An adhesion railway relies on adhesion traction to move the train. Adhesion traction is the friction between the drive wheels and the steel rail. The term "adhesion railway" is used only when it is necessary to distinguish adhesion railways from railways moved by other means, such as by a stationary engine pulling on a cable attached to the cars or by railways that are moved by a pinion meshing with a rack.

The friction between the wheels and rails occurs in the wheel-rail interface or contact patch. The traction force, the braking forces and the centering forces, all contribute to stable running. However, running friction increases costs by requiring higher fuel consumption and by increasing the maintenance needed to address fatigue (material) damage, wear on rail heads and on the wheel rims and rail movement from traction and braking forces.