The New Clark Bridge: Saddle-Draped Cables

by David Goodyear, Pres.; DGES, Inc., 2639 Parkmont Lane, Suite B, Olympia, WA 98502.,
Ralph Salamie, Project Manager; McCarthy Brothers, 1341 N. Rock Hill Rd., St. Louis, MO 63124.,

Serial Information: Civil Engineering—ASCE, 1994, Vol. 64, Issue 8, Pg. 46-49

Document Type: Feature article


The new $85 million, 108 ft wide Clark-Bridge replaces a 20 ft wide 1928 truss bridge at Alton, Ill., carrying US 67 over the Mississippi about one mile above the recently completed Lock and Dam 26. There are two traffic lanes in each direction, plus shoulders and a 10 ft wide median. The three-span, 1,360 ft cable-stayed section, bid for $34.9 million, was erected without the serious problems that have plagued similar structures despite some unique features such as being the first in the U.S. where such a light steel framed cable-stayed design was combined with a cable saddle type of pylon. Each of two pylons is a single 283 ft tall mast located on the roadway centerline, similar to the Sunshine Skyway except that 22 cables, continuous from edge to edge, are draped over a saddle atop each pylon. Prior to grouting, the cables were restrained at the pylon head only by friction. This required four stay jacks working simultaneously at each installation and adjustment operation. Even though the incomplete bridge withstood the raging force of the Mississippi with no damage during the 1993 flood, construction was delayed for two months when the Corps of Engineers shut down all barge traffic including the contractor's. The conventional steel girder approaches were bid and erected separately. Work began in July 1991 and dedication took place in January 1994.

Subject Headings: Cables | Cable stayed bridges | Truss bridges | Traffic delay | Steel structures | Locks (dam) | Infrastructure construction

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