Railway slide fence

The fence is designed to retain a rockslide if possible, but if it is displaced by such it also can cause the signaling system to display a restrictive aspect to approaching trains.

[1] The mechanical slide fence parallel to the rails consists of a series of tensioned wires strung about 10 inches (25 cm) apart on poles.

This allows the relay to open, indicating that a slide has occurred thus causing the approaching signals to display a stop or slow aspect.

A slide fence is typically found in a rock-cut area, where rocks could fall on the track and present a danger to approaching trains.

Used extensively throughout French Alps, where passenger trains routinely travel at speeds in excess of 200kph through areas prone to rock slides.

After stopping, the train may obtain permission from the dispatch center to proceed slowly, watching for a dangerous rock slide.

This causes signals on either side of the slide fence to display a restricting indication, requiring trains to travel at a speed enabling them to stop within one-half the range of vision.