UPEA report details condition of Lakeshore Drive deck before demolition
HOUGHTON — The thinned-out, pockmarked H-pile beam would look unexceptional in a junkyard. At its spot near the Houghton City Council dais Wednesday night, it looked out of place.
In the spot it had been for the previous 45 years, helping keep up the Lakeshore Drive parking deck, it was many similar pieces being corroded by the elements and nearing the end of their useful life — and by extension, the deck’s.
U.P. Engineers & Architects compiled a report with observations and findings from demolition of the deck. It is available on the city’s website.
UPEA’s nine-page report found the condition of the deck observed during its demolition supported the council’s decision to tear it down.
“While one cannot speculate if a catastrophic failure was imminent, the past documented safety hazards and structural deterioration witnessed during demolition provided clear evidence that failure was eventual without extensive rehabilitation of the deck structure,” the report said.
The deck was on “borrowed time,” Houghton City Manager Eric Waara said Wednesday. According to the report, decks in comparable northern climates typically have a service life of 40 to 50 years. But the deck’s expected service life had been considerably shorter.
The main culprit: deicing chemicals, particularly salt. Testing in 1999 found chloride had gotten up to 3 inches inside the decks, which in most places were only 5 inches thick. Though the city stopped using salt, the existing chloride continued penetrating the deck over the next 24 years, the report said.
The salts and moisture from the freeze-thaw cycle went through the concrete to the steel undergirding it.
About 50% of the post tensioning strands, which keep the concrete together, had lost all or most of their tension by the time the deck came down, the report said.
Many subsurface columns and steel connection plates had also corroded, the report said. Those include the H-pile unearthed during the demolition.
Crews had to stabilize the deck before tearing it down. To stop the frame from swaying, they welded large beams in place to brace the frame.
Other parts of the deck also saw damage. At the parapet walls, water infiltration had made it possible to remove the bricks by band. In the wait tower, parts of the stair pan were so corroded they fell off.
Waara had asked one of the project supervisors when it would have been easier to take the deck down, he said Wednesday. The answer: “Ten years ago.”
“It was time, and I guess this is a bit of validation for all the discussion and the debate that took place at the Planning Commission, the subcommittee, in this chamber about why we needed to take it down,” Waara said. “I know a lot of people didn’t want to take it down. I didn’t want to have to take it down. But I also didn’t want us to end up on the front page of every newspaper in the Midwest because ‘Small Michigan town suffers (insert disaster here)’. And that’s the reason why right there.”
The full report can be found at cityofhoughton.com/lakeshore-drive-redevelopment.