construction in winter, but general contractor Forbes Industrial Contractors of Prince George proposed a cast-in-place concrete deck with a longer life and lower maintenance costs, says Smith.
But that was not the end of design changes.
Another contract extension to September 2017 was given by the MOTI because of a number of unforeseen foundation problems with the 1980s bridge. Its piers and abutments had to be bolstered to meet modern-day design specifications, says Smith.
Additional piles were driven into land piers and the north abutment was demolished and replaced.
An ice bridge was constructed in December 2015 to act as a platform to drive piles for in-stream piers and to cast concrete for diaphragms between the piles and complete pile cap work, says Smith. An early spring thaw, however, caused a schedule setback.
“The ice broke up and it destroyed all the formwork and the rebar we had in place,” Smith explains. “Fortunately, we had piles in place and armour around them.”
Completing the work in spring and summer wasn’t an option because of high water so the following December a second ice bridge was built to finish the pile caps for two of the piers, he says.
Smith, who retired from the MOTI in 2010 after 38 years of service and has been working for Binnie ever since, says the acrow bridge was moved laterally 12 metres downstream onto steel pier andabutment caps, founded on steel pipe piles. It was used as a detour crossing during construction of the new bridge.
A hydraulic jacking system pulled the temporary bridge sideways over the pier cap extensions and was surfaced with a steel plate and “greased Teflon” for ease of movement. The move was scheduled to take six hours but an unexpected snowfall hampered the job, adding another 10 or so hours, says Smith.
Completed last fall, the new bridge has a superstructure founded on three rows of steel girders, says Smith.
“It was a very challenging project. A lot of issues happened,” says Smith, noting another obstacle was a highway washout that delayed the shipment of girders in the spring of 2016. “We had to find alternative routes.”
The province provided $19.6 million toward the $35 million project while the federal government added $15.4 million. Binnie’s contract was for $1.4 million.
While the bridge project was unusual, that in itself, isn’t unusual.
“No two bridge projects are ever the same,” Smith says, adding with repair and retrofit work increasing in B.C., engineers and constructors can expect to see more challenges ahead.
Structural engineers for the project were McElhanney.
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