Rehabilitation of the Thunderbird (Fourth Avenue) Viaduct bridge is expected to start in 2022 and cost $11.12 million, with the upgrades to strengthen the structure to support heavy vehicles.
The City of Moose Jaw’s department of engineering services hired Associated Engineering (AE) months ago to oversee the project from start to finish.
This has included acting as communication liaison with affected stakeholders, holding online and in-person public consultations, completing a detailed visual inspection and condition survey of the bridge, producing a report about the bridge’s condition, and creating a preliminary design report with drawings.
The 91-year-old viaduct is a high-use traffic corridor in Moose Jaw, which sees an average of 13,500 vehicles use the structure daily.
AE is hoping to produce the preliminary design drawings by the end of 2020 or early 2021, Bevan Harlton, director of engineering services, told city council during its Dec. 14 regular meeting. The plan is to start rehabilitation in 2022.
The condition survey report recommended four options that city hall could pursue to rehabilitate the bridge, he continued.
One option includes doing nothing to fix the bridge. This would keep the structure’s load limit under 10 tonnes; no heavy trucks, buses or emergency vehicles could cross; and it would need to be replaced in 15 years for about $35 million.
A second option is to pour a high-performance concrete (HPC) overlay, which would cost $9.5 million but not increase the bridge’s capacity. The municipality would have to apply two inches of asphalt and then maintain the bridge regularly.
The third option would allow for a reinforced HPC deck rehabilitation and see four inches of concrete poured, while a fourth option would see a reinforced HPC deck rehabilitation overlay with modification of bridge cross-sections, along with the pouring of six inches of concrete to increase the load rating for buses and trucks.
It is the fourth option that AE is recommending, Harlton said. The structure would require less maintenance throughout its life — about 50 to 60 years — while both 1.5-metre-wide sidewalks would be removed and one three-metre wide sidewalk with barrier protection would be installed, he continued.
AE held public consultations in the fall, which saw 1,465 people and stakeholders respond through a survey and virtual open house, said Harlton. Some groups included both railway companies, fire, police, the heritage advisory committee, both school divisions, and the South Hill Community Association.
“The results were consistent,” Harlton said.
People wanted to see: the heritage aspects of the bridge retained, the bridge’s weight rating increased, a safer pathway for cyclists and pedestrians, and the bridge closed completely for construction.
“I agree. It’s more safer and cost-effective (to close the bridge during construction),” he added.
Repairing this bridge is important, especially since roughly 13,500 vehicles use it daily, said Coun. Heather Eby. While it will be expensive to fix, this is a critical piece of infrastructure that needs addressing.
This rehabilitation will also be for the long-term and not simply a Band-Aid solution, she said, adding she appreciated how AE planned to include the structure’s heritage aspects.
“We know the longer you wait, the more it costs,” said Coun. Crystal Froese. “I appreciated the consultation. It was really thorough and well done and incorporated the comments people had from around the table.”
Froese also liked how the rehabilitation would allow city buses and fire trucks to cross over the bridge, while more residents would have the chance to drive over it.
The next regular council meeting is Monday, Jan. 11, 2021.
