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UPDATE: Line spacer to blame for Evergreen Line beam shift on elevated guideway

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by Richard Gilbert

Structural engineers have confirmed that the failure of a concrete spacer on the Evergreen Line project in Coquitlam, B.C. caused a large beam to shift during the construction of the elevated guideway.

staff writer

Structural engineers have confirmed that the failure of a concrete spacer on the Evergreen Line project in Coquitlam, B.C. caused a large beam to shift during the construction of the elevated guideway.

“The engineers completed a thorough investigation over the weekend, and as a further precaution additional bracing and supports were installed to ensure the guideway was stable and safe,” said Amanda Farrell, executive director of the Evergreen Line project. “It is important to note that it was a temporary concrete spacer that failed, and that the engineers have confirmed the permanent guideway structure is safe and structurally sound.”

A 300-tonne beam that is being installed as part of an elevated guideway on the Evergreen Line project at Como Lake and Clarke Road dislodged on March 14 at around 1 a.m.

A temporary concrete spacer that sits between the column and the lower part of the guideway failed, which caused the guideway beam to drop and rotate.

“On Friday, when the incident first occurred, the engineers came to investigate the situation,” said Farrell. “They then designed some braces and structural supports that were fabricated from steel off site. They were brought to the site over the weekend and welded into place.”

Structural engineers have determined the concrete spacer is the main issue, while the beam and the columns are sound. The supports sit between the columns and the guideway span to prevent any movement.

Farrel said other beams on the project have been supported by steel shims and jacks, so it was unusual to use the concrete spacer.

The spacing between the column and the guideway is a little bit greater on this span than other, which is why the concrete spacer was used.

Engineers replaced the failed spacer with a temporary metal spacer. Concrete spacers will not be used again as the project moves forward. However, Farrell could not say why the spacer had failed.

“The bracing and supports that were added this weekend will facilitate the movement of the beam back into place,” said Farrell. “The engineers are currently finalizing the plan to reposition the beam. When the beam is repositioned the road will be closed temporarily.”

The contractor EGRT Construction is responsible for making the repair, but Farrell could not say how much this would cost.

EGRT Construction, a consortium led by SNC-Lavalin, was awarded a $889 million contract by the B.C. Ministry of Transportation and Infrastructure in January 2013 to design, build and finance the Evergreen Line.

The $1.4-billion project will link the cities of Burnaby, Port Moody and Coquitlam with an 11-kilometre advanced light rapid transit line between Lougheed Town Centre in Burnaby and Douglas College in Coquitlam.

The project involves the construction of elevated and at-grade guideways, a two-kilometre tunnel, seven stations, power substations, train operating systems and parking facilities, as well as a vehicle-storage and light maintenance facility.

To see an initial report on the elevated guideway incident, read this article.

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