Beautiful Mackinac Bridge
The Mighty Mackinac Bridge
25th Anniversary
(This article is from the
July 1983 issue of "The Ironworker" magazine)
For the first 150 years since being organized as a territory,
in 1805, the state of Michigan was divided into two separate peninsulas. The southern portion contained the motor city
of Detroit, the capital city of Lansing and most of Michigan's big cities. The northern peninsula bordering
Lake Superior, was iron country--Ironwood, Iron Mountain, Iron River--and stretched from the northern tip
of Wisconsin eastward to Canada and Sault Ste Marie.
Up to a little over a quarter century ago, the only way to get across
the Straits of Mackinac was an hour long ferry boat trip. During bad weather, forget it. And during vacation
and hunting seasons, you could wait anywhere from two to six hours just
to get onto the ferry.
Now, with the mighty Mackinac Bridge, close to two million vehicles
cross the Strait in about 10 minutes in all kinds of weather, and the two peninsulas of Michigan are now joined
by an engineering feat which, 25 years ago astounded all but the Ironworkers who built the big bridge.
A hundred years ago, when the Brooklyn Bridge was opened, (see May issue)
newspaper ads appeared: "A Glimpse of the Future--Proposed Bridge Across the Straits of Mackinac."
Fifty years ago, with the opening of the Golden Gate Bridge (see April issue), plans were drawn for the
Mackinac Bridge and a causeway was built on the north side of the straits, but it wasn't until 30 years ago
the bonds were sold and the contract for $99,800,000 was bid by American Bridge Company. On June 28, 1958, the
Mackinac Bridge was dedicated.
Until the Verrazano Narrows Bridge was built in 1965 in Lower New York
Bay the Mackinac Bridge people liked to think that theirs was the largest suspension bridge in the
world. While its main span measures 3,800 feet to the Golden Gates 4,200, from main anchorages it measures 8,344
feet (to the Gates 6,450) and five miles long if you include approaches.
Regardless of how the Mackinac Bridge is measured, it is massive. A
million tons of concrete and steel went into the massive piers and anchorages,
three-fourths of them underwater. Although some geologists said no structure could withstand the force o storms and ice pressure at the Straits,
the concrete of the piers and anchorages are protected by interlocking steel
caissons, sheet piling and wrought iron
plate. Working off a solid set of foundations, the Michigan Ironworkers then
had to produce acrodynamic stability for the for the suspension. Stiffening trusses 38 feet deep and 10 feet beyond
each side of the roadway prevent the kind of sway which brought down the Tacoma Narrows Bridge in 1940.
The next step was to "spin the cables," but that's a misnomer because
the 12,580 wires of the cable were placed parallel, not twisted or braided.
Working along two catwalks anywhere from 190 to 500 feet above the water, he next step was to "spin the cables," but that's a misnomer because
the 12,580 wires of the cable were placed parallel, not twisted or braided.
Working along two catwalks anywhere from 190 to 500 feet above the water, Ironworkers compressed and clamped the 37 strands of 340 wires into
cables thicker than an oil barrel, and more than two feet in diameter before winter closed in.
One by one, counterbalancing each pier, stiffening truss restraints
were raised and connected to suspenders off the huge cables and the connectors. Within one month, Ironworkers welded
more than a million connections to attach the open grating to the bridges floor beams, for the center lanes.
Just a day or two before the bridge opened, asphalt went down over the
rebar and lightweight concrete on the outside lanes. And then Michigan's
two peninsulas were joined.
The Mackinac ferry system of five boats handling a maximum of 416 vehicles
an hour was overnight replaced with a new bridge capable of handling 6,000
vehicles per hour. The Mackinac Bridge connects Mackinaw City on the south with St. Ignace,
named after the founder of the missionaries which settled there in 1671.
Jesuit Father Jacques Marquette is buried there, where the waters of Lake Michigan run into Lake Huron.
Chippewa Indians for centuries lived north of the straits; the Ottawa
Indians on the south. But the Algonquin named the straits Mechilimackinac
which means great road of departure, or in common vernacular, the end of
the road. But not anymore, until the Mighty Mackinac Bridge. The motto of Michigan is "Si quaeric peninsulam amoenam circumspice,
"or, if you seek a pleasant peninsula, look around you." Atop the mighty
Mackinac Bridge, Ironworkers could see not one but two pleasant peninsulas,
soon to be linked.
Love that bridge, can't leave it
One Ironworker who hired on with the bridge crew at Mackinac loved the bridge so much he sunk his roots in Mackinaw City. After topping out the bridge, J.C.Stilwell, a member of Local 340 Battle Creek, opened a motel south of the city and then a pizza parlor at the foot of the bridge. Over the years he collected mementoes of the bridge construction and last year opened the Mackinaw Bridge Museum above his restaurant. It remains open free of charge to the public.
A few weeks ago J.C. shut the museum down for the day and in a "consulting staff" of fellow Ironworkers who had worked a quarter of a century ago on the Mackinac. These 14 bridgemen studied the artifacts in the museum and swayed stories until 3 a.m. This summer the curator of the museum at Michigan State University will start to redesign the museum and add some displays this winter to commemorate the Ironworkers who built the bridge across the straits.