London Underground has an enlightened policy of balancing safety issues with environmental protection. As you will read here in this piece from the Tube’s website, Network Rail’s arrogant clear cutting policy is not the only way -indeed, it may cause more problems than it solves.

TAKE A BOUGH

Preparing for leaf fall
They provide a sound buffer between trains and neighbouring properties, they encourage wildlife, and their roots keep embankments in place by helping to stop water erosion.
But – as many people know – trees also have leaves. And leaves can cause lots of problems for trains.
The time of ‘leaf fall’ comes every autumn. It may not sound dangerous, but as any commuter knows, leaves can – and do – stop trains in their tracks. When leaves fall onto the track, they get crushed by passing trains.
The squashed leaves then form a slippery and treacherous film that means the train wheels can’t grip the tracks properly.
The obvious solution would be to cut down all the trees and bushes that might cause trouble. But as IBCV Section Track Manager for Environment Michael Palmer points out, good management of the vegetation alongside the tracks on the Central Line means that trains and trees can co-exist.
“We spray weedkiller in a 2 metre band either side of the tracks,” he says. “We also inspect and remove diseased trees and dead branches, and regularly prune the trees to thin the canopy.
“If we take any trees away, we take care to replant trees that don’t shed as many leaves, or ones that shed the kind of leaves that don’t give us a problem.”
‘Good’ trees include the evergreen oak (because it doesn’t shed its leaves at all) and the hornbeam (the canopy grows close to the trunk and limits the area into which leaves fall).
Shrubs such as broom, laveteria, berberis, laurels and holly can also be ideal, as they only grow to around six feet and don’t shed their leaves.
As well as planting and pruning, Michael’s team also treats the tracks with a substance known as Sandite, which aids the grip of wheels.
Sandite is a thick gel containing grains of sand, which covers the rails and provides friction for the wheels.
But there’s more to tree management than dealing with leaves. Michael’s team of thirteen prunes and maintains trees and bushes all year round along the Central Line.
As it’s London’s longest Tube line, that’s 74km, or 46 miles to deal with.
The team also repairs fences, kills weeds, clears platform areas of vegetation (and snow in winter), and also clears signals, drains, ditches and airshafts.
Michael needs to keep one eye on the smooth running of the trains, whilst keeping the other firmly on his responsibility for wildlife. “We will always wait for the young of birds or squirrels to leave nests before we remove branches or cut down whole trees,” he says. “People love them or hate them, trees are a fact of Tube life.
“Some people love trees, some hate them; some of the Line’s neighbours want us to do away with the trees, others are very passionately defensive of them.
We have inherited some beautiful trees – oak and ash and beech. We check them all out regularly, and make sure they are kept healthy, and thinned out so they don’t drop too many leaves – either on the track, or in neighbouring gardens.”
And looking after the trackside vegetation properly has brought other dividends. “We have a good relationship with our neighbours now,” says Michael.
“It’s because we make an effort to keep the trees in a manageable -and managed -state.”
Leaves on the line
Many people believe the Tube is the only railway which suffers delays every autumn caused by falling leaves on the line. This is not so. We reproduce here a reader’s letter to The Times newspaper of 6 November 2002 on page 32. The column is called Questions Answered.
Do other countries’ railway systems grind to a halt at the onset of autumn owing to a surprise fall of leaves on the line?
The simple answer is “yes”, but the public, press and media do not make a fuss about it.
Just as wet leaves on a pavement can cause loss of footing, they can cause steel wheels to lose firm contact with steel rails.
In Paris, commuters on some lines only too aware of autumn leaves on the line.
The Dutch know the problem as well and have been experimenting with the Sandite used in this country. In Germany, the Munich Stadtbahn usually gets stitched up at this time of the year – yes, leaves again.
And only the other week on the Oberammergau branch, the brand new trains had to be taken off as they cannot cope with…leaves on the line.
Thiry years ago in Sweden, it was not unknown for a special banking locomotive to be positioned at Norrkoping station to help southbound trains to start away in autumn because of the number of trees near the station.
The problem has worsened everywhere as we have become “greener”. There were not as many trees and bushes along railway lines years ago – steam locomotives regularly set fire to embankments and this helped to keep things under control.
However, even in those far-off days, it was not unknown for freight trains to take less tonnage in autumn when adhesion conditions were bad.
What’s my tree?
Oak: Quercus robur
Here comes the science bit:
A large tree (35 metres) with a wide crown, and broad bole bearing low branches at right articles. It is often planted in woods, parks and gardens.
What use is it?
Buildings, ships, barrels, furniture, wheel spokes, charcoal.
In autumn, acorns make useful missiles for throwing at people who annoy you. Also squirrels can use them as props for family pictures.
Hornbeam: Carpinus betulu
The science bit:
The hornbeam grows to 25 metres and has a fluted, buttressed bole, and grey bark with metallic-blue and pale brown veins. The leaves are dark green and glossy above and paler below, with a short red-brown petiole.
What use is it?
Butchers’ chopping blocks, shoe lasts, skittles, wooden screws, industrial cogs and pulleys. Pyromaniacs and bakers may like to note that the timber makes good fuel for bread ovens.
Ash:Fraxinus excelsior
Here comes the science bit:
With smooth grey bark and glabrous leaves that are green even in autumn, the ash grows up to 40 metres high and prefers damp, calcareous soil.
What use is it?
Wheel rims, ladder rungs, tool handles, oars, hockey sticks, tennis rackets and billiard cues. The timber is shock absorbent, and presumably ideal for making go karts, pogo sticks, heavyweight clubs and other so-called ‘blunt instruments’.
Sycamore: Acer pseudoplatanus
Here comes the science bit:
An abundant tree that tolerates salt spray and city pollution. It reaches around 35 metres in height and has smooth grey bark, which is whorled and cracked higher up.
What use is it?
Kitchen utensils, draining boards, rollers and furniture. The seeds are sometimes affectionately called ‘helicopters’, and because of the cool way they fall to the ground, can be a good way of getting children interested in nature. For about five minutes.
http://tube.tfl.gov.uk/content/faq/faqs/trees.asp