Mystery Bridge Nr. 83: The Twin Bridges of Salisbury, CT

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Postcard courtesy of Dana and Ray Klein

After some time looking at the mystery bridges in the German state of Saxony, our next Mystery Bridge takes us back to the United States and the community of Salisbury in northwestern Connecticut. With a population of 3655 inhabitants, the town, incorporated in 1741, is part of the New York Metropolitan Region, which encompasses the entire state. Salisbury is laden with many historic buildings dating back to the time of its incorporation, some are listed on the National Register of Historic Places. Because of its proximity to Mount Frissell in Massachusetts, the community is situated on the highest point in the state, with an elevation of 2380 feet above sea level. And lastly, the community has six lakes and several ponds. And with that come many bridges, although in high numbers.

And with the high number of bridges in the community, come the difficulties of finding rare structures and mystery bridges with missing information, like these two bridges in the postcard above.

Posted recently on bridgehunter.com by Dana and Ray Klein, one can see clearly that the bridge on the left was for pedestrians- on the right for horse and buggy and later, the Model T cars. The setting is around the turn of the century because of their design and appearance. Given the high number of trees and the given facts above, the twin bridges spanned a waterway connecting a pair of lakes and/or ponds. The question here is where exactly the bridge is located.

A closer look at the two bridges show that the material used for construction was clearly iron (most likely, cast iron), for two reasons:

  1. The pedestrian bridge features a curved design, namely curved endposts, and appears to have some artistic designs on the trusses, similar to the ones found at Central Park in New York City. These bridges were built in various areas between 1865 and 1880. It’s unknown what exactly the truss type was given the transversal view in the postcard.
  2. The vehicular bridge featured a Parker pony truss span, using the earliest design by C.H. Parker when it was patented in 1884. The connections were pin-connected, but unlike other regular Parker designs built after 1890, the upper chord consists of eyebar beams built in short lengths per panel with four or five put together. The vertical and diagonal beams are integrated into this mechanism and pins are used to connect all of them. In the picture, you can see how far apart they are, in comparison with conventional pin-connections, whose vertical beams are inserted into the upper chord, and pins are used solely for the diagonal beams. When Parker introduced his design, wrought iron was already being used, even though it was being phased out in favor of steel because of its flexibility and tolerance to heat. From 1890 onwards, all truss bridges were being built using this material. Therefore, because iron was used for circular designs and ornaments, in comparison to steel used for other geometrical shapes, such as rectangular ones, the bridge was built between 1885 and 1890.

Both bridges are long gone, but it would be curious to know the following questions:

  1. Where were the bridges located?
  2. When were the bridges built? The Parker was most likely between 1885 and 1890, while the pedestrian span was built before 1885.
  3. Who built the bridge?
  4. What were the dimensions of the two bridges?  For both, it appears to have the length of between 40 and 70 feet. The pedestrian span had a width of between 10 and 20 feet; the vehicular one, between 15 and 25 feet.
  5. When were they removed? Most likely because of the progressive development of the infrastructure combined with population growth, they were gone before 1960 latest, unless they were relocated. If relocated, where could one see the bridge today?

Do you know about the bridges, then send the author a line or post the information on the Chronicles’ facebook page. You can also comment on bridgehunter.com, where the postcard came from. In either case, we would like to know more about the structures.

So happy bridgehunting! 🙂

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Mystery Bridge Nr. 79: How to Reconvert a Truss Bridge- Going from Deck to Through Truss in Oklahoma

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Photos courtesy of Mark W. Brown

Our 79th Mystery Bridge takes us to Oklahoma; specifically to Whitesboro in LeFlore County and this bridge. Spanning the Kiamichi River at Township Rd. 4044C south of Whitesboro, this bridge is one of the most unusual through truss bridges a person will ever see in the United States. According to the data from Bridgehunter.com, the total length of the bridge was 270 feet with the largest span being 127 feet, the width of the bridge is around 13-14 feet and the vertical clearance is 13.3 feet. Yet despite the date of construction being ca. 1940, this bridge is unusual as it is a pinned connected through truss, thus bucking the standards of truss bridge construction. As many resources have indicated, most truss bridges built at this time had riveted or welded connections, making the structure sturdier and able to carry heavier loads. Pinned connections had a tendency of dislocating or even having the bolts connecting the beams to break off, causing bridge failure. This resulted in many of the structures being taken off the state highway system and relocated onto less-used township roads beginning in the 1920s and extending well into the 1950s, especially as the US was lacking materials and engineers as a result of World War II. Judging by the appearance of the bridge, it appears to have been built between 1910 and 1915 as this was the cut-off period for constructing truss bridges with pinned connections. It was congruent to the time standardized bridges were approved by the state governments, which included not just focusing on truss bridges with riveted connections and either Howe lattice or lettered portal bracings (namely, A, X, M and West Virginia framed), but also the key truss designs, which were the Pratt, Parker, K-truss, Warren, Polygonal Warren and in some cases, Pennsylvania petit.

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The Whitesboro Bridge features a Warren through truss, but looking at the structure further, it appeared that in its former life, it was a deck truss bridge that had many spans, totaling at least 500-600 feet. One can see how the overhead bracings were added, which consisted of thin cylindrical steel beams. Furthermore, there is no portal bracing, like other truss bridges, and lastly, when looking at the joint where the upper beam and the diagonal end posts meet, the upper beam appears to have been sawed off.  According to observation by fellow pontist, Mark W. Brown, the piers are 2-3 feet wider on each side and 1-2 feet higher, thus creating a slight slope when entering and crossing the structure. Two theories go along with the piers: either they were installed when the bridge was built or they were reinforced after the bridge sustained structural damage because of flooding.

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It is possible that this crossing was the first to have been built as the town expanded because of the baby boomer population. But the expansion did not last as many people moved to bigger cities for job opportunities. As of the 2008 Census, the population of the town incorporated in 1908 and named after one of the founders is only 1298. The hunch is that the highest population of Whitesboro was about 3,400 by 1960.

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The Whitesboro Bridge has a design that is not like any unusual designs developed by the engineers at all. It is neither a Pegram nor a Kellogg, now is it a Schaper truss, which you can see in many truss bridges built in Germany and other parts of Europe. This bridge is definitely a repurposed truss bridge, having gone from its previous life as a deck truss spanning one of the state’s greatest rivers, like the Red and the Canadian, to one spanning a smaller river but on whose width justified a through truss span.

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This leads us to the following questions:

  1. When exactly was this bridge built and was there a previous structure?
  2. Who was the mastermind behind this repurposing project and why did the engineer choose this?
  3. Where did the bridge originate from?
  4. When was this built and who was the bridge builder?
  5. Are there other remnants of that bridge left besides the one at Whitesboro?
  6. What do we know about Whitesboro aside the facts and figures presented in wikipedia?

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Got any leads, please share in the comment sections here as well as in the Chronicles’ facebook pages. You can also contact Jason Smith at the Chronicles, using the link here. As this bridge is eligible for the National Register of Historic Places, any information you have or can find will help build a solid case for its nomination, let alone preserving it for future generations. As Oklahoma is losing historic bridges in large quantities in the past 8 years, the time is ripe to preserve what’s left of its culture, especially when it comes to unusual designs like this bridge in Whitesboro.

 

Special thanks to Mark W. Brown for bringing this to the author’s attention and for providing some interesting pics of this bridge.

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