Hillclimbing (railway): Difference between revisions

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Hillclimbing is a problem faced by railway systems when a load must be carried up an incline. While railways have a great ability to haul very heavy loads, this is only possible when the tracks are fairly level. As soon as the gradients increase, the tonnage that can be hauled is greatly diminished.

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.

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.

Techniques to overcome steep hills

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

Railway layout to reduce gradient

Compensation for curvature: the gradient is slightly eased on sharpest curves so that the tractive effort to pull the train is uniform.
Horseshoe curves
Spirals
Zig zags
A descending momentum gradient on the approach to a hill allows a train to increase speed before a climb.^[1]

Track type

Rail surface treatment
Fell mountain railway system
Hanscotte centre-rail system
Rack railway
Elevators, cable railways, or funicular railways driven by stationary engines (cable haulage up and down inclines)

Motive power

Using a booster engine, though this is usually limited to starting the heavy train
Using two-in-one articulated locomotives such as the Fairlie, Garratt or Mallet locomotive
Replacing the engine with a more powerful heavier engine for the duration of the steep grade
Attaching additional banking engine(s)^[2]
Using multiple units to divide the load on tractive wheels
Geared steam locomotives such as a Shay locomotive
Atmospheric railway^[3]

Modifying the load

Dividing the load or splitting the train, which requires a siding at the summit

References

^ Kadiyali, L. R. (2016). Transportation Engineeering. New Delhi: Khanna. pp. 69, 290. ISBN 9789382609858.
^ Kadiyali (2016) p. 291
^ Buchanan, R. A. (1992). "The Atmospheric Railway of I.K. Brunel". Social Studies of Science. 22 (2): 231–243. ISSN 0306-3127.

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+{{Short description|Railway in which a load is carried up an incline}}
-{{Africa-geo-stub}}
+{{More citations needed|date=November 2024}}
+'''Hillclimbing''' is a problem faced by railway systems when a load must be carried up an incline. While railways have a great ability to haul very heavy loads, this is only possible when the tracks are fairly level. As soon as the [[Grade (slope)|gradients]] increase, the tonnage that can be hauled is greatly diminished.
+== History ==
-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.
+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 [[cut (earthmoving)|summit cutting]].
-Some of the techniques that can be used to overcome steep hills include:
+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.
-* divide the load
-* attached additional (bank) engines
-* replace engine with heavier engine for duration of steep grade.
-* use two-in-one [[articulated locomotive]]s such as the [[fairlie]], [[garratt]] or [[mallet]].
-* [[Zig Zag (railway)|Zig Zags]]
-* [[Spiral (railway)|Spirals]]
-* [[Horseshoe Curve (railway)|Horseshoe Curve]].
-* [[rack railway]].
-* [[Fell mountain railway system]].
-* [[Stationary engines]] (cable haulage up and down inclines).
-* [[Geared steam locomotive]] - [[Shay]]
-* [[Atmospheric railway]]
+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.
-==History==
-The early tramways and railways were laid out with very gentle grades because locomotive and horse haulage where so low in tractive effort. The only exception would be with a line that was downhill all the way for loaded traffic. Remeber also that brakes were very primitive at this early stage.
+== Ruling gradient ==
-===Liverpool and Manchester Railway===
+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.
-This pioneering railway was built at a time when choice between locomotive and cable haulable wasn't 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 there 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 1.6km length of 1 in 100 gradients on either side of the Rainhill level.
+== Techniques to overcome steep hills ==
-== See Also ==
+Some of the techniques that can be used to overcome steep hills are:
+===Railway layout to reduce gradient===
+* Compensation for curvature: the gradient is slightly eased on sharpest curves so that the tractive effort to pull the train is uniform.
+* [[Horseshoe curve (railway)|Horseshoe curves]]
+* [[Spiral (railway)|Spirals]]
+* [[Zig zag (railway)|Zig zags]]
+*A descending ''momentum gradient'' on the approach to a hill allows a train to increase speed before a climb.<ref>{{cite book |last1=Kadiyali |first1=L. R. |title=Transportation Engineeering |date=2016 |publisher=Khanna |location=New Delhi |isbn=9789382609858 |pages=69, 290}}</ref>
+===Track type===
+* [[Rail surface treatment]]
+* [[Fell mountain railway system]]
+* [[Hanscotte centre-rail system]]
+* [[Rack railway]]
+* [[Elevator]]s, [[Cable railway|cable]] railways, or [[funicular]] railways driven by [[stationary engine]]s (cable haulage up and down inclines)
+===Motive power===
+* Using a [[booster engine]], though this is usually limited to starting the heavy train
+* Using two-in-one [[articulated locomotive]]s such as the [[Fairlie locomotive|Fairlie]], [[Garratt locomotive|Garratt]] or [[Mallet locomotive]]
+* Replacing the [[Locomotive|engine]] with a more powerful heavier engine for the duration of the steep grade
+* Attaching additional [[bank engine|banking engine(s)]]<ref>Kadiyali (2016) p. 291</ref>
+* Using multiple units to divide the load on tractive wheels
+* [[Geared steam locomotive]]s such as a [[Shay locomotive]]
+* [[Atmospheric railway]]<ref>{{cite journal |last1=Buchanan |first1=R. A. |title=The Atmospheric Railway of I.K. Brunel |journal=Social Studies of Science |date=1992 |volume=22 |issue=2 |pages=231–243 |url=https://www.jstor.org/stable/285614 |issn=0306-3127}}</ref>
+===Modifying the load===
+* Dividing the [[Cargo|load]] or splitting the train, which requires a siding at the summit
+==References==
+{{reflist}}
+== See also ==
+{{div col|colwidth=22em}}
+* [[Cable car (railway)|Cable car]]
+* [[Funicular railway]]
+* [[Grade (slope)]]
+* [[Lickey Incline]]
 * [[Mountain railway]]
+* [[Rack railway]]
+* [[Ruling gradient]]
+* [[Slope]]
+* [[Steepest gradients on adhesion railways]]
+{{div col end}}
+{{Railway track layouts}}
 [[Category:Rail technologies]]

v t e Railway track layouts
Railway track	Single track Passing loop Double track Quadruple track Crossover
Rail sidings	Balloon loop Headshunt Pocket track Refuge siding Rail yard Classification yard
Junctions	Flying junction Level junction Double junction Facing and trailing Grand union Grand circle / roundabout Wye Switch / turnout / points Swingnose crossing Level crossing
Stations	Railway platform Bay Island Side Split Terminal station Balloon loop Spanish solution Cross-platform interchange Interchange station Infill station
Hillclimbing	Horseshoe curve Zig Zag / Switchback Spiral
Track geometry	Track gauge Ruling gradient Minimum curve radius Cant Cant deficiency