Question

​A railway engineer who looks after the maintenance of rails is quite fed up of the extensive maintenance that is required at the hundreds of joints in the rails. The gaps between short sections of rails have to be constantly checked. Also they cause the rail ride to be rough. He wants to design a railroad without these joints. However, he knows that expansion on heating is a fact of life and cannot be done away with.
He thinks of using much longer rails to reduce the number of gaps, and hence the maintenance. However, it is pointed out by a colleague that this would not work because longer rails also meant that the gaps had to be longer. This would make the ride rougher and could also prove to be dangerous–the train could derail at these joints.

Answer these questions.
1. Why would the gaps be longer if longer sections of rails are used?
2. Can you offer a solution that would do away with the gaps?

Answer 1

(1) A gap between the sections of rails is necessary because due to heating rail tracks undergo linear expansion and their length is increased. Longer sections of rails mean longer expansion in them, hence longer gaps would be required.

(2) We can use long welded rails(LWR) and continuously welded rails(CWR). The expansion/contraction of LWR and CWR is taken care of by a device called Switch Expansion Joint (SEJ) at the ends. The welding of rails reduces maintenance efforts of the track.