A light railway is a railway built at lower costs and to lower standards than typical "heavy rail": it uses lighter-weight track, and may have more steep gradients and tight curves to reduce civil engineering costs. These lighter standards allow lower costs of operation, at the price of lower vehicle capacity.
Narrow gauge
thumb|Restored [[Molli railway at Kühlungsborn, Mecklenburg, Germany ()]]
The precise meaning of the term "light railway" varies by geography and context.
In countries where a single standard gauge is dominant, the term light railway does not imply a narrow gauge railway. Most narrow gauge railways operate as light railways, but not all light railways need be narrow gauge. After Spooner's development of steam haulage for narrow gauge railways, the prevailing view was that the gauge should be tailored according to the traffic: "The nearer the machine is apportioned to the work it has to do the cheaper will that work be done."
From the 1890s, it was recognised that cost savings could also be made in the construction and operation of a standard gauge railway: "light axle-loads and low speeds, not gauge, are the first condition of cheap construction and economical working. Gauge is quite a secondary factor."