In September, a steel cap that supported the bridge was damaged, causing the bridge deck to sag and leading highway officials to close the road and route traffic to Highway 1 on the other side of the Fraser River. Officials still don’t know what caused the cap, which is one of several on the bridge, to collapse, leading the deck to sink and come to rest directly on a support beam.
The bridge was eventually repaired and the deck now sits on a new support.
Inspection reports obtained through a Freedom of Information request filed by the New Democratic Party in November and later posted online show that both the cap that collapsed and many others had “medium to heavy corrosion.”
That corrosion had been detected at least as far back as 2010, a year after the bridge underwent a major rehab project that saw rotten piles and timber and cross caps replaced, according to the reports.
In each of the reports, which were filed between May 14, 2010 and April 28, 2015, the author writes, in all-capital letters: “BLAST AND PAINT ALL STEEL CAPS BEFORE LOSS OF SECTION IS TOO EXTREME.”
Maintenance work notes on the first report recommended a range of repairs and upgrades, including replacing corroded steel caps as needed, trimming trees, replacing rotten piles and replacing broken and rotten rails.
Over the following five years, the need for the same work was noted in each report. A seal in a specific deck joint first recommended for work in 2010 was still being suggested in 2015.
The inspector also suggested installing flares in each report.
Chief bridge engineer Kevin Baskin said that the corrosion is rust, caused by the decades-old bridge’s design, which sees water trickle between concrete girders in the bridge deck onto the steel caps below.
Corrosion is to be expected, Baskin told The Record, especially for structures in the rainy Lower Mainland.
“Bridges are in a very harsh environment and things like corrosion do happen.”
And while taken to its final state, corrosion can cause “concerns regarding the state of the bridge,” Baskin said the report suggests the inspector didn’t believe it to be a safety concern.
That is, in part, because of the importance of those rusting caps and the multiple redundancies on the bridge that keep it upright even if one piece fails.
Baskin and Norm Parkes, the executive director for Highway Operations, said engineers in the department will try to learn from the situation. Parkes also said the ministry had increased funding to repair crossings similar to the Dewdney Bridge by 50 per cent.
NDP MLA George Heyman said the report shows the ministry had identified problems with the bridge in years prior to its closure, but had done nothing.
“There were issues raised and yet nothing was done before the bridge would actually sag,” he said. Heyman, however, couldn’t point to any specifics in the report as evidence of the ministry’s inaction.