Rock netting and stabilisation

What we’re doing to help prevent landslips and the delays they cause

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

Landslides 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.

What we do when there’s a landslip

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, we will often need to re-route services.

Before trains can run on the line again after a landslip, we’ll remove any debris and check 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 our 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.

How we’re reducing delays caused by landslips

• It’s important that we identify the sites prone to landslips to ensure that we keep passengers and our engineers safe. The main method for doing this is by regular examination by our engineers.
• Where we know that sites are at risk of landslip, we can employ a number of different techniques for monitoring, including motion sensors and CCTV to detect soil and rock movement.
• We can also carry out works to improve the stability of the slope ranging from maintenance to large scale interventions.
• When we get flood warnings from the Environment Agency and Flood Forecasting Centre, we send people and equipment to the at-risk areas so we’re in a position to act quickly.
• You can read more about our work to reduce landslips in our Earthworks Technical Strategy document.

Earthworks and managing vegetation

In order to keep our earthworks safe, it is often necessary to manage vegetation.

While in some cases, the presence of vegetation may be beneficial to the stability of an earthwork slope, in many cases the presence of vegetation has a detrimental effect.

This can include:

• roots dislodging blocks from the slope;
• trees causing shrinkage of clay slopes leading to settlement of the track;
• vegetation preventing access to the slope to inspect or carry out maintenance activities.

The decision to remove vegetation from an earthwork slope will generally seek to balance the vegetation effect on the earthwork with the impact on other parts of the railway and the environment.