Replacing 91-year-old double-decker Wells Street Bridge: ‘Very cool stuff’
By ROSALIND ROSSI Transportation Reporter email@example.com; @rosalindrossi April 26, 2013 7:34PM
Kevin Becker,(left) assistant project manager and Dave Tipton, Jr. foreman of Wells Street bridge project, Wednesday, April 24, 2013. | John H. White~Sun-Times
Updated: May 29, 2013 7:45AM
“I want to cut it.”
“No, I want to cut it!’’
That was the argument among ironworkers last month as they lobbied to be the torch-wielder who would make the last, critical cut needed to loosen nearly half of the 91-year-old Wells Street Bridge and send it off to the scrap heap.
“It was like brothers arguing for the last piece of candy,” Dave Tipton Jr., a joint-venture general foreman on the project, recalled of the special moment March 2.
“We had guys arguing over who was going to cut the bridge loose because we take pride in what we do. We call it, ‘old glory.’”
The argument could become even more passionate as workers prepare to cut the second and final half of the double-decker Wells Street Bridge free this weekend to make way for a new — and safer — replacement.
Several elements of the Wells Street Bridge Reconstruction Project make it an unusual architectural challenge, engineering experts say.
Those include the size of old sections to be cut away by ironworkers, the tricky insertion of a new bridge leaf into an old bridge while literally working on water and the very nature of the bridge itself .
Plus, to minimize the impact on up to 77,000 daily CTA L riders, the bridge had to be replaced over two nine-day periods — perhaps the biggest challenge of all, city officials say. The winning bid, by Walsh Construction/II in One Joint Venture, offered an efficient solution to the problem, they say.
To the average Joe, the $41 million Wells Street Bridge project may not seem as groundbreaking as the reversal of the Chicago River. But it’s “impressive” and “innovative” in its own right, said Joseph Schofer, director of Northwestern University’s Infrastructure Technology Institute.
Put simply, said Schofer, it’s “very cool stuff.’’
The Wells Street Bridge that dates to 1922 is one of 37 so-called “fixed trunion bascule’’ bridges that grace the Chicago River.
Chicago is home to more such bridges than anywhere in the world. The model has been so perfected here that it is often called the “Chicago bascule.’’
The bordeaux-colored bridges standing sentry along the Chicago River function like double-leaved drawbridges that open in the middle. They operate via a unique set of counterbalances, using the same principles as a teeter-totter.
The balancing mechanism that allows the bridges to open and close is so sensitive that a mere paint job requires its recalibration.
However, the Wells Street Bridge is one of only two double-decker bascule bridges that carry CTA elevated trains on the top deck and pedestrian and car traffic on the bottom one. That double function makes the bridge unusually heavy.
After 91 years of pounding use, the bottom horizontal chord of the bridge had become so deteriorated it was literally pocked with holes, Chicago Department of Transportation officials say.
“There was section loss. There were holes in the members,’’ said Johnny Morcos, Wells Street Bridge project manager for CDOT. “Rust can be repaired with paint but holes is a much more extensive problem.’’
More than 80 percent of the bridge — a 150-foot span in the middle — needed to be replaced, Morcos said. The 15-feet remaining on each bank of the Chicago River, he said, was strong enough to merely be repaired.
“One Big Swoop”
A critical question was how to quickly get rid of the 83 percent of the bridge that needed replacement. Cranes couldn’t be used to pull away cut-out sections of the bridge, piece by piece, because it would take too long, Morcos said.
Walsh/II in One Joint Venture proposed something much swifter.
Working one leaf at a time, it suggested placing a barge under the 500,000-pound ailing section of the bridge, stacking the barge with metal shipping containers until they fit snugly under the old bridge, and then cutting away the deteriorated section so it could be carried off in one massive chunk.
To ensure the bridge was tightly supported throughout the dismemberment process, last month workmen pumped water out of the barge to stop it from sinking even slightly as the shipping containers bore increasing amounts of bridge weight.
“It was right up against it,’’ Morcos said. “There was no gap in-between during the whole time cutting it.’’
Rather than a death by a thousand cuts, it took a mere six slices with a spark-spewing. 8-foot-long, oxygen-fed lance rod — a jazzed-up blow torch — to free the first 500,000-pound middle bridge section last month.
“They took it out in one big swoop,’’ Morcos said. “We thought it was a very unique solution. It was the tight window that made them think outside the box.’’
4,000 Bolt Holes
Perhaps the most nerve-wracking part of the round-the-clock project involves attaching the new 75-foot section of the bridge to the existing 15-feet at the river bank.
“Now you have new steel and repaired steel and if you have any fluctuation in the river level, you could damage the new steel,’’ Morcos said.
Some 4,000 bolt holes in the old section have to line up within 1/16th of an inch with a similar number of bolt holes in the new section.
Last month, a tugboat pulled the barge holding the new section over to the old section, and shoring towers with hydraulic lifts moved the new section up and down until it could be precisely threaded into the old one.
The work meant toiling outside on the Wells Street Bridge project in 12-hour shifts including weekends, at times facing sub-freezing temperatures while suspended 17 feet above the Chicago River in manlift baskets
To many ironworkers it was actually a plum assignment.
Nick Gaik, 36, was peeved that he was tied up on another ironworker job when the south leaf of the Wells Street Bridge was replaced last month. He admits he’s lobbied to get a piece of this month’s bridge work. It’s an ironworker’s dream, he said.
“It’s in my blood,’’ said Gaik. “It’s something I live for. I love this stuff.’’
And it wasn’t just ironworkers who were fascinated.
Last month’s replacement of the south leaf of the bridge attracted engineering enthusiasts, amateur photographers and even suburbanites out to watch a piece of Chicago history.
On Friday, at 10 p.m., the entire process was scheduled to begin all over again, this time focused on the north leaf.
The climatic final cuts to the existing ailing bridge are slated for Saturday afternoon and another high-tension moment — the insertion of the new bridge into the old one — should start Monday and continue into Tuesday.
“A Grand Tradition”
Across the country, bridges are aging and in sore need of repair, often requiring quick switch-outs under demanding conditions.
Although bridge replacements are occurring every day, few are like this one, said Gongkang cq Fu, chairman of the civil, architectural and environmental engineering department at the Illinois Institute of Technology.
Double-decker bascule bridges are rare, the weight of the replacement pieces is unusual and the time frame for the job is tight, Fu said.
And, Fu said, “I can’t imagine how you can line up 4,000 holes. You’re talking about holes in steel pieces that are not easy to bend.’’
Said Fu: “It is challenging. I have no doubt about it.’’
While the old bridge floats off to the scrap heap, its replacement by a new bridge has dazzled even some Chicago historians.
“It’s an impressive project like I’ve never seen before,’’ said Tim Samuelson, historian for the Chicago Department of Cultural Affairs and Special Events. “[It’s] a lot like modern microsurgery, except they are doing it with steel and blowtorches. . . .
“Chicago has a tradition of doing gutsy, adventurous engineering feats. This comes out of a grand tradition.’’