BY RICHARD GILBERT - Structural engineers are investigating an incident on the Evergreen Line project in Coquitlam, B.C. in which a large beam shifted during the construction of an elevated guideway.
“At about 1:30 Monday morning, a temporary concrete spacer that sits between the column and the lower part of the guideway failed, causing the guideway beam to drop and rotate,” said Evergreen Line project director Amanda Farrell.
“We don’t know the exact cause of that failure, but engineers are on the site right now investigating that. Structural engineers have been here since the incident occurred.”
A 300-tonne beam that is being installed as part of an elevated guideway at Como Lake and Clarke Road dislodged on March 14.
As a result, a section of Como Lake Avenue was closed in both directions. Como Lake Avenue runs under the rapid transit line.
“The beam itself and the columns are sound. The issue is the spacers,” said Farrell. “The structural engineers are doing a thorough investigation of what has happened, just to make sure it is safe and determine how they are going to rectify the situation.”
The elevated guideway consists of building a substructure for the foundations and columns, as well as a superstructure for the overhead guideway.
This is followed by track work and systems installation.
Column construction is complete along Clarke Road in Coquitlam and is continuing on North Road.
The elevated guideways are being constructed with a launching truss that moves from column top to column top.
The concrete segments are pre-cast at an off-site facility and transported to the site by low bed trucks.
The launching truss lifts the segments, while crews connect them together to form the overhead guideway beam. These beams span from column to column.
“This is a slightly different span than the other spans down North Road,” said Farrel.
“The spacing between the column and the guideway is a little bit greater than it is on other spans, and therefore has this concrete spacer, which we think might may have failed. (It) is somewhat unique on this span.”
Engineers replaced the failed spacer with a temporary metal spacer. This will be replaced with a permanent concrete spacer.
The Ministry of Transportation and Infrastructure said Como Lake Avenue between Clarke and North roads reopened at 3 p.m. on March 16.
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.
Construction of the two-kilometre Evergreen Line tunnel, which will run east of Barnet Highway in Port Moody to south of Kemsley Avenue in Coquitlam, began earlier this month.
To see an updated story on the line spacer responsible for the incident, read this article.