FEC Strauss Bascule Bridge: Counterweight Tower and Truss

Unless otherwise noted, all illustrations and text are copyright 1997, E W Wall.

The Counterweight Tower is a triangular truss. Span is 120 feet from main trunnion to southern floorbeam. The two northernmost panels are each 36 feet long and the two southernmost are each 24 feet long. Width of the tower is 32 feet 4 inches center-to-center of the trusses.

Height of the counterweight trunnion is 82 feet above the bottom chord. When the bridge is in the closed position, the top of the Counterweight Truss is 35 feet above and 13 feet south of the trunnion, and 117 feet above the bottom chord of the Counterweight Tower; the First Link Pins are 34 feet 7 and one-quarter inches above and 48 feet north of the trunnion; the rear of the truss is 16 feet above and 70 south of the trunnion. Width of the Counterweight Truss is 21 feet 4 inches center-to-center of the trusses. Total weight of steel and concrete in the Counterweight Truss appears to be in the neighborhood of 5,500 tons.

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Below are details of the tower. Click on the thumbnails below to see larger images.

Tower 1 Tower 2

Tower and weight All

Below are details of the Floor. Click on the thumbnails below to see larger images.

Southern pier Southern portal Northern portal Northern pier

Below are details of the Counterweight Truss. Click on the thumbnails below to see larger images.

Top of CT Entire CT Southern end of CT Northern end of CT 1st Link Pins

Below are details of the Counterweight. Click on the thumbnails below to see larger images.

Weight and truss Weight and tower Weight bracing Bottom of weight Weight, tower and strut


Motor House

The motor house is supported between the northern endposts on two horizontal postless Warren trusses extending from those endposts to the kingposts. The trusses are made of 4 angles 6 x 4 x five-eighths inch; the diagonals are each made of 2 angles 4 x 4 x three-eighths. The electric motors work pinions on either side of the motor house. The pinions in turn drive the racks on the bottoms of the operating struts. The racks and pinions mesh inside housings which rotate to accomodate the racks. Below are details of the motor house. Click on the thumbnails below to see larger images.

Front Side Back


Operating Struts

The operating struts (one on each side) are built up of 2 webs 41 1/2 x five-eighths inch, 8 angles 6 x 4 x three-eighths and 8 plates 10 x three-quarters. An additional plate of 21 x one-half finishes each strut. The struts are doubly laced at the top. Struts are 3 feet across and are 32 feet 4 inches apart (inside to inside of steel). The operating racks have 69 feet 2 and five-sixteenths of an inch travel. Below are details of the operating struts. Click on the thumbnails below to see larger images.

Struts 1 Struts 2