Question

why sleepers are provided under railway tracks

Answer 1

Wooden or concrete sleepers are kept beneath the railway line so that there is less weight of the train on the ground and rail route line may not sink into the ground.

The wooden sleeper is made from a variety of softwood and hardwoods timbers, oak, jarrah and karri being popular hardwoods, hardwood railway sleepers are generally much more durable and naturally longer lasting.