Railway tree census singles-out “problem trees” helping to reduce costs and improve safety

Instances of train delays caused by trees falling onto the tracks could dramatically reduce as Network Rail, the company responsible for running and maintaining the railway, rolls-out a national “tree census” database with the ability to identify and target specific trees that could eventually cause problems for train passengers.

More than 10 million trees growing next to the railway have been catalogued as part of a sophisticated aerial survey covering 20,000 miles of Britain’s track. The database provides engineers with a heat map indicating higher priority “problem trees” or overhanging tree canopies which need attention before they fall onto the railway and cause delays to train journeys. Part of the Offering Rail Better Information Service programme (ORBIS), the database, now completed and deployed across the company, will revolutionise the way lineside engineers target their work, as well as save the company time and money.

By providing its engineers with an early warning system to identify potential problem trees and canopies encroaching on the railway before they fall, the ORBIS programme is saving tax-payer funded Network Rail thousands of pounds in repair and clean-up costs. Tackling potential problem trees early will also help improve the safety of our railways by reducing the likelihood of a train colliding with a fallen tree or branch.

A fallen tree damages a train near Cupar, Scotland during a storm in January 2015
A fallen tree damages a train near Cupar, Scotland during a storm in January 2015

The tree census is the latest offering from ORBIS, a transformation programme aimed at supporting the railway industry by collating, analysing and exploiting data from a variety of disparate sources  – from Brunel-era working drawings on parchment, ordinance survey maps, water and gas board plans, to high-resolution aerial and oblique imagery and Light Detection And Ranging (LiDAR) 3D imagery. So far, the ORBIS initiative has saved Network Rail £207 million by helping engineers make smarter decisions, and “predicting and preventing” incidents. New additions to the programme, like the tree database, mean ORBIS is forecast to save £281m by 2019.

The new programme allows engineers to target individual trees that could cause problems
The new programme allows engineers to target individual trees that could cause problems

Paul Meads, head of lineside safety at Network Rail said: “Our analysis revealed the majority of trees that fall on the railway during storm conditions are healthy – yet previous inspections may have assessed these as lower risk. We’ve surveyed up to 60 metres either side of the railway covering 20,000 miles, and catalogued over 100 different attributes per tree including height, thickness, health, slope angle, proximity to bridges and power lines etc., which are measured to predict the risk an individual tree represents to the railway.”

10 million trees were surveyed, 60m either side of the railway
10 million trees were surveyed, 60m either side of the railway

Alex Hinshelwood, Network Rail’s senior asset engineer in Wales, uses the database in his day-to-day work and has already seen the cost, safety and environmental benefits. He said: “From the first use of the data I was able to identify areas to be managed and remove the need for a tree survey in those locations. This allowed for immediate cost saving for the route.

Overgrown trees pose a risk to the railway, damaging equipment, trains and causing delays
Overgrown trees pose a risk to the railway, damaging equipment, trains and causing delays

“From my desk, I can analyse the trees that pose a risk to the railway, and using this data, I am able to develop a work bank for our vegetation management teams. Now, with targeted, evidence-based information, I can save money and reduce the need to carry out lineside surveys.

Engineers can use the
Engineers can use the “tree census” database to better plan work

Data

“The new heat map is an extraordinary development; I can click on the Cardiff area and in an instant highlight where potential problem areas exist. The clustering data shows how many trees exist and you can drive right down to individual trees to uncover a range of different details, from height and location, to tree width.

A heatmap shows engineers potential problem areas
A heatmap shows engineers potential problem areas

Environment

“We can’t simply cut down every tree on the lineside; we have to consider the natural environment and the impact of our work on our lineside neighbours. The vegetation management data has the potential to completely change the way we carry out vegetation and tree management across the routes and will be an invaluable tool that can be used with our existing inspection records and asset data to help us make real asset management decisions.”

ORBIS helps reduce cost and improve safety in vegetation management
ORBIS helps reduce cost and improve safety in vegetation management

Railway tree facts:

  • Britain’s 52,000 hectares of railway land are home to millions of trees, bushes and other plants
  • There are 10 million trees growing 60 metres either side of the railway, covering 20,000 miles – some of these trees lie beyond our borders but may still affect the railway. Essentially, this is an area large enough to cover every tree that could possibly impact the railway
  • So far this year, we have targeted and managed ‘hotspot’ areas for vegetation management covering 900 hectares – which accounts for roughly two per cent of the network
  • A mature tree can have between 10,000 and 50,000 leaves and each autumn thousands of tonnes of leaves fall onto railway lines across the country. Compressed by passing trains, these leaves create a thin, black ‘Teflon’-like layer on the rail which – much like black ice on the roads – can affect train braking and acceleration as a result of reduced friction between train wheels and rail
  • Last year there were over 470 incidents involving vegetation on the railway (April 2016 – March 2017). This includes fallen trees, branches, overhead line dewirements, leaf mulch etc.
Tree on the line in West Highlands after Storm Gertrude in January 2016
Tree on the line in West Highlands after Storm Gertrude in January 2016