Hillclimbing (railway)

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While railways have a great ability to haul very heavy loads, this advantage only really applies when the tracks are fairly level. As soon as the gradients stiffen, the tonnage that can be hauled is greatly diminished.

Some of the techniques that can be used to overcome steep hills include:

dividing the load or splitting the train.
attaching additional banking engine(s).
replacing the engine with a more powerful heavier engine for the duration of the steep grade.
using two-in-one articulated locomotives such as the Fairlie, Garratt or Mallet locomotive.
Zig Zags
Spirals
Horseshoe curves
Rack railway
Fell mountain railway system
Elevators, cable railways, or funicular railways driven by stationary engines (cable haulage up and down inclines).
Geared steam locomotives such as a Shay locomotive
Atmospheric railway
Cable car (railway)

1 History
2 Ruling gradient
3 See also

[edit] 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.

[edit] Liverpool and Manchester Railway

This pioneering railway was built at a time when choice between locomotive and cable haulable was not clear cut. Therefore all hill climbing (1 in 100) sections was concentrated in one place where cable haulage by stationary engines could be used if necessary, while the rest of the line was engineered to be so gently graded (say 1 in 2000) that even primitive locomotives would have a chance of succeeding. As it turned out at the Rainhill Trials of 1829, locomotives proved capable of handling the short 1.6-km length of 1 in 100 gradients on either side of the Rainhill level.

Since the early trains had primitive brakes, it was also necessary to have very gentle gradients to reduce the need for strong brakes. Sudden changes in gradients would have also overstressed the primitive couplings between the carriages.

The gentle 1 in 2000 gradients were made possible by very substantial earthworks and bridges.

[edit] Cromford and High Peak Peak Railway

The CHPR also opened in 1830 but had gradients so steep - 1 in 8 - that cable haulage was essential. It hauled mainly coal. [1]

[edit] The Redruth and Chasewater Railway

This line, a narrow gauge route across the Cornish peninsular (planned in 1818, opened in 1825) used a significant incline to access the harbour at Portreath, which like many in Cornwall sits in a steep valley.

[edit] Lowering the summit

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.

On the Lancaster and Carlisle Railway (L&CR) of 1847 a deep cutting was cut at the Shap Summit. This cutting was cut through rock, about 0.5 mile (800 m) in length, and is between 50-60 feet (15-20 m) deep.

A summit tunnel can lower the summit even more, and paradoxically, the steeper the hill, the shorter the tunnel tends to be; 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. Notorious tunnels came to be known as rathole tunnels.

[edit] Ruling gradient

The ruling gradient of a section of railway line between two major stations is the gradient of the steepest stretch. The ruling gradient governs the tonnage of the load that the locomotive can haul reliably.