MONTREAL - Transport Quebec quietly released a report on Friday afternoon concerning inspections of the concrete slab that collapsed in July on Highway 720.
According to the report submitted to Transport Quebec in January 2011 by SNC-Lavalin, the walls which held up the multi-ton 'paralumes' were judged to be secure, but had not been physically inspected.
In fact the report specifically states that "It is worth noting that the supporting sills and and the walls holding the beams are excluded from the mandate [of this report]."
The report also says that the supporting walls underneath the paralumes were not specifically inspected in 2008, but that there were many signs of concrete spalling and flaking throughout the walls of the tunnel and on the sides of the sunken highway.
In its conclusion, the report recommends that the walls and "sills which hold up the paralumes be inspected" to determine if they are strong enough to support the structure.
Report looked at ice buildup
The main thrust of the report was to determine if the paralumes could withstand the weight of ice and snow during winter.
The report analyzing the strength and weight-bearing capacity of the concrete sunscreens and their supports relied on other inspections, namely the original plans for the structure built in 1970, a physical inspection of the Viger Tunnel performed in May 2008, and a photographic report done in March 2007.
The engineering report acknowledges that there was damage to the screens, and that they should continue to be monitored for fissures and cracks consistent with aging concrete.
Of particular concern in the report was a lack of perpendicular reinforcement, so any diagonal cracks noticed in the future should be immediately dealt with.
Slab collapsed in July
On Sunday, July 31, 2011 one of those concrete slabs came crashing to the ground as construction workers were working on the supporting walls.
A preliminary report by Transport Quebec says the workers repairing the walls removed too much of the supporting structure.
Nobody was hurt when the 15-metre 25-ton slab collapsed, but the Viger Tunnel was closed for a week while crews removed the wreckage, and installed support pillars for the remaining paralumes.
