Mystery Bridge 22: A truss bridge made of wood

All photos courtesy of Craig Philpott, used with permission. This is the side view of the truss

Here’s a quiz for you: How many of you had either a set of Lincoln Logs, Tinker Toys, or something similar to that, when you were a child growing up? And if so, what kinds of things did you build with your set?  I remember when I was growing up, I used to build human beings with my set of Tinker Toys and covered bridges and telephone poles with Lincoln Logs. But like many engineers and bridge enthusiasts, I was different from those who were supposed to build log cabins and other skeletal structures, as was directed on the package.  Yet if we go back 100 years, many engineers and bridge designers referred to the Erector Set to get their imagination going. It was a set of steel beams with nuts and bolts, which allowed them to spend hours perfecting their ideal building- or bridge.

Perhaps the person who built this bridge in California used the combination of the three to design and patent this truss bridge. The Dinkey Creek Bridge is a jewel that was found by one fellow pontist two years ago while hiking through the Sierra Nevada National Forest. Built in 1938 by the Civilian Conservation Corps, this bridge spans the creek which snakes its way through the forest from neighboring Fresno, in Fresno County. It is one of the most unique examples of bridges that were built during the era, where President Franklin Roosevelt encouraged bridge designers and builders- most of them out of work because of the Great Depression- to build something that will attract tourists and last forever. And for this bridge, it is something that is worth seeing. It was the first bridge to be built using Redwood trees and the first to use steel, split-ring timber-connecting devices, which enabled the bridge to handle heavy traffic, which was rare in this area when it served traffic. Yet the truss design can be confusing, for when looking at the pictures provided by Craig Philpott, it appears to be a Parker Truss because of its polygonal shape, even though the State of California considers it a bowstring arch bridge. While there are some examples of bowstring arches that have a polygonal-like shape, 90% of all bowstring arch bridges were built with the top chord creating an arch, like a bow and arrow, as seen with the Turkey River Bridge in Winneshiek County, Iowa (now extant).  In addition, it is unknown who designed this unique bridge, let alone oversaw the construction of the bridge, even though a couple workers have been honored recently for their work.

This leads us to two questions about the Dinkey Bridge, our Mystery Bridge:

1. Is this bridge a bowstring arch bridge or a Parker truss bridge? Please ignore the fact that the bridge is a through truss.

2. While the CCC was responsible for the construction of the bridge, who designed the bridge and utilized the steel connectors? And who oversaw the whole process.

Have a look at the pictures and let the author know, using all the channels available. The bridge is listed on the National Register of Historic Places and is now a pedestrian bridge serving a local inn. It’s one of the bridges in the Sierra Nevada Mountains that is a must-see when passing through.

Special thanks to Craig Philpott for allowing the author to use the photos.

Photos:

Portal view

Oblique view with green background

This entry was posted in Bridge Profile USA, Forum, Mystery Bridge and tagged , , , , , , , , , , , , , , , . Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>