History
Early tramways and railways were laid out with very gentle grades because locomotive and horse haulage were so low in tractive effort. The only exception would be with a line that was downhill all the way for loaded traffic. Brakes were very primitive at this early stage.
Where a railway has to cross a range of mountains, it is important to lower the summit as much as possible, as this reduces the steepness of the gradients on either side. This can be done with a summit tunnel or a deep summit cutting.
A summit tunnel can lower the summit even more, and steeper hills result in shorter tunnels. Also, tunnels cost the same no matter how much overburden there is, while cuttings tend to increase in cost with the square of the overburden.
Care had to be taken with summit tunnels in the early days of steam with designs that suffered from problems with smoke and slippery rail.
Read more about this topic: Hillclimbing (railway)
Famous quotes containing the word history:
“I believe that history has shape, order, and meaning; that exceptional men, as much as economic forces, produce change; and that passé abstractions like beauty, nobility, and greatness have a shifting but continuing validity.”
—Camille Paglia (b. 1947)
“The principal office of history I take to be this: to prevent virtuous actions from being forgotten, and that evil words and deeds should fear an infamous reputation with posterity.”
—Tacitus (c. 55–c. 120)
“A country grows in history not only because of the heroism of its troops on the field of battle, it grows also when it turns to justice and to right for the conservation of its interests.”
—Aristide Briand (1862–1932)