Howe Truss

The W&A was known for having many railroad bridges along its 138 mile line. Over Chickamauga Creek alone there were about 12 crossings such as this Howe Truss. The model bridge pictured below depicts a Howe Truss that crossed the Tenneesee River. It could also be one of the Chickamauga Creek branches. Both bodies of water were traversed by Howe Trusses as well as other types, in many cases they would have been covered bridges. The TN River was also crossed by other RailRoads local to Chattanooga. Prototypically, however, the TN was not crossed by the W&A. And Chickamauga Creek North empties into the TN farther north of Chattanooga, too far prototypically speaking for my needs. With respect to this layout, the TN River would most likely be at this position but would be much wider than the area depicted on my line. Hense, I invoked the law of selective compression.

Period photos, especially along the Tennessee River and Chickamauga Creek, show bridge remains and some that were rebuilt. Although slight alterations may have existed in the rebuilds, I am more interested in the remains as they are more likely to be most prototypically accurate.

Given some information I uncovered, bridge elements were made with 30' timber lengths. I estimated that these bridge sections, in general, were approximately 90'. This offered the opportunity for a bridge model long enough for that dramatic and more authentic appearance and was built to accomodate three sections spanning 270 scale feet.

At this stage the bridge is completed, abutments have been placed and we are now contouring the river's landscape. Brian has been working on the backdrop and has included Lookout Mountain, a most prominent land feature distinguishing the Chattanooga area. I will be sure to include this in a future posting.

The following photos are described below the picture.


This section on the W&A is just on the outskirt of Chattanooga. The bridge is constructed with mostly bass and spruce with some balsa. Piers will be a styrofoam core wrapped with a new Chooch product, Flex Wall. I was considering carving the foam but  this product is dead on for the actual stone.   

  

Here you can see an error in my modeling the bridge cross ties. Looking at the period photo the appeard to be planks. Thanks to Bernie, and a realization how shadows can be deceiving, I have replaced the planks with standard beams, I believe 8"x8". The pier is this photo is from ARC or AIM (?). Bernie, I believe, mentions this in one of his notes as to who manufactures piers.  



One of the many questions regarding bridge construction was how did engineers join bridge sections. One of my  'senior advisors' and construction engineers, Christopher, while helping me view photos, saw what appears to be a long brace connecting these 90' sections. The piers of course would be placed just below these braces and the section joints.

Stay tuned for more posts as we reach completion.