Shape of Railway Track
Why the railway track is in I shape ?
What is the shape of railway track ?
Railway tracks are in parallel even though some crossings are there, the pair track is always parallel and will not meet together. Generally speaking the track consists of two parallel steel rails and sleepers in between. In fact, the tracks are laid upon the sleepers with the help of spikes, bolts, lag screws, clips. Clips are often pandrol clips.
Baseplate which is considered as tie plate is used between sleepers and rail. This is done in order to spread the load of the rail evenly through the large area of the sleeper. Spikes are used through holes in baseplate. The purpose of this is to hold the rail in its position, as baseplates are fitted with sleeper and rails are with baseplates.
Steel rails are used in laying the tracks because steel is good enough to carry heavy load than the other materials. Generally the tracks are laid over a bed of coarse which are the crushed stone often called as ballast. When this is done, it combines the flexibility and resilience. In some well developed nations concrete slabs are used in place if coarse, where the rail tracks are laid upon.
If you look at the tracks, then you can find that the shapes are not normal rather the track is in I shape. This is closely related to the bridges that are being constructed today. Considering a bridge, the bottom base, middle pillar and the top road will produce an I shape together. In the very same way, since for a track earth cannot be dug, so there is a base and middle beam like structure and top flat, so that it is looking like I shape.The reason behind this is the track can evenly spread the load along the axis. Also the flat bottomed rail can rest calmly on the sleeper and the top can carry the gauge. The heavier the track the heavier is the load the train can carry and even faster.Scientifically teh bending stress and breaking stress pattern are success when we go for I shape, means the efficiency is highest.
The grade for a track is related to the weight over the length. As said above the speed and load carrying capacity of the train is directly proportional to the weight of the track. Weight mark is punctured on the web side of the track. Generally the track would weigh 40-60 kg per meter.
A track is usually of 20 m in length and hence we need some mechanism to join the tracks. Fishplates are small plates that measure 60 cm , almost 2 feet in length, that are used to join the tracks. And the bolts used are oppositely oriented.
Continuous Welded Rail CWR
In contradict to the joints in the tracks, nowadays the tracks are laid as continuous welded rails which is known as CWR. This is also referred to as ribbon rails. The type of welding used for CWR is flas butt welding. When there is a flaw in the welded joints, the type of welding used to repair the flaw is thermite welding. Since there are only a few joints as the CWR track can extend upto several kilometers, this type of track is very strong.
In modern days, tracks are laid on concrete instead of conventional sleepers or track ballast. This is mainly applicable in tunnels and also the regions where there is drastic climate change; because during winter the metals contract and in summer the metals expand. To withstand this large variation in weather, pandrol fastclip is used and is a captive to the baseplate which is more sustainable and suitable for insertion and withdrawl.
Shape of Railway Track