The Tacoma Narrows Bridge

Tacoma Narrows Bridge, August, 2015

Tacoma Narrows Bridge, August, 1940

The history of the Tacoma Narrows Bridge is available online, but let me tell you about it in my own words and share my experiences with you.  I’ll share some of my photos with you, too.  Most of the photos here were taken by me from my boat or from shore or were taken by friends of mine from their boats (none of us took the 1940 photo above however!).

Let’s start at the beginning, shall we?

Back in 1940 when this bridge was built, it was dubbed “Galloping Gertie” for a darned good reason and you will soon see why.

At the time of its construction in 1940, the Tacoma Narrows Bridge was the third longest suspension bridge in the world and it was famous for that.  The height of the bridge, from the water below the bridge up to the underside of the bridge, was almost 200 feet.  The single center span alone was about 2,800 feet long, over half a mile!  The total length of the bridge was 5,939 feet, more than a mile long.

The bridge spans a waterway in Puget Sound known as “the Narrows”.  That waterway runs north/south, separating Tacoma and the Kitsap Peninsula.  The waterway is about a mile wide, so not at all narrow as far as boat traffic is concerned.  But “the Narrows” is called “narrow” because it’s the only path for saltwater to travel into and out of the very large southern parts of Puget Sound as the tide ebbs and flows twice a day.  Current (the lateral motion/speed of the water) in “the Narrows” can reach 6.5 knots (about 7.5 mph).  If your boat goes only 6 or 7 knots (about the speed that most recreational sailboats travel), and the current and tide are running against you, you’ll be going full speed but you will be staring at the same tree on shore for about an hour or two.  Best to time your passage so you are running with the current and then you will zip through lickety split.

Workers/inspectors on the bridge in 2010.

From the onset of construction of the bridge’s center-span, bridge workers could feel unnatural movement in the bridge; they are the ones who named the bridge “Galloping Gertie” because the swaying motion was so pronounced.  At first, the thought was that the water currents were causing the bridge to shake.  The water did do that, and still does, but that’s not what was causing the inordinate swaying motion.  No one addressed the issue … they simply opened the bridge to the public.

Just four months after the bridge was opened to the public, the bridge dramatically and suddenly collapsed into Puget Sound.  The bridge was now famous yet again, for all the wrong reasons.

Now it was famous for its spectacular collapse.  But the bridge became even more famous yet, after the collapse, because engineers were able to determine the cause of the collapse and then engineers worldwide changed the way suspension bridges were built and changed the types of materials with which those bridges were built.

Let’s go back to the very day of the collapse …

Barney Elliott was a local fellow in Tacoma who happened to be at one end of the bridge with his 16mm “motion picture camera”.  He took a 16mm film movie of the collapse of the bridge.  The film was saved and digitized.  Here’s the digitized edition of the original film.  (Music has been added; you might want to turn your sound off.)

Here’s another video (below) that shows scenes from the construction of the bridge, and then shows parts of Barney’s film of the collapse of the bridge.

Did you notice the guy walking along the wire without being hooked onto anything for safety?  That sure wouldn’t be allowed today, but that’s how they did it back then.

When the bridge collapsed in 1940, one life was lost … Tubby the dog.  The owner of the last car on the bridge (and he was also the owner of the dog) had stopped his car mid-span, left his dog in the car, and had run for his life (maybe “wobbled” for his life would be a better description because of the motion of the bridge by then).  Another man went back out onto the bridge to get the dog out of the car, but the dog bit him so he left the dog in the car and walked back to land.  The car and the dog fell when the bridge fell.

All very interesting, but the big question of the day was …

What happened?  Why did a brand new and so strongly built bridge collapse?  The short answer is two-fold.  Instead of open trusses, the bridge was built with solid steel beams that did not allow wind to pass through them.  As well, the edges of the beams and other parts of the structure were sharply square-cut (instead of angled or rounded).  Those flat/square-cut beams created more turbulence and resistance to the wind, which meant the wind pounded against the beams and the sides of the bridge with full force.

The wind that day was only 40mph, not particularly bad.  But it certainly was enough to wreak havoc.  Details of the structural vibration, resonance, and other forces that rather quickly took the bridge down can be read in a Wikipedia article HERE.

Reconstruction of the bridge was delayed by WWII.  In time, reconstruction was completed using new techniques and materials; the bridge re-opened in 1950.  That 1950 bridge is still in use today and is absolutely safe and sound.  I’ve driven over the 1950 Tacoma Narrows Bridge (in my car) and have been under the 1950 Tacoma Narrows Bridge (in my boat) many, many times.  The bridge is rock solid.  It sways when needed in high winds, but now it is built to allow the wind to swirl around and past the steel beams and trusses.

Three classic cruisers heading south in 2007 … my Pied Piper (1940) is on the left.
[Thank you Kathi on Shearwater (1933) for the photo!]

So that was all well and good for many years.  But during the years after 1950, the volume of vehicle traffic between Tacoma and the Kitsap Peninsula increased to the point that another bridge was needed.  So another bridge that parallels the 1950 bridge was built.  The new bridge was opened in 2007.  Westbound traffic travels on the 1950 bridge; eastbound traffic travels on the 2007 bridge.

2006 photo … construction of the new bridge that would open in 2007.

But hey, Ann, wait a minute … what happened to all of those huge pieces of the original 1940 bridge that fell into the water? Did they remove them from the bottom of the waterway?

Online information will tell you that the collapsed bridge pieces were never raised from the bottom of Puget Sound.  And that’s true.  Every time I cruised under the bridge in my boat, my depthsounder showed piles of strangely angled slabs sitting on the bottom … obviously parts of the bridge.  It’s so deep there (as much as 200 feet deep in the middle) that there’s no danger of a boat or ship hitting any of those pieces.  A few pieces of the bridge were salvaged from the bridge itself and those pieces are displayed in a number of museums in the area.

2011 view of the 2007 bridge (on the left) and the 1950 bridge (on the right).

In fact, speaking of the depth of the water, that 200-foot depth was one of the issues they had to deal with when building the 1940 bridge, and then again with the 1950 bridge, then again with the 2007 bridge … the depth of the water and the speed of the water.  Underwater construction was allowed only 2 hours at a time, and then only twice a day, during daylight hours, because that’s the only time the speed of the water would be slow enough (when the tide was not running) to make it safe for divers to work with the huge pieces of the base of the bridge and the construction equipment that had to be lowered into the water.  Generally, the current stands still (no movement) four times during any 24-hour period … two of those times are at night and two are during daylight hours.  So construction was slow by necessity.

During a 2014 boat cruise to South Sound, I spotted this full-sized US Coast Guard helicopter flying UNDER the bridge.  Gives you an idea how large the bridge is.

Is there a moral to this story?  Well, I guess I’d say that corporate owners and professional engineers/designers should listen to the men and women who do the actual physical work of construction and mechanics.  I’m sure Tubby the dog would agree!  In this case, the men and women who were doing the actual physical construction of the bridge knew there was a problem with the bridge as soon as construction of the center span began, and they had tried to warn their supervisors and the architects.

And yet this story also points out people’s willingness to admit error, learn new things, and figure out a better way.

There are now two bridges side by side, and yet we still say “the Narrows Bridge” even when we mean both of them.  It’s an old habit, calling these combined bridges “the Bridge”.  Change is good sometimes, when you’re fixing a bridge and making it safe … and yet sometimes old habits are good enough. 🙂

The beach on the western Kitsap Peninsula side of the Narrows Bridge.