Why wooden blocks are kept under railway lines?

Question

india railways

Answer 1

They are sleepers (or ties in US and Canada) which keep the rails to the correct gauge and have fixings which stop the rail 'creeping' in the direction of the train.

Concrete and sometimes metal sleepers may also be used.

Answer 2

They support the rails, and expand and contract at a very low, and predetermined rate. Treated lumber doesnt react to extremes in temperature as concrete or some other material might, and since they lay in a bed of gravel, the vibration caused by the train rolling over them allows them to vibrate with it and not offer the resistance what would cause cracking and breaking of a more solid media.

Answer 3

There are wooden supports under all rail lines as far as I know.   I would think they use wood because it expands & contracts with the weather & doesn't break down as easily as concrete with the weight of the trains.

Answer 4

they give leveling support for the tracks and will not bust apart like cement

Answer 5

All correct.  But there are some distinct advatages to using wooden cross ties over concrete or relatively newly introduced steel cross ties.

For one thing, they actually hold up better in the event of a derailment than concrete ties.  If, by way of example, a freight car should drop one wheel, or a whole truck, off the rail, it can and does often travel for miles with these one or two wheels on top of the tie.  The ties get cut up pretty good, but it often allows more time for the crew or a trackside detector to become aware of the problem before you wind up with tonnage scattered all over h**l and back.

With a concrete cross tie, when a wheel hits them, being so rigid and therefore brittle, they pretty much explode, right now.  No second chance to prevent a calamity.  Though concrete ties are in wide spread use, they came about as a technological improvement for high speed trains.  In this instance, there is a rubber "snubber" under the tie plate between the tie, tie plate and the rail to dissipate energy while still being held firmly in place.  In these instances, the rail is secured by using bolts, where the wooden cross ties have the tie plates and secured by the age old rail spike.

With conventional operations, the wooden cross ties have a bit of "give" to them on a verticle plane.  This way, with heavy freight cars and locomotives, as opposed to light weight high speed equipment, some of the energy that is imparted through track/train dynamics is dissipated by the flexibility, reducing the mechanical energy and associated forces developed where wheel meets rail.

As mentioned above, there are devices that keep the rail from moving in a longitudinal plane, which are called "creepers."  The tie plates and spikes keep the rail secured in the horizontal (side to side) plane.

Surprisingly, as far as longevity is concerned, wooden cross ties preserved with creosote have nearly the same useful life span as does a concrete tie.

Answer 6

for two things, to provide support and to reduce or eliminate static electricity.

Answer 7

Mainly as a support for the lines,preventing both sideways or up and down movements.The wooden blocks, called sleepers, are embedded in the ground or ballast.The support is through metal plates, bolts and clips.This fastening also keeps the distance between the parallel lines constant,which is very important to avoid derailments.