Rail Joints
Although a rail joint has always been an integral part of the railway track, it is looked upon as a necessary evil because of the various problems that it presents.
Earlier, rails were rolled in short lengths due to difficulties in rolling and the problem of transportation. With increase in temperature, rails expand and this expansion needs to be considered at joints. It was, therefore, felt that the longer the rail, the larger the required expansion gap, and this too limited the length of the rail. A rail joint is thus an inevitable feature of railway tracks, though it presents a lot of problems in the maintenance of the permanent way. This chapter discusses the various types of rail joints and their suitability on a railway track.
Effects of a Rail Joint
A rail joint is the weakest link in the track. At a joint, there is a break in the continuity of the rail in both the horizontal and the vertical planes because of the presence of the expansion gap and imperfection in the levels of rail heads. A severe jolt is also experienced at the rail joint when the wheels of vehicles negotiate the expansion gap. This jolt loosens the ballast under the sleeper bed, making the maintenance of the joint difficult. The fittings at the joint also become loose, causing heavy wear and tear of the track material. Some of the problems associated with the rail joint are as follows.
Maintenance effort
Due to the impact of moving loads on the joint, the packing under the sleeper loosens and the geometry of the track gets distorted very quickly because of which the joint requires frequent attention. It is generally seen that about 30% extra labour is required for the maintenance of a joint.
Lifespan
The life of rails, sleepers, and fastenings gets adversely affected due to the extra stresses created by the impact of moving loads on the rail joint. The rail ends particularly get battered and the hogged and chances of rail fracture at joints are considerably high due to fatigue stresses in the rail ends.
Noise effect
A lot of noise pollution is created due to rail joints, making rail travel uncomfortable.
Sabotage chances
Wherever there is a rail joint, there is a potential danger of the removal of fish plates and rails by miscreants and greater susceptibility to sabotage.
Impact on quality
The quality of the track suffers because of the excessive wear and tear of track components and rolling stock caused by rail joints.
Fuel consumption
The presence of rail joints results in increased fuel consumption because of the extra effort required by the locomotive to haul the train over these joints.
