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Engineering Geology of the Chesapeake Bay Bridge

Carl W. A. Supp
Carl W. A. Supp
(J. E. Greiner Company, Consulting Engineers, Baltimore, Md.)
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January 01, 1957


The Chesapeake Bay Bridge, a $45,000,000 structure, dedicated July 30, 1952, extends 4.3 miles across Chesapeake Bay, linking Maryland's Western Shore with Del-marva Peninsula. Superstructure consists of simple and cantilever deck spans, 2920-foot suspension main bridge, and 1720 feet through cantilever span. Substructure is entirely on steel piles up to 135 feet long and penetrating to lowest elevation–203 feet M.S.L.

Two alternate locations were investigated by 38 borings, totaling 7372 linear feet; the deepest reached elevation–355 feet. Representative grain-size analysis, time-consolidation, Atterburg Limit, compression, and related laboratory tests on 501 ordinary and 93 undisturbed samples furnished quantitative data for substructure design. To enable three-shift drilling, and eliminate shore-based survey crews and delays during periods of restricted low-level visibility, barges were positioned by use of special sextant charts which afforded virtually instantaneous graphical fixes based on observed angles between night-lighted, elevated shore signals.

Two shore-to-shore geologic sections were developed, depicting unconsolidated Coastal Plain formations penetrated, including Recent and Pleistocene silts, sands, and gravels; the Aquia (Eocene); and the Monmouth, Matawan, and Magothy (Upper Cretaceous). Explorations of the drowned Pliocene (?) valley of the Susquehanna encountered 1.5 miles west of the Eastern Shore beneath 65-90 feet of water were of critical engineering importance and are of unique geologic interest. Former channel, approaching 5000 feet in width, bottom at elevation-170, and filled with up to 100 feet of highly compressible organic silt, necessitated use of longest piles on project.

Integrated geologic and soils studies proved exceptionally valuable in all phases of the project.

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GSA Engineering Geology Case Histories

Engineering Geology Case Histories Number 1

Parker D. Trask
Parker D. Trask
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Geological Society of America
ISBN electronic:
Publication date:
January 01, 1957



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