Changes to train times

 

Landslip

How landslips can cause delays - and what the industry is doing to reduce them

A landslip on the railway is generally defined as when soil, rocks and earth fall onto and either wholly or partially obscure the track.

Also known as landslides, they can occur anywhere, moving either slowly or quickly. When they impact on railways, roads and other infrastructure, they can cause a lot of disruption.

They commonly occur when the ground becomes saturated with water after long periods of heavy rain. As the earth becomes heavier, the water forces apart grains of soil so that they no longer lock together – resulting in a landslip as the structure becomes loose and unstable.

When landslips happen, unfortunately so do delays. A train can’t swerve to avoid debris on the line in the same way a car can avoid a small obstruction on the road, so when there‘s debris on the tracks after a landslip, services will often need to be re-routed.

Before trains can run on the line again after a landslip, any debris will be removed and checks will be carried out to ensure that the infrastructure is safe and working.

There are ongoing concerns, even after an initial landslip. Once a landslip has started to move, the slope is permanently weakened. It means it’s much more likely that there will be further landslips. Some of the slopes – or cuttings, as they’re also known – on either side of the tracks need to be strengthened by improving drainage or adding stronger materials to the slope itself, such as steel rods or soil nails. This work to stabilise the earth can take time.

What the industry is doing to reduce delays caused by landslips

  • To identify sites prone to landslips, helicopters are used equipped with laser imaging, detection and ranging
  • At high risk sites, motion sensors and CCTV are used to detect soil and rock movement. These send an alarm to the signaller who will stop the trains until the area has been inspected by engineers
  • Slopes are stabilised by putting in drainage or using steel rods or soil nails
  • If these options are not sufficient, the slope will be re-profiled to reduce its angle, making it less prone to a landslip
  • Warnings are received from the Environment Agency and Flood Forecasting Centre when flooding is likely. Staff and equipment are then deployed to at-risk areas to be in a position to act quickly

Last updated:   11 January 2017