Reverse curve

Railroad reverse ("S") curve

In civil engineering, a reverse curve (or "S" curve) is a section of the horizontal alignment of a highway or rail route in which a curve to the left or right is followed immediately by a curve in the opposite direction.^[1][2]

On highways in the United States 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.^[3]

On rail routes, reverse curves can cause buffer-locking. On the Northeast Corridor in the United States, these also hinder the development of high-speed rail.^[4]

See also

• S bridge
• Road curve
• Track geometry

References

1. Mundrey (2000). Railway Track Engineering. McGraw-Hill Education. pp. 164–179. ISBN 9780074637241.
2. Harry Rubey (1956). Route Surveys and Construction. Macmillan Publishers. pp. 86–88.
3. Federal Highway Administration (1971). Manual on uniform traffic control devices for streets and highways. U.S. Government Printing Office. p. 67.
4. "Analysis: Long road ahead for improving Northeast Corridor speeds".