History of the Tacoma Narrows Bridges
Previous posts in the New Narrows Bridge Series:
The First Bridge - "Galloping Gertie"
I am fortunate to live near an engineering marvel recently completed: the new Tacoma Narrows bridge. Most folks have heard of the Tacoma Narrows bridge — at least the first one, “Galloping Gertie”, which catastrophically failed during a windstorm in November 1940.
Built at the cost of $6.6 million dollars, designed by world-famous bridge architect Leon S. Moisseiff (who also helped design the Golden Gate bridge), it embraced the light, elegant design principles in vogue at the time — and was designed with complete ignorance of the aerodynamic effects of high winds on bridges. Moisseiff had inadvertently created a mile-wide airplane wing, with its light-weight narrow deck and plate-girder sides. Immediately after its opening, the bridge began to have a significant wave-like motion when any wind was present – hence its nickname, “Galloping Gertie.” It survived only 4 months after its completion, culminating in a famous catastrophic collapse.
The only casualty, fortunately, was Tubby the three-legged dog, whose owner could not wrest him from the car, to his ultimate and most unfortunate demise.
May he rest in peace.
The fallen span of the bridge remains at the bottom of the Tacoma Narrows, and has been designated a National Register of Historic Places to prevent its salvage. It became one of the world’s largest artificial reefs, and is home to a plethora of marine life, including the world’s largest octopus, the Giant Pacific Octopus.
The remaining structure was disassembled and sold for scrap during WWII. The caissons and anchors (for the cables, on either bank) were used, largely unmodified, to support the towers and cables of the second Narrows Bridge.
Below are several excellent videos detailing the construction, opening, and collapse of Galloping Gertie.
The above videos show the construction, opening day, and collapse of the first Tacoma Narrows Bridge
The Second Bridge
The second Narrows bridge was begun in 1948, its initial erection delayed by WWII, and was completed on October 14, 1950, 29 months after construction began, at a cost of $14 million. It was one of the most highly researched bridge engineering projects in history, and greatly advanced the understanding of aerodynamics in suspension bridge construction. A 1:72 replica of both the original and the new bridge were built in a wind tunnel and thoroughly tested for several years prior to design completion.
Designed to carry 60,000 cars per day, the second bridge ended up ferrying over 90,000, and had become a major choke point for traffic in the rapidly growing South Puget Sound area. These transportation pressures gave rise to the new Tacoma Narrows Bridge project.
The New Tacoma Narrows Bridge Project
The Tacoma Narrows is a formidable natural barrier. Carved out by ancient glaciers, over a mile wide and 260 feet deep, with steep, unstable banks on either side, it is a challenging environment for a suspension bridge. Wild tidal currents rip through the Narrows twice daily, through the sole portal between the Pacific Ocean and the entire South Puget Sound. High winds and fog are common. The Puget Sound area is also prone to major earthquakes.
The new Narrows Bridge project was the largest engineering endeavor in the U.S. in the last 30 years. Construction began in late 2002, after approval of an $800 million public-private financing package.
Next: It’s time to look at the foundations: The bridge cassions.
