Flooding

How flooding causes delays - and what the industry is doing to reduce them

Many sections of the railway were built in cuttings and tunnels which are lower than the surrounding area, or on flat, low-lying land with limited drainage, making them prone to flooding.

The development of land near the railway can increase the risk of flooding - if the drainage system is inadequate, rain which previously soaked into the ground may run off tarmac and concrete and straight onto the tracks.

When the water level rises above the rails, trains have to reduce their speed to prevent damage to the train. If the track has a live conductor rail, flooding can cause a short circuit.

Trackside points and signalling equipment can fail when water enters their housings and may need replacing before services can resume.

Flood water can wash away the ‘ballast’ – the bed of stones that supports the sleepers – and this destabilises the track. To make the line safe again, this ballast must be re-laid.

How the industry is reducing delays caused by flooding

• When flood warnings are received from the Environment Agency and Flood Forecasting Centre, staff and equipment are deployed to at-risk areas so that action can be taken quickly
• Flood defence systems are deployed, including barriers with a membrane that seals to prevent water getting through, and inflatable barriers which are filled with flood water
• Branches, leaves and debris are cleared from ditches and drainage systems on and near the railway
• Building pumping stations in locations which are prone to flooding so that flood water can be quickly pumped away
• When flood-prone lines are renewed, the tracks and signalling equipment are installed at a higher level
  
• Planning applications for developments near the railway are reviewed to make sure they include adequate drainage systems