Having recently been travelling around London and hearing an increased noise level as well as the reported (now cancelled) industrial action I wanted to try and better understand the issue of track noise. Obviously most of it comes from the tight bends in the track with elements of the train wheels scraping along the track such as at Bank on the Central line. What I hope to better understand is why is there so much noise on some straight newer sections of track like on the JLE? and what is Pandrol Vanguard track and why is it causing so many issues as I believe its strongly disliked by drivers?
Pandrol Vanguard was introduced as a way of mitigating against the tunnel vibrations being experienced by surface buildings on the alignment of railways. There are several locations in London where if you just put your hand against a wall, you can feel the vibrations of passing trains BBC Broadcasting House (Bakerloo line) and the British Library (Circle, H&C, MET) just to name a few.
Vanguard is supposed to contain those vibrations by means of rubber anchor pads that sit between the rail and the chair. It's often sold as a cheaper alternative to floating track slab which aims to solve a similar problem. The first London Underground installation was on the Victoria Line in 1999, I believe the most recent product trial that went network wide were at Shepherds Bush and Maida Vale.
I think it's important to remember that although the JLE has higher running speeds, it is far from straight. It curves all over the place, just more generously than older lines which is why perhaps from a passenger point of view you don't feel it. Noise has always been an issue there, in fact I'm willing to say that the JLE is quieter now than it was in the early 00's
The track between Finsbury Park and 7 Sisters on the Victoria has become incredibly loud recently. It sounds like a combination of a jet engine taking off and worn wheel bearings screaming. It even drowns out the music on my closed cup headphones when I wear them now.
On a slight tangent the track ride between Finsbury Park and Highbury & Islington is very poor compared to the rest of the line with some violent jolts to one side or another. Whilst I'm sure it's within legal tolerances it can still throw people around in the carriages!
Another day, another bulletin, so many trees sacrificed!
Where does the increase in-tunnel noise come from?
Approximately three years ago, London Underground saw an increase in complaints from residents close to our network as a result of ground-borne noise being experience in people's homes.
Track Engineering identified a solution to reduce nose and vibrations, especially with the introduction of Night Tube.
This solution, Pandrol Vanguard (PV), has delivered a considerable improvement in vibration to the properties of affected residents, and has now been installed in 36 locations across the network.
PV works by lifting the rail off the track bed and supporting it, which prevents the energy generated by the passage of trains being transferred through the ground. However the energy cannot be eliminated completely, and remains present in the tunnel.
To reduce the increase in-tunnel noise levels we are carrying out different engineering solutions across the network including enhanced grinding and PV replacement
Duncan Weir Head of Track, Asset Operations
What we're doing to reduce in-tunnel noise across the network...
We understand the concerns of our train operators and we're taking decisive action across the network to help reduce in tunnel noise.
I'm committed to doing everything we can to resolve the issue and ensure that the Tube is a comfortable environment for our people and our customers.
We have secured additional funding for a number of immediate and longer-term solutions to reduce in-tunnel noise.
Longer term solutions include removing Pandrol Vanguard baseplates, breaking out the current concrete sleepers, replacing them with new wooden ones, fitting Delkor baseplates and then replacing the rail, which then needs to be aligned.
Immediate solutions include a range of ear defenders available from your depot admin.
We remain fully committed to finding practical and viable ways of further reducing noise levels on the Underground. I will keep you updated as we progress with this work
Nick Dent Director of Line Operations.
Deklor is a new noise reduction solution. We are currently installing and trialing Delkor baseplates on the Jubilee Line between Baker Street and St' John's Wood
Installation of soft pads which are placed between the Pandrol Vanguard pads and sleepers to dampen the noise. They have shown a noise reduction of between 3 and 5dB, and changed the frequency to a less sharp one.
The implementation of an enhanced programme of rail grinding which triples the level of grinding at prioritised sites. This has already been completed on the Victoria line, with readings from across the line indicating a positive reduction in noise levels experienced.
Apart from needing spellchecker (trialling has two Ls) both of these gentlemen deserve a copy of "Eats, shoots and leaves" for Christmas for their inappropriate over use of commas. Pedantic, moi?