Tower caisson for the Mackinac Bridge (9 of 45)

Photo shows the cutting edge of the tower caisson No. 19 during fabrication at Alpena, MI.  Designed to work like a cookie cutter this caisson is filled with aggregate in the double wall area which acts as weight to drive it through the overburden.  The material inside the ring is removed by crane and clam bucket.  This removal relieves the pressure and the cutting edge continues to drive down until it reaches bedrock.  When positioned the whole thing is filled with aggregate and grouted to make it one solid mass., Electronic reproduction of photograph.  The Mackinac Bridge 1954 - 1958. Mackinac Bridge Authority
Abstract/Description: Photo shows the cutting edge of the tower caisson No. 19 during fabrication at Alpena, MI. Designed to work like a cookie cutter this caisson is filled with aggregate in the double wall area which acts as weight to drive it through the overburden. The material inside the ring is removed by crane and clam bucket. This removal relieves the pressure and the cutting edge continues to drive down until it reaches bedrock. When positioned the whole thing is filled with aggregate and grouted to make it one solid mass.
Subject(s): Bridges--Design and construction
St. Ignace (Mich.)
Mackinaw City (Mich.)
Mackinac Bridge (Mich.)
Date Created: 1954 (approximate)