When compared to the numerous multi-million dollar construction projects currently underway in Ontario the $230,000-restoration of the historic Sneath Road Bridge in Bolton might be considered somewhat minor.
But don’t tell that to area residents, heritage preservationists and a local trail association which strived successfully to save the rivet assembly bridge from possible demolition.
Nor to the scores of spectators who turned out for the recent official reopening of the bridge as a pedestrian walkway by Dufferin-Caledon MP David Tilson and Caledon Mayor Marolyn Morrison.
The project was funded by a $140,000-grant from the federal Gas Tax Fund and an $88,000-contribution from the town. The project’s aim was to rehabilitate the bridge and make it safe for walkers without visibly altering its heritage appearance. Although there was considerable under-deck work, the railings were left untouched.
Spanning the Humber River, the bridge is designated under the Ontario Heritage Act, says former town heritage officer Heather Broadbent, whose research led to that designation in 2000 to coincide with the designation of the Humber as a Canadian heritage river.
Constructed sometime between 1910 and 1920, it was the only easterly access route into Bolton for many decades until a new road was built in the area. Now it is one of only three steel truss bridges remaining in the Humber River watershed and one of only handful in the Greater Toronto Area. But its fate was uncertain after it was closed to vehicular traffic in 2007 because of safety concerns. At one point the town’s works department made an application to demolish it, she says.
That application was vigorously opposed by the town’s own heritage advisory committee, several community groups, and a Toronto Region Conservation Authority heritage subcommittee which Broadbent co-heads.
Even the Architectural Conservancy of Ontario got involved when it arranged a site inspection by prominent civil engineer and Order of Canada recipient Roger Dorton who concluded it could be restored as pedestrian bridge at a minimal cost.
That vision was eventually accepted by the town and B. M. Ross and Associates Limited, a Goderich-based firm with considerable experience in maintaining and saving steel truss bridges, was asked to prepare a rehabilitation plan.
Although the bridge had been closed to traffic for some time it was still being used as a pedestrian crossing when it was first inspected by B.M. Ross, says project engineer Andrew Ross.
“We recommended that it be secured against all access as there was some danger of the bridge collapsing. Some of the steel floor beams were literally hanging from the deck. The bottom chord of the trusses had buckled from movement of the abutments.”
The firm urged the town to close the bridge entirely until structural repairs were made. It also outlined a program of repairs to the concrete abutments including restoration of erosion protection to stabilize them, plus the replacement of the steel deck beams and bottom chords of the trusses, says Ross.
Implementing that plan was a very selective and laborious process, says Loris Savio, project manager with Hollingworth Construction Co., the general contractor.
The first priority was to restore the abutments and that required erecting a sandbag enclosure around them and constantly pumping out the water, which was then filtered before draining naturally back into the river.
“It was a continuous operation.”
But it was the replacement of the corroded steel deck beams and bottom chords of the trusses which was the most challenging part of the project.
Using an excavator and a trolley beam, the workers hand removed approximately 75 different pieces and replaced them with news ones. This had to be done in a strict coordinated sequence spelled out in the consultant’s report, says Savio.
“We couldn’t just take out whatever piece we felt like.”
No temporary supports could be placed in the river as that would contravene conservation authority and Transport Canada regulations. So the workers attached their safety harness to two steel cables which were strung from uprights on the railings. A safety raft was also moored nearby in the event there was a collapse, says Savio.
The raft was never used. But a tarp placed under the bridge to prevent any rust flakes from the corroded components from falling into the river proved its worth.
“There was quite a bit of rust.”
Other work included reinserting the original intact wooden deck, erecting P-gates to block vehicle access, and replacing the approximately 20-foot-long asphalt approaches to the bridge with gravel walkways, says Savio.
The structural repairs returned the bridge to its original strength, says Ross. Other than closing the gap in the railings, no attempt was made to meet current Bridge Code criteria as the bridge is for pedestrian use.
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