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Cut (earthmoving)

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Road cutting

In civil engineering, a cut or cutting is where soil or rock material from a relative rise (elevated landscape) to an earlier section of the route is cut out to make way for a further section of the route, whether canal, road or railway line. It can also be used in river management to speed the flow of the river, short-cutting a meander.

Talerddig cutting through the granite Cambrian Mountains, Wales in 2001. Created as part of the Newtown and Machynlleth Railway, with a depth of 120 feet (37 m), it was the deepest cutting in the world at the time of its opening in the early 1860s. The original near-vertical sides have since been trimmed back

In cut and fill construction and across uneven terrain it keeps the route straight and/or flat, where the comparative cost, desirability or practicality of alternate solutions (such as an indirect route or the alternatives of embankment or similarly raised viaduct) for the desired incline are prohibitive. In road and rail, cuttings provide low noise pollution relative to the use of at-grade solutions, viaducts or embankments. Contrary to the general meaning of a cutting in construction the term specifically refers to land mechanically excavated, hand-dug or, mainly in mountainous examples, blasted out with explosives.

Some cuts may be made on the approach to a slope or a cliff, which may be tunneled. Others may be made directly through the middle or top of a hill or similar relative rise. A cut is by definition open at the top. Where covered it is a cut-and-cover tunnel as opposed to a bored tunnel.

Open-cut station of the New York City Subway

Cuts are typically used to reduce the length and (often more importantly) the grade of a route.

Cuts can be created by multiple passes of a shovel, grader, scraper or excavator, or by blasting.[1] One unusual means of creating a cut is to remove the roof of a tunnel through daylighting. Material removed from cuts is ideally balanced by material needed for fills along the same route, but this is not always the case when cut material is unsuitable for use as fill.

The word is also used in the same sense in mining, as in an open-cut mine. The use of cuttings often provides byproducts as a form of mineral extraction, commonly sand, clay or gravel; the cost of building drains, reinforcing banks against landslide and a high water table are factors which commonly limit its use in certain areas.

Contents

HistoryEdit

The term cutting appears in the 19th century literature to designate rock cuts developed to moderate grades of railway lines.[2] Railway Age's Comprehensive Railroad Dictionary defines a cut as "a passage cut for the roadway through an obstacle of rock or dirt".[3]

Types of cutEdit

There are at least two types of cut, sidehill cut and through cut. The former permits passage of a transportation route alongside of, or around a hill, where the slope is transverse to the roadway or the railway. A sidehill cut can be formed by means of sidecasting, i.e., cutting on the high side balanced by moving the material to build up the low side to achieve a flat surface for the route. In contrast, through cuts, where the adjacent grade is higher on both sides of the route, require removal of material from the area since it cannot be dumped alongside the route.[4]

Lock cutEdit

 
A lock cut on the River Thames at Bray Lock, Berkshire. The tall wooden poles are designed for boats to tie on to while awaiting entry into the lock.

A lock cut is a section of a river or other inland waterway immediately upstream and downstream of a lock which has been modified to provide locations for boats to moor while waiting for the lock gates to open or to allow people to board or alight vessels.

A ledgeEdit

A ledge is a cut in the side of a cliff well above the bottom of a gorge

Notable cutsEdit

Notable canal cutsEdit

Notable railway cutsEdit

 
Excavation of Olive Mount cutting, Liverpool. Watercolour by T.T.Bury (1833) The cutting was 20 ft (6.1 m) wide and 70 ft (21.3 m) deep. Construction required the removal of 480,000 cubic yards (370,000 m3) of sandstone.

Notable roadway cutsEdit

See alsoEdit

ReferencesEdit

  1. ^ Herbert L. Nichols, Jr., and David A. Day, P.E., Moving the Earth: The Workbook of Excavation, 5th ed. (New York: McGraw-Hill, 2005), pp. 8.16 et seq.
  2. ^ Alexander Smith (1875) A new history of Aberdeenshire
  3. ^ Robert G. Lewis et al., eds., Railway Age's Comprehensive Railroad Dictionary (Omaha, Neb.: Simmons-Boardman Books, 1984), p. 48. This reference does not include a definition for the corresponding term fill.
  4. ^ Nichols and Day, Moving the Earth, p. 8.16.