Troubles with the opening mechanism at a swing bridge in Wallaceburg, Ont., in the municipality of Chatham-Kent, will be addressed swiftly to safeguard against the possibility of creating a snarl of traffic along nearby Highway 40, says the municipality’s director of engineering and transportation.
"It's not a simple (situation)," said Adam Sullo following a June announcement that the bridge would remain closed to marine traffic that could not clear the structure while it is closed.
"We've done some temporary modifications right now that should hopefully prevent any issues for the next few months."
The 23-year-old Base Line Bridge — one of four that carries motor vehicles and opens to marine traffic along the Sydenham River in the community near Lake St. Clair — is part of a heavy truck detour around Lord Selkirk Bridge, a double bascule span bridge on Highway 40 whose load was reduced to 15 tonnes late last year because of a need for repairs. The highway connects Chatham and Sarnia.
The problems at the Base Line Bridge are relatively minor, but they carry the risk of the bridge getting stuck in an open position at a time when the volume using it has more than doubled the bridge's average daily traffic volume of 5,600 vehicles.
At issue is the structure's out-of-date programmable logic controller used to sequence the steps to open the bridge as well as the sensors that help keep bridges and vehicles safe from damage.
The sensors need to be replaced.
"They keep showing that there's an obstruction," Sullo said.
The override for the controller is on the bridge's centre pier, which creates yet another problem: to reach the override, the bridge's operator has to use a boat.
"So we're looking at some changes to that," he added.
A detailed inspection last year uncovered the need for electrical upgrades as well as some general maintenance. But the structure is in good condition. Sullo anticipated it will cost $300,000 to $600,000 to make the repairs, "but we're not settled on that yet."
A much-needed new asphalt surface, repairs to curbs and waterproofing will have to wait until Base Line's backup duties are over.
"We want to avoid restricting traffic on Base Line right now at least until we have Lord Selkirk completed," Sullo said.
He noted bridges that open for marine traffic cost 50 to 100 per cent more to maintain and operate than a fixed span. A number are needed in Wallaceburg because of recreational and barge traffic. Icebreakers also need access to ensure the river flows consistently.
"Someone had said to me once that Wallaceburg is designated the most flooded community in Canada," he said.
The repairs to Base Line Bridge won't be complex; those needed for the Lord Selkirk Bridge will be, and Sullo anticipates spending $3 to $6 million on that project. The expenditure "should get the load limit lifted; it should be able to extend the life of the structure for another 20 to 30 years," he said.
Built in the 1950s, the Lord Selkirk uses riveted construction and is supported by a combination of concrete abutments and wood piers. The bridge is scheduled for refurbishment in 2018 and the municipality is currently in the design stage for that project.