Fabricating Mackinac Bridge towers at American Bridge Co.

Michigan's Mackinac Bridge was the longest suspension bridge in the world when it was built in the mid-1950s. The bridge was an engineering marvel and one of the American Bridge Company's greatest bridge construction projects.

American Bridge's Ambridge plant, at that time the largest structural steel fabricating plant in the world, fabricated the bridge's towers.

According to the Mackinac Bridge Authority,

The towers were fitted together horizontally at Ambridge, PA., taken apart and shipped by rail to St. Ignace (MI). The pieces were then placed on a barge and towed to the site and the creeper set them in place. This was like putting together a puzzle.

I'm not sure what phase of fabrication the photos below show. Maybe someone who knows more about this project can provide some helpful descriptions.

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

Fabrication of Mackinac Bridge towers
American Bridge Co., Ambridge
circa 1955
credit: Mackinac Bridge Authority

The plant was closed for virtually all production in mid-1982, and closed for good in the spring of 1984.