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 advantage is only significant when the tracks are fairly level. As soon as the

gradients In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the grad ...

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 Haulage is the business of transporting goods by road or rail between suppliers and large consumer outlets, factories, warehouses, or depots. This includes everything humans might wish to move in bulk - from vegetables and other foodstuffs, to cloth ...

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 A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. The topography, topographic terms acme, apex, peak (mountain peak), and zenith are synonymous. The term (mountain top) is generally used ...

as much as possible, as this reduces the steepness of the gradients on either side. This can be done with a summit

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

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 The term ruling grade is usually used as a synonym for "steepest climb" between two points on a railroad. More simply, the steepest grade to be climbed dictates how powerful the motive power (or how light the train) must be in order for the run to ...

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 include: * dividing the load or splitting the

train In rail transport, a train (from Old French , from Latin , "to pull, to draw") is a series of connected vehicles that run along a railway track and Passenger train, transport people or Rail freight transport, freight. Trains are typically pul ...

, which requires a siding at the summit. * attaching additional banking engine(s). * Using multiple units to divide the load on tractive wheels. * replacing the

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

with a more powerful heavier engine for the duration of the steep grade. * strengthening the track on or approaching the steep grade, allowing higher speeds, and allowing the train a run at the gradient. This can be used in short underwater tunnels, where there is a steep descent just before the climb. * using two-in-one

articulated locomotive An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to neg ...

s such as the Fairlie,

Garratt A Garratt (often referred to as a Beyer Garratt) is a type of steam locomotive invented by British engineer Herbert William Garratt that is articulated into three parts. Its boiler, firebox, and cab are mounted on a centre frame or "bridge ...

Mallet locomotive The Mallet locomotive is a type of articulated steam railway locomotive, invented by the Swiss engineer Anatole Mallet (1837–1919). The front of the locomotive articulated on a bogie. The compound steam system fed steam at boiler pressure ...

. * using a

booster engine A booster engine for steam locomotives is a small two-cylinder steam engine back-gear-connected to the trailing truck axle on the locomotive or the lead truck on the tender. A rocking idler gear permits it to be put into operation by the drive ...

, though this is usually limited to starting the heavy train. * Zig zags *

Spirals In mathematics, a spiral is a curve which emanates from a point, moving farther away as it revolves around the point. Helices Two major definitions of "spiral" in the American Heritage Dictionary are:Horseshoe curves *

Rack railway A rack railway (also rack-and-pinion railway, cog railway, or cogwheel railway) is a steep grade railway with a toothed rack rail, usually between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with ...

Fell mountain railway system The Fell system was the first third-rail system for steep grade railway, railways that were too steep to be Rail adhesion, worked by adhesion on the two running rails alone. It uses a raised centre rail between the two running rails to provide ex ...

Elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...

railways, or

funicular A funicular (, , ) is a type of cable railway system that connects points along a railway track laid on a steep slope. The system is characterized by two counterbalanced carriages (also called cars or trains) permanently attached to opposite en ...

railways driven by

stationary engine A stationary engine is an engine whose framework does not move. They are used to drive immobile equipment, such as pumps, generators, mills or factory machinery, or cable cars. The term usually refers to large immobile reciprocating engines, pr ...

s (cable haulage up and down inclines). * Geared steam locomotives such as a

Shay locomotive The Shay locomotive is a geared steam locomotive that originated and was primarily used in North America. The locomotives were built to the patents of Ephraim Shay, who has been credited with the popularization of the concept of a ''geared st ...

Atmospheric railway An atmospheric railway uses differential air pressure to provide power for propulsion of a railway vehicle. A static power source can transmit motive power to the vehicle in this way, avoiding the necessity of carrying mobile power generating eq ...

Cable car (railway) A cable car (usually known as a cable tram outside North America) is a type of cable railway used for Public transport, mass transit in which rail cars are hauled by a continuously moving Wire rope, cable running at a constant speed. Individual ...

* Rail surface treatment * Compensation for curvature - the gradient is slightly eased on sharpest curves so that the tractive effort to pull the train is uniform.

History

Ruling gradient

Techniques to overcome steep hills

See also