A mountain railway is a railway that ascends and descends a mountain slope that has a steep grade. Such railways can use a number of different technologies to overcome the steepness of the grade. Mountain railways commonly have a narrow gauge to allow for tight curves in the track and reduce tunnel size and structure gauge, and hence construction cost and effort.
On steep grades the friction between the wheels and the rails cannot apply sufficient adhesion to the train's wheels so as to overcome gravity, and the train is in danger of sliding down the track. In practice this affects downhill braking capability before it affects uphill climbing ability, and some mountain railways at the lower end of the steepness spectrum rely on standard adhesion for propulsion, but use special track brakes acting directly on the rails.
Where the line is too steep to rely on adhesion for climbing, a rack railway may be used, in which a toothed cog wheel engages with a toothed rack rail laid between the tracks. A now little used alternative to the rack and pinion railway is the Fell system, in which traction and/or braking wheel are applied to a central rail under pressure. Another alternative is a cable car in which the car's weight is on rails but grasps a moving cable underneath the rails for propulsion. This is used in San Francisco's famous cable cars
Finally at the steepest end of the spectrum, a funicular railway may be used. Here a cable is used to haul counterbalanced trains up and down the track. The car itself is often custom built for the slope, with specially raked seating and steps rather than a sloped floor. Taken to its logical conclusion as the slope becomes vertical, a funicular becomes an elevator.
Read more about Mountain Railway: List of Mountain Railways, Mountain Railways in Fiction
Famous quotes containing the words mountain and/or railway:
“The mountain stood there to be pointed at.
Pasture ran up the side a little way,
And then there was a wall of trees with trunks;
After that only tops of trees, and cliffs
Imperfectly concealed among the leaves.”
—Robert Frost (1874–1963)
“Her personality had an architectonic quality; I think of her when I see some of the great London railway termini, especially St. Pancras, with its soot and turrets, and she overshadowed her own daughters, whom she did not understand—my mother, who liked things to be nice; my dotty aunt. But my mother had not the strength to put even some physical distance between them, let alone keep the old monster at emotional arm’s length.”
—Angela Carter (1940–1992)