For years I had a recurring nightmare of traveling as a passenger in a car on a bridge impossibly high over a miles-wide river that steeply sloped down to the opposite shore. The bridge was so narrow cars could barely pass each other and as we drove over the bridge it swayed in the wind because it was old and rickety. Nobody else in the car was concerned as the bridge groaned and swayed and none of them paid attention to me as I urged the driver to turn back. As we traversed towards the other side, the bridge rocked violently side-to-side and seemed on verge of collapse. I always woke up before the bridge collapsed (so — maybe it didn’t).

My nightmare has some basis in reality: The United States has 614,387 bridges and nearly 40% are 50 years old or older. According to a 2018 report, 9.1% of our bridges are structurally deficient (bad, but an improvement from the 12.3% that were deemed deficient in 2009). According to Ray LaHood, who served as Transportation Secretary in the Obama administration, “America’s infrastructure is like a third-world country.” Given these statistics, it’s surprising that we don’t experience more bridge collapses than we do.

With that background, let’s look at some famous bridge collapses and their causes.

Tacoma Narrows Bridge

The Tacoma Narrows bridge was built in the late 1930s and opened on July 1, 1940. At just over a mile long, it was the third longest suspension bridge ever built at the time. It was intentionally designed to be the most flexible bridge ever built in order for it accommodate the stresses of spanning such a long distance in a suspension fashion.

Unfortunately, prior to the Tacoma Narrows collapse, engineers didn’t consider the aerodynamics of bridges and the effect of the wind. Here’s what happened:

On November 7, high winds buffeted the area and the bridge swayed considerably. The first failure came at about 11 a.m., when concrete dropped from the road surface. Just minutes later, a 600-foot section of the bridge broke free. By this time, the bridge was being tossed back and forth wildly. At one time, the elevation of the sidewalk on one side of the bridge was 28 feet above that of the sidewalk on the other side. Even though the bridge towers were made of strong structural carbon steel, the bridge proved no match for the violent movement, and collapsed.

Source: History.com

Check out this video of the collapse. It is mesmerizing and scary. It really gets going at about the 3 minute mark.

Big Bayou Canot

At around 3 a.m. on September 22, 1993 an Amtrak train was crossing the Big Bayou Canot bridge outside of Mobile, Alabama when it hit a kink in the tracks and derailed. The derailing caused a locomotive car to hit a bridge span and the subsequent collapse of the bridge. Three locomotives and four train cars plunged into the water and forty-seven people died. It was later determined that the kink in the tracks was caused when a tugboat ran a barge into a bridge span minutes before the accident.

Silver Bridge Collapse

Silver Bridge connected Point Pleasant, W.V. and Gallipolis, Ohio over the Ohio river. It was a gleaming suspension bridge constructed in 1928 and painted with silver aluminum paint. Here’s what it looked like prior to collapse:

On December 15, 1967, at peak rush hour, the bridge collapsed sending 31 cars with 61 people plunging into the 44 degree waters of the river. 46 of the 64 people died in the accident. The cause of the collapse was traced to a small defect in “a single eyebar — a 55-foot-long section of steel, two inches thick and 12 inches wide — had suddenly fractured. Then the pin holding it in place fell loose, sending the bridge’s components into catastrophic failure.” Source

The Silver Bridge collapse led to the National Bridge Inspection Standards which require bridges with spans over 20 feet to be inspected every two years. Here’s a post-collapse picture:

Minnesota I-35W Bridge Collapse

In 2007 the Interstate I-35W bridge over the Mississippi River in downtown Minneapolis collapsed sending cars, trucks and a school bus into the river. Thirteen people were killed and 145 were injured. The bridge had been inspected and found structurally deficient and was in the middle of structural repairs when it collapsed. The cause of the collapse has been attributed to support plates being only as half as thick as they needed to be.

Oakland’s Cypress Street Viaduct Collapse

On October 17, 1989, a powerful earthquake in the San Francisco bay area caused a double-decker bridge to collapse, killing 42 people. The viaduct was constructed in the 1950s and opened in 1957.

Hyatt Regency Walkways

The deadliest bridge collapse in U.S. history is the pedestrian walkways that were in the Hyatt Regency Hotel in Kansas City. On July 17, 1981, “the walkways on the second and fourth floor of the Hyatt Regency Hotel collapsed under the weight of guests. They then both crashed onto a crowded dance floor in the lobby.” Source.

Golden Gate Bridge

Of course, the Golden Gate Bridge has not collapsed. As a bonus though, here’s a video and commentary of my thoughts driving over it a few years ago with my friend and co-worker Liz.