Benefits of TfL's green infrastructure

Most of the green infrastructure we own and manage forms corridors of woodland, street trees, scrub and grassland. These are part of London's cultural heritage and act as a safe haven and dispersal route for plants and wildlife, including bats, badgers and reptiles.

It also helps to:

  • Make London more attractive for walking and cycling
  • Improve the mental health and wellbeing of our staff, neighbours and customers
  • Reduce the risk of flooding on our networks and surrounding areas
  • Improve air and water quality and store carbon
  • Provide shade, shelter and cooler conditions along our roads and railway lines
  • Stabilise trackside embankments

Find out how we're enhancing green infrastructure across our network and London as a whole.

Key facts and figures

  • Around a third of our land is covered by vegetation
  • We have up to 436 hectares of tree canopy cover which is nearly 22% of our land
  • We have 124 Sites of Importance for Nature Conservation (SINCs) covering 484 hectares, or 24% of TfL land

Green infrastructure targets

We are legally obliged to consider biodiversity conservation as part of our policy- and decision-making.

Greeen infrastructure is identified in the Mayor's Transport Strategy as a key element of Healthy Streets. The Healthy Streets Approach lays out how green infrastructure can improve public areas and the environment as part of transport projects.

The Mayor's Transport Strategy, the London Environment Strategy and our Corporate Environment Plan, commit us to:

  • Achieving a net gain in biodiversity across our estate
  • A 10% increase in biodiversity for relevant TfL projects, in line with the Environment Act
  • A 10% increase in tree canopy cover on our estate
  • A 1% annual increase in tree numbers on our road network
  • Incorporating Sustainable Drainage System (SuDS) into our highway schemes
  • No net loss of Sites of Importance for Nature Conservation (SINC)

How we manage our green infrastructure

Our main focus when managing our green infrastructure is on safety - for our customers, neighbours, staff and contractors.

If not managed well, vegetation can reduce sight lines on an approach to a busy road junction or fall on tracks and highways. This means that we often have to cut back or remove vegetation.

Our green infrastructure is managed by tree and landscape experts, including vegetation inspection teams who are qualified to make safety and risk assessments. The green infrastructure on our estate is an asset, and we try to only remove any of it as a last resort.

We:

  • Assess the condition of trees every year - this is done by competent professional arboriculturists
  • Remove trees if they are dead or diseased and before they can fall and disrupt services, damage property, or harm people. Replacement trees will be planted where they are appropriate
  • Remove trees where subsidence has been proven and it is necessary to protect property or embankments from further damage
  • Prune vegetation that prevents vehicles or pedestrians from using the highway or track

We also explore opportunities to introduce green infrastructure as part of our projects.

Roadside vegetation

We manage 580 kilometres of principal roads in London, known as red routes. This includes around 165 hectares of roadside verges, central reservations and green space on roundabouts. We're also responsible for managing more than 24,000 street trees and plant new street trees as part of our annual tree planting programme.

We try to balance the need to keep busy routes on our road network running smoothly with the aim of protecting and enhancing green infrastructure. This mean regular planned maintenance and pruning vegetation to ensure signals and sightlines are clear for drivers.

Keeping diseased trees and vegetation for wildlife habitat is not as easy on our road network as it would be in a natural woodland. Still, we are committed to maintaining a resilient street tree population and enhancing biodiversity on our road network. This includes trying to reduce the number of times grass is cut in some areas to encourage wildflowers and pollinators.

Trackside vegetation

Our standard for managing trackside vegetation requires that all trees, shrubs and flowers planted are compatible with running the railway. Green infrastructure has many benefits, but can also create issues we must manage. Our trackside environment is regularly monitored to ensure rail infrastructure and tracks are safe for operations.

Falling trees and leaves

Extreme weather conditions can affect the safety and performance of our network and services. Falling trees and leaves on and around tracks can cause delays and serious safety risks, as well as damage to our trains. We try to reduce this risk by keeping specific areas near the track clear, such as the area between where the rails sit and the trackside land.

Trackside fires

In dry conditions any build up of debris and foliage can ignite suddenly. These fires can affect the safety of our customers and staff, as well as disrupt services.

We reduce this risk by regularly clearing dry vegetation from rails and trackside areas.

Embankment stability

Green infrastructure can help make embankments and cuttings more stable. However, if diseased or damaged trees are not treated or removed, they can undermine this stability and threaten the safe running of the railway.

We take a selective approach to how we manage vegetation growth on embankments.

Non-native invasive species and weeds

Non-native invasive species and pests can cause a lot of damage to our green infrastructure, transport infrastructure and health. For example, oak processionary moth caterpillars not only cause a risk to human and animal health, but can strip whole oak trees bare of leaves, while Japanese knotweed can damage structures like walls and roads.

We use several different methods (chemical and mechanical) to deal with weeds and non-native invasive species. We make sure that we follow the legislation and Government guidelines that apply to any method we use.

We're looking for ways to reduce our use of herbicides. For example, we're trialling the use of electricity as an alternative way of controlling invasive weed species on sites across our highways and Tube network. The trial's results will help us understand the benefits and if it represents best value for money and the least environmental impact.

Telling our neighbours

We write to our neighbours if we're cutting down trees nearby and the work will take three or more nights. This includes work that may need to take place immediately to address safety issues found during a visit. We're not required to consult or get planning permission before cutting down a potentially dangerous tree within the boundary of London Underground property.