Inspectors feel weight of bridge’s collapse

There are holes in the steel girders supporting state bridge K-18-R.

Not big holes. The size of a deck of cards, maybe. But the corrosion so alarmed state inspectors on a routine visit Thursday that they asked their supervisor to take a look.

Which is why he’s now perched 40 feet above the Arkansas River, bracing his back against the concrete deck of the bridge and his feet against the rust-scarred steel trusses that keep the structure up. Jeff Anderson is tapping the girders with a geologist’s pick, listening to each ping and clank for clues about how K-18-R is bearing up. He’s waiting for the bridge to talk to him.

“Watch out below!”

A very sizable chunk of corroded steel gives way under Anderson’s probing and tumbles down, shattering on the bike path that runs along the river.

Built in 1924 in this modest farm town in south-central Colorado, the bridge is one of about 75,000 nationwide deemed “structurally deficient.” Its sufficiency rating stands at 47 on a scale of 100 -- lower, by a few points, than that of Minneapolis’ Interstate 35W bridge before it collapsed into the Mississippi River on Wednesday. Anderson’s inspection could bump Pueblo’s bridge down into the low 20s on that scale.

A heavy truck passes overhead, and K-18-R wheezes like an asthmatic patient: Eeeeh-huh. Eeeeh-huh. The girders tremble under the stress. Just like they’re supposed to, Anderson says.

An engineer trained at the University of Colorado at Boulder, he designed bridges for 15 years before joining the state inspection team seven years ago. On this afternoon, he’s sweating, filthy and just a bit freaked out by all the spiders -- “I hate spiders,” he says, more often than he realizes -- but Anderson is in his element.

The air down here smells of must from the mud-drab river below. Birds flit past, whirling in shafts of sunlight. Dirty white crystals hang like icicles from the underbelly of the bridge deck; they’re almost pretty, until Anderson explains that they’re formed from mortar leaching out of the concrete, weakening the roadway.

A midweight vehicle rumbles overhead, and K-18-R squeaks insistently, a rusty-tricycle-wheel sound. Then there’s a steady, calming whir as a succession of lighter cars whiz by.

Governors in state after state have ordered emergency inspections of thousands of bridges in the wake of the Minnesota collapse.

Some teams will use high-tech equipment: ultrasound to check for cracked bolts or a special dye that can point out stress fractures. Computer modeling helps determine how much weight the bridge can bear. Magnetic particle testing evaluates the strength of welding.

Anderson, 51, prefers to use nothing more sophisticated than binoculars. He brings wading boots and climbing gear to each job (though he shimmied along this bridge with just his bare hands and his Nikes). He likes to get up close to his patients, crawl on and in and under the bridge; he makes his diagnosis by sight and sound.

Or as he puts it: “There’s a lot of intuition.”

Just now, he’s studying the report his inspectors filed the day before. They haven’t had time to type it up, so it’s just a dust-streaked page scribbled over in red ink. “Section loss W Web. R3 corrosion at abutment plate bearing. R3 R4 Stringer H.” Anderson checks each spot. There’s corrosion all right, but it’s all on the periphery of the steel truss; none of it has even begun to affect the main load-bearing girders.

He can’t understand why his inspection team flagged this bridge as critical. An overreaction to the Minneapolis tragedy, he thinks. The unexplained failure there has made some inspectors jumpy, too quick to see potential catastrophe at every weld.

Not that Anderson doesn’t recognize the potential for catastrophe.

Colorado’s 8,000-plus bridges get visual inspections every two years. Every five years, teams use ultrasound to examine key bolts and pins for cracking. Divers inspect underwater pilings every five years as well.

That regimen is up to federal code. But Anderson knows how much could happen between inspections. A truck could slam into a key support pillar. Joints could freeze up, stiffening girders that are supposed to sway as they absorb stress.

Once, late on a Friday night, he was called out to a bridge -- a major artery through Denver -- because a construction crew working nearby reported an odd slapping noise. It turned out that a connector piece had snapped and one of the two main girders supporting the bridge had broken free. The bridge was closed immediately.

So when he’s asked whether the Minneapolis collapse makes him more anxious, Anderson smiles wryly.

“I was already anxious,” he says. “I’ve seen things where, in my opinion, it was only for the grace of God that the bridge didn’t go.”

Later, he wonders whether he should have said that. He doesn’t want to give the impression, he says, that “all the guys in our office are praying every day that the bridges don’t fall down.”

So he doesn’t pray daily? “Not daily, no,” Anderson says. “Weekly, maybe.”

He’s ready to check out the other side of the bridge now, so he scrambles up to the deck to walk across.

This is a gritty part of town. Approaching the bridge from the west, you pass Discount Liquors, Discount Tires and a tumbledown shack of a store selling leather biker chaps. The east bank looks like a junkyard, though a sign advertises Top Notch Trailers.

Vehicles stream across the 280-foot bridge: a front-end loader, a gold Pontiac with kids in the back seat, a Ford Explorer with handicap plates. A Mack truck crosses with a load of scrap metal.

Anderson sometimes finds himself picturing all the people in these vehicles, all the drivers and passengers who depend on him without knowing.

Now, though, he’s focused on finding a way down under this side of the bridge.

He spots a crawl space that looks promising. All he has to do is wedge himself through an 18-inch opening, lower himself to balance on a narrow foothold and then jump a few feet so he lands on a ledge under the girders.

“We could surely make it,” he says -- and he does.

The bridge looks worse over here. A 2-foot-by-3-foot chunk of roadway has eroded badly; one layer of the steel rebar used as support has been worn away to the thickness of a telephone wire.

There’s a hole the shape of a fountain pen in one girder, and when Anderson taps at another, a cascade of flakes falls across his orange shirt. “That’s the steel,” he says.

Again, though, Anderson sees little cause for alarm. This is the type of wear and tear that gets a bridge labeled structurally deficient. But it’s all on the edges of the span; Anderson can see no significant problems in the center, which bears the most weight.

“I’ve seen bad,” he says, “and when it’s bad, it jumps out at you.” This doesn’t.

He waves toward the painted-green forest of steel. “Those things have a lot of life left in them.”

Satisfied, Anderson prepares to hoist himself back through the crawl space.

He’ll have to talk with the inspectors who wrote up this bridge.

They’ll look at digital photos and come up with a new ranking.

The bridge will continue to be listed as structurally deficient and in poor condition.

It’ll still be in line for repairs.

But it most likely won’t be flagged as a crisis, so those repairs may be years off.

In the meantime, 10,000 vehicles a day will continue to cross K-18-R.

Anderson is fine with that.

“People ask, Do you think it’s safe? I want them to know: There’s no way we would leave a bridge open that we thought was unsafe,” he says.

“Of course,” he adds, considering, “the guys in Minnesota probably would have said the same thing.”

Anderson pulls himself into the sunlight.

“That’s why I’m praying. Every week.”

stephanie.simon@latimes.com