Winter 2010-2011 Michigan Tech Magazine

A Crown for the Mighty Mac

By Marcia Goodrich
It is 1970 or so. Six-year-old Tess, her sister and two brothers, and their pet wiener dog are packed into the family station wagon, with a borrowed travel trailer bouncing along behind. It's the first day of vacation, and the Carbary family has been on the road for four hours since leaving their Bay City home, a pretty long haul in those days.

The weather is cool, gray, and foggy, as summer days once were in Northern Michigan. Dad pulls into a small roadside park, so the dog can do her business and the bickering kids, all bundled in sweatshirts, can stretch their legs. Next, they'll head over for a quick meal at a drive-in in Mackinaw City and then set up camp.

Tess loves vacation, and she loves camping, and she wishes they would just go straight to the campground instead of wasting time in this dumb park. Then, as she clambers out of the back seat, she slows. She inhales the primal air of the Mackinac Straits, and a breeze ruffles her fluffy red hair.

The mist rises like a curtain, and the sky brightens to turquoise over deep blue water. Suddenly Tess is looking at the most wonderful thing she has ever seen. Minutes later, she vaguely hears her mother calling, "Theresa, get in the car, we're ready to go," but she can't move. All she can do is stand in the little park and stare at the Mackinac Bridge.

The Carbarys didn't actually cross the bridge between Michigan's upper and lower peninsulas on that vacation. Their first time for that came six years later on a family trip to Copper Harbor. Again, Tess was dazzled by the bridge and this time fascinated by an engineering school they passed on their way to the tip of the Keweenaw. She got her first chance to actually drive over the Mighty Mac herself while heading to orientation at Michigan Tech, where she would major in (what else?) civil engineering. "I came up with a high school friend," says Tess (Carbary) Ahlborn, now an associate professor. "I remember my friend and me and my baby blue Chevette. The bridge was so overwhelming."

Since then, Ahlborn has crossed the Straits countless times, on visits home and on University business, and she has never stopped loving the Mackinac Bridge. So, when Tom Maxwell '86, an old friend from college, asked her if she would help nominate it for recognition as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers (ASCE), she said yes in a heartbeat. "I was so honored," she says. "The bridge is just magnificent. It's a marvel."

"About two years ago, ASCE National asked us to submit a nomination on behalf of the bridge, and they suggested we work with Tech," says Maxwell. "At the time, I was president of the ASCE Michigan Section, and I knew Tess was a structural professor at Tech. When I asked her, she said, 'I'm on it,' and she and a grad student put it together in about four months."

"They did a great job," he says. "It was a wonderful thing to do on behalf of the state and the Mackinac Bridge Authority."

Ahlborn's nomination provides an overview of the bridge's construction (it took three years and cost nearly $100 million), its historical significance (fulfilling a 1888 dream for an easy crossing of the Straits of Mackinac), and its unprecedented features (allowing it to withstand wintry ice and gales).

In particular, the Mighty Mac put to rest concerns raised by another suspension bridge, the Tacoma Narrows in Washington state. "Gallopin' Gertie" collapsed under 40 mph winds in 1940. In designing the Mackinac, lead engineer David Steinman introduced new design elements, including a framework of steel girders reinforcing its entire length. His aerodynamic studies showed that the Mackinac Bridge would be able to withstand winds in excess of 600 mph.

In August 2010, when the ASCE officially designated the bridge as an Historic Civil Engineering Landmark, it became the 251st structure to earn the title. ASCE President-elect Kathy Caldwell listed a few of the others when she spoke at the dedication ceremony, held August 12 at Bridge View Park in St. Ignace. The Mackinac Bridge was joining the ranks of the Panama Canal, the Eiffel Tower, the Statue of Liberty, and the Brooklyn Bridge. "Steinman built four hundred bridges around the world, and he called the Mackinac his masterwork, the greatest of all,'" Caldwell said.

The bridge was more than a masterwork when it was completed in 1957. It was a godsend. Previously, motorists had to rely on ferries, and sixteen-mile backups were common, Gerrad Godley, president of the ASCE Michigan Section, told the crowd at the dedication. And anyone traveling between the peninsulas had to time their arrival in the Straits; otherwise, they could find themselves spending the night in their cars, waiting for the first ferry to leave in the morning.

Nevertheless, the challenges of building a five-mile bridge in such an extreme environment delayed construction until 1954. When it opened for traffic, the so-called "bridge that couldn't be built" was the world's longest suspension bridge between cable anchorages. At the dedication, Bob Sweeney, chair of the Mackinac Bridge Authority, called the bridge "an example of what happens when engineers seek to do the impossible."

"When the Mighty Mac was completed and opened up to traffic, it changed the dialogue about what was possible with suspension bridges," said State Transportation Director Kirk Steudle. "It was built in the worst possible conditions," he said, "and, obviously, it was very well built."

After the ceremonies, Bridge Engineer Kim Nowak '85 could not have been happier. "It is really exciting to be recognized on this level," she said. Then, without a lick of exaggeration, she added, "I have the coolest job in the state."

As if to prove it, Nowak hosted Maxwell, Ahlborn, and a handful of others for a bridge tour. "And the next thing I knew, we were on top of the south tower," said Ahlborn. "I thought, 'This is unbelievable!' Ever since I was a little girl, I always wanted to know what it looked like from the top, and now I know. It's fantastic."