Rail Transport

Rail transport is the conveyance of passengers and goods by means of wheeled vehicles running along railways (railroads). Rail transport is part of the logistics chain, which facilitates international trade and economic growth.

Typical railway tracks consist of two parallel rails, normally made of steel, secured to crossbeams, termed sleepers (U.K. and Australia) or crossties or ties (U.S. and Canada). These tracks maintain a constant distance between the two rails, a measurement known as the "gauge" of the track. To maintain the alignment of the track it is either laid on a bed of ballast or secured to a solid concrete foundation. The whole is referred to as permanent way (U.K. and Australia) or right-of-way (North America).

Railway rolling stock, which is fitted with metal wheels, moves with low frictional resistance when compared with road vehicles. Locomotives and powered cars normally rely on the point of contact of the wheel with the rail for traction and adhesion (the part of the transmitted axle load that makes the wheel "adhere" to the smooth rail). This is usually sufficient under normal conditions, but adhesion can be reduced or lost through the presence of unwanted material on the rail surface, such as moisture, grease, ice or dead leaves.[1] To counteract such reduction of adhesion, many locomotives have devices which blow fine sand on the rail ahead of the wheels.