![Railroad_](https://upload.wikimedia.org/wikipedia/commons/b/b7/Railroad_%22S%22_Curve.jpg)
In
civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewage ...
, a reverse curve (or "S" curve) is a section of the horizontal alignment of a highway or railroad route in which a curve to the left or right is followed immediately by a curve in the opposite direction.
On highways in the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
reverse curves are often announced by the posting of a W1-4L sign (left-right reverse curve) or a W1-4R sign (right-left reverse curve), as called for in the
Manual on Uniform Traffic Control Devices
The ''Manual on Uniform Traffic Control Devices for Streets and Highways'' (usually referred to as the ''Manual on Uniform Traffic Control Devices'', abbreviated MUTCD) is a document issued by the Federal Highway Administration (FHWA) of the Unit ...
.
Reverse curves on the
Northeast Corridor
The Northeast Corridor (NEC) is an electrified railroad line in the Northeast megalopolis of the United States. Owned primarily by Amtrak, it runs from Boston through Providence, New Haven, Stamford, New York City, Philadelphia, Wilmington, a ...
in the
USA
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
hinder the development of
high-speed rail.
Reverse curves cause
buffer-locking.
See also
*
S bridge
An S bridge is a bridge whose alignment follows a reverse curve, shaped roughly like a shallow letter S in plan, used in early 19th-century road construction in the United States. They were generally used for crossing small, curving streams wi ...
*
Road curve
*
Track geometry
Track geometry is concerned with the properties and relations of points, lines, curves, and surfaces in the three-dimensional positioning of railroad track. The term is also applied to measurements used in design, construction and maintenance of t ...
References
Railway track layouts
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