Glossary of rail transport terms

Rail terminology is a form of technical terminology. The difference between the American term railroad and the international term railway (used by the International Union of Railways and English-speaking countries outside the United States) is the most significant difference in rail terminology. These and other terms have often originated from the parallel development of rail transport systems in different parts of the world. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist. Various terms, both global and specific to individual countries, are listed here. Where a term has multiple names, this is indicated. The abbreviation "UIC" refers to standard terms adopted by the International Union of Railways in its official publications and thesaurus. Harmonic rock or harmonic rock and roll The condition of locomotives and cars swaying in opposite directions when traversing depressions on the roadbed. A potentially dangerous condition that can cause coupler damage, lading damage, or derailments at slower speeds. Head-End Power A scheme whereby the locomotive engine or a separate generator provides hotel power to carriages Headboard A sign attached to a locomotive to identify a named train or charter, or for other special occasions Headstock A transverse structural member located at the extreme end of a rail vehicle's underframe. The headstock supports the coupling at that end of the vehicle, and may also support buffers, in which case it may also be known as a "buffer beam". Heavy haul Heavy freight operations High rail The upper rail in a curve or superelevation, which typically experiences higher lateral loads and greater wear Hole A passing siding. Inferior trains "lay over in the hole" to let superior ones pass. Home signal See absolute signal.