Its that time of the year again. Where you arrive at the station only to find that your train delayed, the excuse given for the delay is leaves on the line. Every Autumn its the same old reason and has been going as far back as the early days of rail. But what does the yellow army of Network Rail do to try and compact the problem?
Rail Head Treatment Train (RHTT)
The Railhead Treatment Train or RHTT for short is Network Answer to the yearly problem. This train made up of a locomotive at each end followed by wagons containing sandite which is a sand-like gel that sticks to the rails and prevents leaves from being able to stick to to the railhead. A water spray is used in front of the sandite to remove any leaves already on the rails. Only then is the sandite applied to the rails.
New Kid on the block
Last year network rail spent £540,000 on additional leaf blasting equipment the new trains are no longer made up of a locomotive and wagons but are instead a fixed formation maintenance train. The trains have the benefit of being able to move under their own power, freeing up locomotives for other uses. Such as high priority freight.
The art of cleaning the track with the new trains is the same. The train spray’s water onto the track at such high pressure that any leaves are removed. Then sandite is applied to the rail surface. However, as with any new equipment, there are improvements and the water spry on the new trains is so powerful that it cannot operate when the train is not moving otherwise it will easily cut through the solid steel rails.
Network Rail Southern Region’s Rob Davis said: “It’s so important for our passengers to know we’re doing all we can to keep trains moving reliably for them, particularly during the COVID crisis where people need more space. We’re seeing much more wet and windy weather these days and our fleet of trains is running 24/7 to deal with the leaves that those conditions leave on the line.
“Our train fleet uses water jets to blast the rails clean, at such high pressures that if we stopped the trains from moving they would actually cut clean through the steel. We also lay a paste of gel and steel filings to help trains grip and keep signalling systems working properly.
“This year they will run 300,000 miles over the Southern Region, from Weymouth to Whitstable and all points in between, and will lay almost 50,000 miles of gel on the way. We’re also continuing to manage our trees by the railway and keep the leaves from falling the first place, with an investment of £49m between now and 2024.”
Why the delay because of a leaves?
As a train travels along a track littered with leaves, it compresses them, and they turn into a slippery gel-like substance which in this state has the same effect has what black ice does on the road. When a Train slows down if the track is not treated the train will not have the required grip and will slide along the track in the railway equivalent of a car locking its wheels up.
This can lead to station overruns or much worst signals passed and danger (SPADS). However, drivers are trained to deal with different track conditions such as this and know where the hotspots are as well as how much braking power they can safely apply with the least amount of wheel-slide as possible.
Modern-day trains are also fitted with wheel slide protection systems (WSP) which is the railway version of ABS. It can detect a wheel (or axle) that is slipping or sliding and can automatically release the brake pressure just enough so that the wheels spin again but the train is also braking. All of this is done by an onboard computer and no driver interaction.
Most drivers are advised in training that once they have started braking if they see that the train is slipping or sliding to let the WSP do its job and do not try and fight it by selecting a different brake setting. If they can see they will not stop at the station or signal in time, then they are then advised to select the emergency brakes and bring the train to a complete stand.
This is where delays start happening as drivers need to start slowing down much sooner than usual due to the fact they are applying less braking power to avoid the above situation happening. When you’re running late for work, it can be annoying to hear that your train is late just because of a few leaves. However, please do remember it is for your safety.