Spinning into history

If you didn't know better, you'd think a circus was coming to town.

Over the past three months, the new Tacoma Narrows bridge has been transformed from a gritty construction site into what looks like a place you might want to buy tickets and take the kids on the weekend.

At the east end, red and green spools whirl around a steel tower that looks as if it could be the makings of the Mad Mouse. Big green wheels dart across the water on a festive array of cables and pulleys. A lighted walkway drapes across the tower tops like a midway.

What's actually happening at the bridge is more remarkable than any amusement park.

On Thursday, crews began installing the new bridge's main cables, the two massive lines that eventually will support the 40 millon-pound bridge deck. Cables that beefy are impossible to lift into place, so the bridge builder is fabricating them strand by strand, using wire about the diameter of a pencil.

Over the next three months, Tacoma Narrows Constructors will send 19,000 miles of wire back and forth across the towers - enough to encircle the continental United States twice - and then compress it into two 20 1/2-inch-in-diameter cables.

Aerial spinning of suspension bridge cables is one of the most highly refined processes in the world of construction, but the apparatus it requires looks as if it might have been designed by Rube Goldberg.

The assemblage of spinning wheels, cables and pulleys adorning the bridge combines features of sewing machines, fishing reels and ski lifts.

No wonder it's slowing traffic.

Drivers who dare tear their eyes from traffic on the adjacent 1950 bridge are rewarded with tantalizing glimpses of mysterious spinning wheels and tiny figures clamoring around on the rigging like acrobats.

Dave Climie, the TNC engineer in charge of the spinning operation, acknowledges the spectacle is a distraction.

"We've definitely got the 'wow' factor going on," he said.

Early ideas about erecting some sort of visual barrier to keep drivers focused on the road were discarded as too impractical. (And, bridge enthusiasts might add, too cruel.)

Suspension bridges of this magnitude are a rarity in the United States. One was completed across the San Francisco Bay Area's Carquinez Strait last year, but before that, none had been built in America since the Verrazano-Narrows in 1964.

For an entire generation of American construction engineers, aerial cable spinning is a lost art. Neither Bechtel nor Kiewit, the two American-based construction giants who joined forces to form TNC, has built a suspension bridge of this size before.

Not surprising then that TNC has such an international cast.

The project's general manager, Manuel Rondòn, is a Venezuelan who learned about suspension bridges in Portugal. Climie is a Scot and has worked on bridges all over the world. Karsten Baltzer, Climie's right-hand man, is a Dane who worked with Climie on bridges in Denmark and China.

In addition, TNC is being advised on the spinning operation by a team of six Japanese engineers on loan from its subcontractors, Nippon Steel Corp. and Kawada Industries. They've been living in Gig Harbor since March, helping crunch numbers, set up equipment and train workers.

Old process goes high-tech

The basic process of spinning bridge cables has not changed since the 19th century.

But it's been refined by the computer age. The old-fashioned pulleys and wheels from the era of John Roebling, the builder of New York's Brooklyn Bridge, now are guided by computers and GPS locating equipment.

The result will be a structure of geologic proportion built with the precision of a Swiss watch.

When completed, the two main cables each will be more than a mile long and weigh more than 5 million pounds. Yet the height of the cables in the center of the long swag between the towers must be accurate to within half an inch.

The spinning process is as fascinating to the lucky few ironworkers and equipment operators chosen to work on it as it is to the commuters eyeballing it from the existing bridge.

Twenty-eight workers per shift, most of them ironworkers from the local union, are on the bridge during spinning, spread out in predetermined positions along the catwalks, at the anchorages and at the tower tops.

They'll work around the clock for three months. Two crews work daytime shifts, guiding the spinning wheels on their trips back and forth across the Narrows. A third crew will work at night, adjusting finished strands to precise specifications.

Fine adjustments of the strands are done at night to avoid the radiant heat of the sun. The heat causes the steel in the towers and cables to expand unevenly, making precise measurements impossible.

"When the sun is shining the whole towers rotate," Baltzer said. "On a warm summer day you can see that the wires are rotating. Everything on top of the tower is moving around."

Before the actual spinning began Thursday, the teams of ironworkers and equipment operators who are laying in the cable puzzled over their new jobs like athletes being introduced to a new, complicated sport.

They took classes, got their sea legs on the steeply inclined catwalk and stared up at the tram haul lines, trying to visualize exactly how the process would work once the operation began.

"There's a lot of moving parts with this," said Dan "Mad Dog" Maddux, a foreman of the crew of workers handling the operation from the Gig Harbor anchorage to the middle of the span.

Maddux, a thoughtful man with wild hair and full beard, has been with the bridge project since November 2003. A Fairbanks, Alaska, native, he spent the last two winters running crews on the massive underwater caissons and towers that will support the cables.

The caisson work was more physically demanding, Maddux said. Spinning the cables takes more brain work.

"This is more complicated and there's more parts to figure out," he said. "It's going to take constant attention."

Every strand of wire has a precise position, Maddux noted. At top speed, the spinning wheels whiz over the catwalks at 40 miles an hour, an awesome clip if you're not sure what you're doing.

"It's fun, but it's stressful," said Dan Cox, a winch operator stationed on top of the Gig Harbor anchorage during spinning.

Last week, preparing for the first set of wires to come across, Cox began his shift on top of the 510-foot Gig Harbor tower.

Below him, 12-foot-wide mesh catwalks receded to points as they dropped away through empty space. Above, steel cables as thick as Cox's wrist mysteriously started and stopped, running over a wheeled apparatus resembling the running gear of a railroad locomotive.

"It's like making a spider web or a spun glass sculpture," Cox said. "Everything has to be tensioned just right or the whole thing fails."

Cox said his duties on the winch demand such attention that his eight-hour shift passes in the blink of an eye. His attention is sharpened, he said, by the knowledge that a wrong move could have disastrous consequences.

"There's pinch points all over this bridge," he said. "Your ultimate nightmare is to kill or injure someone."

Spinning across the narrows

The spinning operation is simple once you see it, but visualizing it in the abstract takes considerable imagination.

The center of operations is in the "control cabin," a steel box with bars over the windows, set up near the Tacoma anchorage. The bars, there to protect operators from cables that might break loose under tension, give the cabin the look of a portable jail.

Inside, it is packed with an array of control panels and dials. As T.J. Paul, one of the operators, put it, "It looks like 1964 NASA."

From inside the control cabin, Paul controls the movement of the spinning wheels as they travel back and forth on loops of heavy cable similar to the tramways that carry gondolas on ski lifts.

He also controls the backstage operation that keeps the spinners supplied with wire.

Thousands of coils, each containing about four miles of wire, are stacked like doughnuts on the blacktop. Crews feed these coils into the process by first rewinding them onto larger drums, 7 1/2 feet tall, like winding fishing line onto a reel.

Each drum takes six coils of wire, or about 24 miles. The coil ends are spliced together with steel ferrules, which will eventually make each cable a single continuous strand.

Wire from drums set up behind the Tacoma anchorage is looped over a large pulley, or "spinning wheel" attached to a haul line and sent on the tram toward Gig Harbor. As the wheel goes, it draws wire off the drum, like a trout running line out of fishing reel.

Powered by the haul line, the wheel carries the wire up over the Tacoma tower top, down the big catenary across the midspan, back up over the Gig Harbor tower and into the Gig Harbor anchorage.

Workers positioned along the way make sure the wires are in their proper positions by placing them in organizers that look like upturned pitchforks.

The process can be controlled manually, but when all goes well, it travels automatically, speeding up on the downhill runs, slowing at the tower tops and pausing inside each anchorage. Each one-way trip takes between 11 and 12 minutes.

In the anchorages, workers "dog off" the wire - that is, loop it over semicircular "strand shoes," encased in concrete. Then the wheel heads back to Tacoma, picks up another loop and starts over again. And again, and again.

Bracing for unfriendly weather

That's the cartoon version. In reality, the process is more complicated because, instead of just a single loop of wire, the spinning wheels are built to handle four loops at once, drawing wire off four drums simultaneously.

The four wires are marked every 20 feet with red, yellow, green or black color coding to help workers tell them apart, but there's still plenty of room for human error.

"There's a steep learning curve," Climie said. "That's the way it is with superstructure work in general. As soon as everybody gets it, then it's on to something else.

"The first two weeks is the steepest part of the curve, getting everything set and ready," he said. "Then we try each day to do a little more than we did the previous day."

Climie said he expects the spinning operation to take three months. In the first half of that time, he said, he expects just 25 percent of the work to be accomplished.

In the second half, when the bugs have been worked out of the machines and the crews are working smoothly and efficiently, they'll do the remaining 75 percent.

Unfortunately, the three-month period allotted for the spinning operation coincides with the Northwest's worst winter weather. The notorious Narrows wind is famous for sending horizontal sleet and rain whipping through the passage.

Concerns that high winds might push the new cable work into the existing bridge led design engineers to connect the catwalks with nine stabilizing crosswalks, about twice the number normally used.

For workers, positions on the catwalk that have been indescribably pleasant on recent sunny days will become hypothermic hell when the weather turns bad.

"It's going to be tough duty out there," Mad Dog Maddux said, speaking from two previous winters' experience on the bridge. "But we'll get it done."

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Rob Carson: 253-597-8693

rob.carson@thenewstribune.com