Tacoma, WA Tacoma Narrows Bridge Collapse, Nov 1940

tacoma_narrows_bridge_-_image_from_wikipedia.org_

Thought It Was Permanent.

“Before the bridge was completed we had a complete model of it at the University of Washington.” he added, “Our tests with that dynamic model satisfied us that the bridge would be permanent.”

Private investors hold $3,750,000 of the bridge bonds. These were sold publicly last month by a local banking syndicate and covered that part of construction costs which was not borne by the Federal Public Works Authority.

Financial experts said they believed the private bondholders would suffer little, if any, loss as a consequence of the collapse.

Prof. R. B. Van Horn of the University of Washington Engineering School at Seattle said the peculiar topography of the narrows, over which the bridge had been nicknamed Galloping Gertie by travelers because of its strange weaving motion in the wind. Some persons became seasick while walking across.

Engineers Sought Cure.

For several months engineers had been working on methods to eliminate or minimize the sway. Only a month ago attempts to take the bounce out of the bridge went awry when a twenty-three-mile-an-hour wind snapped four temporary tie-down cables from concrete blocks.

The highway bridge, generally considered an important defense project, shortened the distance from eighty to thirty miles between Fort Lewis, United States Army post near Tacoma, and the Puget Sound Navy Yard at Bremerton. The project was financed by a federal grant of $2,880,000 and an RFC loan of $3,520,000. The loans were to be repaid by tolls.

The central span was exceeded in length only by the Golden Gate bridge in San Francisco and the George Washington bridge in New York.

The broken remains of the once stately bridge presented a strange sight: the two main towers remained but were tilted toward the shore; the two main cables, more than seventeen inched in diameter, still were intact, and dozens of smaller cables dangled from the big cables; stubs of about 100 feet long jutted out toward the channel from each tower, tilting upward, and bits of railing still dangled from other cables.

The bridge was considered a triumph of engineering, not only because of its size but because of the natural hazards afforded by the strong tides which passed underneath and around the towers twice a day. Currents of eight miles an hour and a difference of twelve feet in vertical tides were frequent.

The bridge was built by the State Toll Bridge Authority, which in turn let out several contracts, the biggest going to the Pacific-General-Columbia Company, composed of the Pacific Bridge Company of San Francisco, the General, Construction Company of Seattle and the Columbia Construction Company of Bonneville.

In Washington, John W. Carmody, Federal Works Administrator, ordered PWA investigators to inquire into the cause of the collapse.

PWA officials said the federal agency, which made a $2,900,000 grant for the structure, called in outstanding engineering consultants when the bridge was built and that it had inspectors both on the job and at places where material for the bridge was produced.

Dallas Morning News, Dallas, TX 8 Nov 1940

Continued