A washaway is a particular kind of

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environmen ...

that can affect man-made structures such as cuttings, 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 someth ...

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 On September 22, 1993, an Amtrak train derailed on the CSX Transportation Big Bayou Canot Bridge near Mobile, Alabama, United States. It was caused by displacement of a span and deformation of the rails when a tow of heavy barges collided with th ...

Accidents

Railway accidents involving bridge washaways include: * 27 September 1923 – near Glenrock, Wyoming - 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 -

lahar A lahar (, from jv, ꦮ꧀ꦭꦲꦂ) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley. Lahars are extr ...

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

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, 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 o ...

- 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, Italy Today's Railway Europe 213, pg 55

Cause unclear

* Peruman railway accident 1988 - 105 killed

References