STEVE INSKEEP, HOST:
A major route into Chicago's downtown business district is temporarily out of service. Crews are working to replace half of the historic Wells Street drawbridge. And of course half a bridge is no bridge at all. The bridge carries cars, buses, bikes and pedestrians, as well as elevated trains, prompting one Chicago official to compare its replacement to open-heart surgery.
NPR's David Schaper has a look at the operating table.
DAVID SCHAPER, BYLINE: As an engineer, Johnny Morcos loves a challenge, and as a bridge project manager for the Chicago Department of Transportation, does he ever have one. He's overseeing the replacement of the 90-year old Wells Street Bridge over the Chicago River. It's a steel truss drawbridge used by nearly a hundred thousand people a day.
JOHNNY MORCOS: It's complicated from every point of view you could possibly have. From an engineering point of view, from an urban dwelling point of view - you're in the heart of the central business district - you're cutting off CTA transit users, which there are roughly 70,000 users, and you're working over a river.
SCHAPER: Add to that Mayor Rahm Emanuel's marching orders to finish the project in just nine days.
MORCOS: And on top of that now, it's snowing in Chicago. We're in the middle of a winter storm.
SCHAPER: But despite nearly 10 inches of snow, the work continues creating a cacophony of construction.
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SCHAPER: From jackhammers breaking up bits of concrete in the steel grates of the old bridge section...
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SCHAPER: ...to the clanging of the beams that will connect the new piece of this steel truss bridge.
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SCHAPER: It all started over weekend. After the El tracks were shut down, crews lifted the north half of the drawbridge straight up into the air. A barge moved into place underneath the south half. And then steelworkers suspended on lifts from the barge, lit their torches and started cutting away.
Again project manager Johnny Morcos.
MORCOS: They were literally cutting the existing bridge free to be floated off.
SCHAPER: Crews floated that old, 500,000 pound bridge section out of the way.
MORCOS: The new section was floated in, supported on shoring towers on a barge.
SCHAPER: And, Morcos says, it's now hanging in place, while crews fasten bolts to gusset plates and beams to secure it. He says think of it liking changing a car tire.
MORCOS: What you do is you jack it up, take off the old tire, but like every owners manual says, you don't tighten that first bolt right away. You literally just hand-tighten it and then do the other four remaining bolts.
SCHAPER: Except on this bridge there are 4,000 bolts that need to be connected and secured. So crews will be working around the clock to be ready for trains, to ramble over the bridge by next Monday morning.
And despite the cold and snow, passersby can't help but stop and watch.
DAVID HAZAN: I think it's pretty awesome.
SCHAPER: David Hazan lives in a high-rise just across the river and has been photographing every stage of the project.
HAZAN: I was actually showing pictures of this to - we were at dinner with friends last weekend - and I was just like, hey, any of you that were boys and had connect sets as kids, like, tell me how cool this is.
SCHAPER: So cool, that there will be a repeat performance in late April and early May, when the north half of the Wells Street Bridge over the Chicago River will be replaced to complete the project.
David Schaper, NPR News, Chicago.
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