Nev
Underneath the Arches - Skewed-Arch Railway Bridge
Before steel became widely available arched bridges were constructed from stone, this design is very strong as the weight of the bridge and any load crossing is transmitted through the arch and into the ground. There are many stone arch bridges still in use today which is a testament to their strength and of the designers of yesteryear.
Usually an arched bridge is constructed so that each end of the bridge sits at right angles to the gap it crosses, but when the gap is not going to be at right-angles, for example crossing a river, either the span needs to extend for longer, which makes the bridge more costly or the arch can be constructed skewed, which allows the bridge to span the obstacle in the shortest available distance.
Unlike an arch bridge where the stones are cut at right-angles, the skewed-arch bridge required each piece of stone to be cut at a unique shape to create the skew, hence this skewed-arch bridge for road traffic was typically avoided as it is a complicated method of construction so roads were curved to suit the bridge.
Due to the expansion of the railway industry the skewed-bridge design was used more frequentlybecause of the numerous obstacles that had to be crossed where a conventional arch bridge was not practical, for example over a river. The railway needs to travel in as straight a line as possible and themost cost-effective way of achieving this was the construction of the skew-arch bridge. I have attached for your viewing pleasure a conventional stone arch bridge used for road traffic and a skewed arch bridge
