The Purdy Bridge

The Purdy Bridge

“The future is the past”,

(Joseph Roth, “Report from a Parisian Paradise, Chap. 18, Nîmes and Arles”) 

Current Purdy Bridge (Harbor History Museum Smugmug, BD&R-072-Pdy.jpeg

When I read that sentence, I immediately thought how true, and yet how few people realize the truth of it.  And what does that have to do with a blog about the Purdy Bridge in the greater Gig Harbor community?

In 1936 when Homer More Hadley (1885-1967) came up with the idea behind the design of this, the fourth bridge to be constructed across the Purdy Spit in Henderson Bay, it was and still today considered to be the most innovative, especially when you consider its central span is 190 feet in length.  In 1936 this was the longest single span among concrete girder forms.  There are two additional 140 foot girder spans and two 40 foot cantilever ends extending beyond the concrete box piers.  The roadway provided by the bridge is 2 lanes measuring 20 feet wide from curb to curb.  (The bridge was rehabilitated in 1966)

The Purdy Bridge is on the National Register of Historic Place, NRHP #82004274, Smithsonian Number 45P100658, and was listed July 16, 1982.  Washington HAER No. WA-101.

As mentioned previously this is the fourth bridge —- the first was just a wooden structure supported by timber piers built in 1892.  It was replaced in 1905 but the swift tidal currents which can reach 10 miles per hour washed away some of the pilings and the bridge collapsed.  The waterway was under the jurisdiction of the US Department of War, and after receiving complaints from the ship owners, Pierce County was ordered to tear down the temporary bridge that was built following the collapse.

Pilings from the first bridge , Harbor History Museum Smugmug, Pdy-05.jpeg

Erik Sandin near second bridge, Harbor History Museum Smugmug, BD&R-110-Pdy.jpeg

So in 1919-1920 the County widen the roadway and rebuilt the bridge with a steel swing span.  But again problems arose but this time it was not the tidal currents but instead a lawsuit filed by the nearby property owners and residents.

2nd Steel swing span bridge, Harbor History Museum Smugmug, BD&R-036-Pdy.jpeg

This is when the hero appeared —- not a bridge engineer or architect but instead a regional structural engineer for the Portland Cement Association —-  Homer More Hadley!

Hadley suggested a design popular in Europe but rarely used in the US.  He suggested a concrete box girder and suggested W. H. Witt Company in Seattle prepare the engineered drawings and specifications, and to include W. H. Craft, a resident engineer, as a member of the team.  Pierce County Engineer and supervisor, Forest R. Easterday completed the team members.

There were several other designs submitted for the replacement bridge, but the major advantage of Hadley’s hollow box girder design was the low cost.  Using Hadley’s idea, the design cost came in at $62,000.

Current Purdy Bridge, Harbor History MuseumSmugmug, BD&R-075-Pdy.jpeg

During WWI - 1918 - Hadley worked as a concrete engineer for the United States Shipping Board Merchant Fleet Corporation.  In this capacity he had the opportunity to study and learn about concrete construction as used in Europe.  Because his bridge has been considered a rival to Eugène Freyssinet (1879-1962) we should have a quick glimpse into Freyssinet’s background.  

Freyssinet was a French structural and civil engineer and the major pioneer of prestressed concrete.  His most significant early bridge was the three span Pont le Veurdre near Vichy built in 1911 and 238 feet spans.  This bridge enabled Freyssinet to discover “the phenomenon of creep in concrete, whereby the concrete deforms with time when placed under stress.”  In 1919 he designed a 435 foot arch span at St. Pierre du Vauvray, and the largest single span in the world in his Pont de la Liberation in Villeneuve-sur-Lot measuring 315.78 feet.  Then in 1930 he designed his largest structure Plougastel Bridge with three identical spans of 592 feet, completed in 1930.  

When you get an idea of Freyssinet’s background it is easy to understand that Hadley, an American concrete engineer at the same time in history would be fascinated by the possibilities of concrete in his professional.

And all of this brings us back to 2018 and the conversations between the State of Washington Transportation Department and Pierce County Roads Department as they work through the problems currently presented by the Purdy Bridge.  

Daily traffic across the bridge is in the 20,000s (I don’t know the exact number although it has been report it was 21,268 in 2012), and the bridge condition is marked as poor by BridgeReports.com.  With an election just weeks away, all the local politicians are including the Purdy Bridge in their talking points.

Will the powers that be be able to save the historic bridge similar to how they saved the Narrows Bridge by building a second span and reconditioning the current span?  Will they demolish the existing bridge and start from scratch?  Do you think it is important to save the current bridge?  

Notes:

• Joseph Roth “Report from a Parisian Paradise”
• Washington HAER Inventory no. WA-101
• HistoryLink.org
• http:/bridgehunter.com/wa/pierce/purdy/
• Homer More Hadley (Civil Engineer) [pcad.lib.washington.edu]
• Eugène Freyssinet [wikipedia.org]

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