A washaway is a particular kind of landslide that can affect man-made structures such as

cutting Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for wikt:cut, cutting are the knife and saw, or in medicine and science the scal ...

s, embankments and

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

s. They are thus a hazard to railways and road traffic.

Overview

The biggest danger with washaways is that they may be difficult to spot in time to stop short of the point where one falls over the edge and/or into the water where one may drown.

Repairs

An embankment that is washed away can be repaired or restored by replacing the washed away earth, which is necessarily large because embankments have a gentle slope. A quicker method is to replace the washed out earth with a criss-cross structure of timber steepers called a

pigsty A sty or pigsty is a small-scale outdoor enclosure for raising domestic pigs as livestock. It is sometimes referred to as a hog pen, hog parlor, pigpen, pig parlor, or pig-cote, although pig pen may refer to pens confining pigs that are kep ...

which is only slightly wider than the track itself. The pigsty has alternating layers of transverse and longitudinal layers of these sleepers, which contains a lot of air which saves weight. Steel and concrete sleepers are not necessarily suitable for this purpose as they are either not square or fragile. The sleepers in the pigsty can be reused when the washaway is fully repaired. Rails can substitute for the sleepers. The hollow space inside the pigsty should be able to act as a culvert.

Warning devices

A mechanical railway signal that is normally "green" can be put to "red" if a link in the pulling wire is disengaged by a slump of the earth beneath. An electrical railway signal that is normally green can be put to red if a contact is opened circuited by a slump of the earth beneath. One side of contact might be attached to the sleepers, while the other side is buried in the ballast beneath. To protect against a false feed keeping the warning signal green, the circuit should be double cut so that false feeds will connect positive to negative and blow a fuse, forcing the warning signal to red. A similar setup might be used to protect bridges likely to be hit by ship collisions, as with the 1993 Big Bayou Canot train wreck.

Accidents

Railway accidents involving bridge washaways include: * 27 September 1923 – near

Glenrock, Wyoming Glenrock is a town in Converse County, Wyoming, United States. The population was 2,576 at the 2010 census. History Glenrock, known as Deer Creek Station, had its beginning as a mail and stage station along the Oregon Trail. The station served ...

- a bridge over Coal Creek was washed away and a passenger train derailed, killing 30 of the train's 66 passengers. * 24 December 1953 -

Tangiwai disaster The Tangiwai disaster occurred at 10:21 p.m. on 24 December 1953 when a railway bridge over the Whangaehu River collapsed beneath an express passenger train at Tangiwai, North Island, New Zealand. The locomotive and the first six carriage ...

- lahar caused bridge washaway; train thrown into river; 151 killed. * 1974 - Crystal Brook,

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

- train thrown into river after washaway collapses bridge. * 1993 - 114 perished in a passenger train that plunged into a river after floods washaway a bridge at Ngai Ndethya. * 29 October 2005 - Veligonda train disaster - 114 killed * November 2011 - Feroleto-

Marcellinara Marcellinara ( Calabrian: ) is a ''comune'' and town in the province of Catanzaro in the Calabria region of southern Italy. It is a small village located in the middle of the narrowest strip (isthmus) of Italy and one of the narrowest of Europe as ...

, Italy Today's Railway Europe 213, pg 55

Cause unclear

* Peruman railway accident 1988 - 105 killed

References