Tacoma Narrows Bridge

A long time ago, a bridge was built.

It was called Galloping Gertie. The bridge moved in the wind. It swayed up and down. This happened because the sides were solid. The wind could not go through them.

One day, the wind was very strong. The bridge fell into the water. No people died in the fall.

Now, there are two new bridges. They are very strong. They let the wind pass through.

These bridges help many cars cross. They stay still in the wind.

The Tacoma Narrows Bridge is a pair of twin bridges. They cross the water in Washington State. The first bridge opened in July 1940. People called it "Galloping Gertie." This was because the road moved up and down in the wind.

The bridge had solid sides. These sides did not let wind pass through. Instead, the wind caught the bridge. This made it sway and pitch. On November 7, 1940, high winds caused the bridge to collapse. It fell into the water. No people died in the fall.

Engineers learned a lot from this event. They studied how wind affects bridges. They built a new bridge in 1950. This bridge used open trusses. These are metal frames with gaps. The gaps let the wind pass through easily. This kept the bridge still. People called it "Sturdy Gertie."

In 2007, a second new bridge opened. It carries traffic going east. Together, the two bridges help many cars cross the water every day.

The Tacoma Narrows Bridge is a pair of twin suspension bridges in Washington State. These bridges cross the Tacoma Narrows strait in Pierce County. They connect the city of Tacoma with the Kitsap Peninsula. The bridges carry State Route 16 over the water. This location is very important for people traveling in the area. The bridges help many cars move between these two places every day.

How the first bridge worked is a famous lesson in science. The original bridge had solid sides made of I-beams. These solid sides did not let the wind pass through the deck. Instead, the wind would catch the bridge like a sail. This caused the road to move up and down. This movement was called aeroelastic flutter. The wind provided a steady rhythm that matched the bridge's own natural movement. This caused the bridge to sway and pitch until it collapsed.

History shows us how much we learned from the first bridge. The original span opened on July 1, 1940. It was nicknamed "Galloping Gertie" because of its odd movements. On November 7, 1940, the bridge fell into the Puget Sound. No people died in this accident, though a dog named Tubby did. Engineers like F. B. Farquharson studied the event closely. This failure helped scientists understand how wind affects big structures.

New bridges were built to fix the problem. The second bridge opened on October 14, 1950. It cost $18 million to build. It used open trusses to let the wind pass through easily. People called this new bridge "Sturdy Gertie." Later, a third bridge opened on July 16, 2007. This new eastbound bridge cost $786 million to complete. It was built to help with growing traffic on the peninsula.

Today, these bridges are part of a large twin-span complex. The 1950 and 2007 bridges are the fifth-longest suspension bridges in the United States. You can see how they work by looking at their different shapes. The older bridge used solid plates, but the newer ones use sharp edges. These edges help the wind move around the steel. This keeps the roads steady for the cars driving on them.

The Tacoma Narrows Bridge refers to a complex of twin suspension bridges in Pierce County, Washington. These structures span the Tacoma Narrows strait within Puget Sound. They serve a vital role by connecting the city of Tacoma to the Kitsap Peninsula. The bridges carry State Route 16 across the water for travelers. While the name now refers to a modern twin-span system, it is historically linked to a famous engineering failure. The story of these bridges is a fundamental lesson in how wind interacts with large structures.

The original bridge, which opened on July 1, 1940, functioned differently than modern spans. It was the first suspension bridge to use solid I-beams to support the road deck. These solid sides acted like a sail by catching the wind rather than letting it pass through. This design led to a phenomenon called aeroelastic flutter. In this process, the wind provides an external periodic frequency. This frequency matched the natural structural frequency of the bridge. As a result, the deck began to pitch and sway violently. This movement earned the bridge the nickname "Galloping Gertie."

The instability of "Galloping Gertie" reached a breaking point on November 7, 1940. Under high wind conditions, the bridge's oscillations became uncontrollable. The main span eventually collapsed into the Puget Sound at 11:00 a.m. Fortunately, there were no human deaths during this disaster. The only fatality was a Cocker Spaniel named Tubby, who was left in a car on the bridge. The collapse was captured on 16 mm Kodachrome film by Barney Elliott and Harbine Monroe. This footage is so historically significant that it was selected for preservation by the Library of Congress.

Engineers used this failure to transform the field of bridge aerodynamics. To prevent a repeat of the disaster, the successor bridge utilized a different design. This new span featured open trusses and stiffening struts. These openings allowed wind to pass through the structure instead of pushing against it. The new bridge also used steel plates with sharp entry edges. These edges help manage airflow more effectively than the flat plates used in 1940. This second bridge, nicknamed "Sturdy Gertie," opened on October 14, 1950. It cost $18 million to construct and was 5,979 feet long.

As the population on the Kitsap Peninsula grew, traffic began to exceed the capacity of the 1950 bridge. By 1990, the need for a parallel span became clear. In 1998, Washington voters approved a measure to fund a new bridge. Construction on the eastbound span began in 2002. This project was estimated to cost $849 million, but it finished under budget at $786 million. The new eastbound bridge opened on July 16, 2007. It was dedicated in honor of State Representative Ruth Fisher and State Senator Robert "Bob" Oke. The opening was celebrated with a ceremonial 5K run involving 60,000 people.

Today, the Tacoma Narrows crossing consists of two distinct spans. The 1950 bridge was reconfigured to carry westbound traffic. The 2007 bridge carries eastbound traffic. Both bridges are currently the fifth-longest suspension bridge spans in the United States. They are also ranked as the 43rd-longest in the world. To help pay for the construction of the twin span, tolls are collected from eastbound vehicles. These tolls are expected to pay off the project loans and deferred sales tax by 2033. The system uses the "Good To Go" electronic toll collection method.

The evolution of the Tacoma Narrows Bridge illustrates the relationship between physics and civil engineering. The transition from solid I-beams to open trusses shows how understanding aeroelastic fields can change how we build. The original failure boosted research into how wind affects long-span bridges. This research has influenced the design of almost every great long-span bridge built since 1940. By studying the oscillations of "Galloping Gertie," scientists learned to design structures that work with the wind rather than against it. This ensures that modern bridges remain steady and safe for the thousands of vehicles that cross them every day.