A climate-resilient railway

We’re reducing flood risk by using drainage systems that do not increase flooding elsewhere. This includes our green tunnels, which use a cut-and-cover technique. We dig a trench, build the tunnel structure, then cover it with soil and plants. These plants act as a natural drainage system.

We’re also building ditches, culverts and other drainage structures, including slabs. Slabs drain water quickly, prevent erosion and keep the ground stable. This means the HS2 line is designed to withstand a one in 1,000-year rain event.

Hot weather can make overhead power lines expand and sag. It can also buckle rails and make the ground beneath the railway unstable. This can close lines or force trains to travel at slower speeds, causing disruption for passengers.

Our tracks have rail expansion devices to manage how rails expand and contract as they heat up and cool down. These devices, along with our drainage systems, will keep trains moving even when cold temperatures and snow hit the UK.

Points are the moveable sections of the line that allow trains to switch between tracks. They can freeze in cold weather, bringing the railway to a halt. All HS2 points will have a heating system that turns on automatically when temperatures drop below a certain level. This keeps them working in icy weather, helping trains run on time.

Old Oak Common station has exposed surfaces that will absorb heat from the sun as it enters through the roof-lights and other unshaded areas. This will reduce the risk of the indoor air temperature rising.

We have developed a climate change adaptation and resilience strategy for our stations as part of our work on BREEAM, a measure of sustainability for new and refurbished buildings.

Overhead power lines can be brought down in strong wind, causing major disruption to rail services. To reduce this risk, we’re using an updated version of the overhead power lines developed for the Lyon to Marseille high-speed line.

To improve resilience against strong winds, masts carrying overhead electric wires are placed closer together on sections exposed to stronger winds, like those on viaducts. Sharing the load between more masts reduces the weight each one carries. Distances between masts on HS2 will be between 45 metres and 72 metres.

Landslips can cause major disruption. Earth can spill onto the tracks from above or crumble away beneath a line, causing the railway to close. This often happens on the existing railway after long periods of heavy rain, when the ground becomes saturated.

We’re building HS2 with significantly shallower cuttings and embankment slopes than on the existing Victorian-built railway. This significantly improves stability.

We’re also carefully planting vegetation and using non-shrinkable soils, which avoid absorbing large quantities of water. Extensive built-in drainage will keep the ground stable beneath the railway.

Thousands of tonnes of leaves fall onto railway lines each autumn. When trains crush them, they create a slippery layer on the rail, similar to black ice on roads. This makes it harder for trains to accelerate or brake.

We will not plant the types of trees that cause this problem. We will also plant trees well away from the line to stop them being blown onto tracks during strong winds.