08-16-2017, 08:57 PM
This is a very attractive design to include in your railroad. It follows a construction style similar to our Pony Truss bridge. However, it has a clear difference that gives it a character of its own and will add more interest and variety to its line.
Examples of this and its counterpart, the inverted rope bridge, can still be seen along the Penrith line, Keswick and the Cockermouth Railway. Despite being a standard branch, the track crossed the Greta River eight times using both vertical and inverted examples of rope bridges.
The lateral structures consist of an arched beam, maximum height 100mm in the center sloping down section by section at each end. The vertical and diagonal members support the beam. All the sections are of square section of aluminum of 12mm x 12mm connected by plates of 1.5mm riveted with blind rivets of 2,4 mm. The main cover and the lateral structures are supported in robust "T" section beams of 25 mm x 25 mm.
Bridges have always been considered as "works of art" in the domain of Structural Engineering. Among them, the bridges with "upper arch" stand out for their aesthetics of first class. Numerous tied bow bridges have been designed and built over the last 50 years, many of which are Bowstring type. The term "bowstring" is the result of actual behavior for this type of balanced structure. The upper arc "arch", always strongly compressed, is internally balanced by the tensioned cover, which functions as a "rope". From the conjugation of the two elements, the results of the bow rope tied bridge