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Dismantling Port Mann Bridge is a delicate operation

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An iconic piece of Lower Mainland history is being dismantled piece by piece above the Fraser River where just 50 years earlier, crews were busy putting it together.
Dismantling Port Mann Bridge is a delicate operation

An iconic piece of Lower Mainland history is being dismantled piece by piece above the Fraser River where just 50 years earlier, crews were busy putting it together.

The steel arches of the old Port Mann Bridge, known for their bright orange color, are slowly being cut into chunks and hauled away.

The old bridge, which used to be the longest of its kind in Canada, rests in the shadow of the new 10-lane Port Mann bridge which is 2.2 kilometres long and 65 metres wide.  

Its towers reach 75 metres above the deck.  The last two lanes are nearly complete.

It is one of the longest and widest cable-stayed bridges in the world.

Greg Johnson, communications manager for Transportation Investment Corporation, said the dismantling process is complex and delicate. The arch provides the structure’s strength so engineers must properly support it before removing parts. Johnson said engineers used blueprints from when the bridge was being built in the 1960s to learn how crews supported the arches.

“The process is going in reverse, really,” Johnson said.

He explained that crews are working from the middle outwards, essentially retracing the steps the original crews took. Braces and stay towers similar to those used while building the bridge are in place for the project. The towers’ long cables keep the arch in place as it is dismantled.

Additional supports will be fastened to piles driven into the riverbed. After the pieces are cut by workers with thermal lances, cranes lower them onto barges which take the steel to be recycled.

“It’s a complex challenge, there’s only one Port Mann Bridge and taking it apart is as unique a job as building it,” Johnson said.

It the old days, Johnson said, the entire bridge could be blasted into the river below. But now workers must take fish migration patterns and shipping traffic into account and work around them.

After the arch work is done, workers must continue with underwater bridge pedestals, which do require some explosives.

To reduce damage to the river and its fish, bubble curtains will surround the blast area. And minor blasts will preempt the larger ones to encourage fish to leave the area.

He estimates it will take another eight to 12 months before the process is complete.

The bridge is part of the Port Mann/Highway 1 Improvement Project which includes construction of a new  Port Mann Bridge, widening the highway, upgrading interchanges  and improving access and safety on Highway 1. The project is 37 kilometres long from the McGill Street Interchange in Vancouver to 216 Street in Langley.

by Russell Hixson

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