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Post by will on Oct 14, 2019 21:44:59 GMT
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? Thanks  |
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Post by goldenarrow on Oct 15, 2019 13:13:11 GMT
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
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Post by cudsn15 on Oct 15, 2019 13:57:38 GMT
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!
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Post by aslefshrugged on Oct 30, 2019 8:49:33 GMT
Another day, another bulletin, so many trees sacrificed!
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?
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Post by trog on Jan 6, 2020 20:13:58 GMT
Rail grinding could suggest a rail corrugation problem, where migration of the steel on the running table of the rail leads to a series of high and low spots on the rail head each only an inch or two long. Such rails were not referred to as roaring rails for nothing.
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Post by 100andthirty on Jan 7, 2020 17:56:44 GMT
Configuration is a wear issue. Vibration causes the load on the rail to vary in a cyclic way and its the high load places that see wear, developing low spots, compared with the low load high spots. Some of the techniques used to reduce noise into the infrastructure can promote corrugation if the spring rates of the track supports promote some sort of resonance with the train's suspension. The treatment is rail grinding, the cure is to set our the resonance.
Similar effects occur on curves where the outside wheel is trying to rotate faster than the inside wheel - beyond what can be resolved with the coned wheel profile - and a stick/slip action happens to resolve the speed discrepancy and this leads to corrugation.
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bigvern
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Post by bigvern on Jan 8, 2020 17:01:34 GMT
The train bogies also play a factor in wheel/rail noise as some bogies rotate from a centre pivot which gives better wear, and some bogies are a split frame with an offset pivot which is better in some track conditions but not significantly on curved track as the Northern 95s and Victoria 09s have the same split frame bogie and rail corrugation on curves is more evident.
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Post by zbang on Jan 8, 2020 17:56:51 GMT
BTW, the February 2020 Trains Magazine (USA-centric) has a nice article titled "Fighting rail wear", recommended if you can get your hands on it.
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Post by Chris L on Jan 8, 2020 20:45:36 GMT
The Jubilee line noise seems to be coming from the flange of the wheel against the track.
It is not down to individual trains. It is consistent for the same stretch every time.
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rincew1nd
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Post by rincew1nd on Jan 8, 2020 21:53:55 GMT
It's seems to me like there are three types of track noise: - Flange squeal: a high pitch noise caused by the flanges rubbing against the rail head on curves, often low speed.
- Corner grumble: a low pitch noise caused by the treads on both ends of a fixed axle being forced to travel at the same speed in a corner - one wheel has to slip slightly along the rail head.
- Track noise: A variety of pitches resulting from a more complex interaction generated in the rails and their fixings.
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Post by grumpycat on May 18, 2020 16:55:32 GMT
at Camden town-euston on the northern line (bank branch) it is evident when the last few times I went on it my ears came out ringing however a few ago it was quiet seems it is one if the contenders
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Post by jimbo on May 18, 2020 19:32:38 GMT
From a recent Underground News: TfL Customer Service Operational and Performance Panel met on 27 February 2020 to hear a paper on Noise on Public Transport. It reported that Pandrol Vanguard (PV) is an engineering solution that has reduced ground-borne noise experienced by residents in close proximity to certain parts of the LU network. However, an unintended consequence of PV has been to increase in-carriage noise, which has affected both customers and Train Operators in some locations. Given the drawbacks of PV, TfL are looking for alternative ways of reducing ground borne vibrations without significantly increasing the level of airborne noise, and are currently exploring alternatives to PV, including the testing of alternative Delkor rail fastenings at Baker Street. Similarly, tuned mass dampers fitted to rail feet, designed to reduce vibration and the rate of rail corrugation growth, have yielded positive initial test results, and a larger trial is planned for mid-2020. Tube drivers have also been offered ear protection in the interim. A map of hotspots highlights the Jubilee line west of Baker Street and north of Green Park, the Northern line around Mornington Crescent and the Kennington loop, the Piccadilly line east of South Kensington, the Central line around Holland Park and west of Bethnal Green, the Victoria line west of Highbury & Islington, west of Warren Street, and north of Pimlico, and the sub-surface lines between Moorgate and Barbican. See: content.tfl.gov.uk/csopp-20200227-public-agenda-pack.pdf |
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Post by John Tuthill on May 18, 2020 20:10:09 GMT
From a recent Underground News: TfL Customer Service Operational and Performance Panel met on 27 February 2020 to hear a paper on Noise on Public Transport. It reported that Pandrol Vanguard (PV) is an engineering solution that has reduced ground-borne noise experienced by residents in close proximity to certain parts of the LU network. However, an unintended consequence of PV has been to increase in-carriage noise, which has affected both customers and Train Operators in some locations. Given the drawbacks of PV, TfL are looking for alternative ways of reducing ground borne vibrations without significantly increasing the level of airborne noise, and are currently exploring alternatives to PV, including the testing of alternative Delkor rail fastenings at Baker Street. Similarly, tuned mass dampers fitted to rail feet, designed to reduce vibration and the rate of rail corrugation growth, have yielded positive initial test results, and a larger trial is planned for mid-2020. Tube drivers have also been offered ear protection in the interim. A map of hotspots highlights the Jubilee line west of Baker Street and north of Green Park, the Northern line around Mornington Crescent and the Kennington loop, the Piccadilly line east of South Kensington, the Central line around Holland Park and west of Bethnal Green, the Victoria line west of Highbury & Islington, west of Warren Street, and north of Pimlico, and the sub-surface lines between Moorgate and Barbican. Thank you for that, very illuminating. Is there any information regarding 'reflective noise' between Jarra wood and concrete sleepers? |
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Post by xtmw on Mar 31, 2022 10:49:44 GMT
<< Thread merged from 'Pandrol clips' thread in General Questions & Comments - goldenarrow >>I've noticed in sections that have been re-railed, they seem to use a new form of pandrol clip? Correct me if I am wrong, but is this new? Are LU not happy with the other pandrols which have been keeping the rails to the sleepers for years now? Image attached.  Another thing I've noticed is that they aren't used in tunnel sections? Why is this? Once again, correct me if I'm wrong. Thanks all! I am new to this form and not all that experienced with railways!!!
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class411
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Post by class411 on Mar 31, 2022 11:42:44 GMT
Could it be something to do with noise suppression?
There appears to be some plastic involved.
Avoiding some metal to metal contact could cut down noise transmission considerably.
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Post by Dstock7080 on Mar 31, 2022 11:54:33 GMT
I've noticed in sections that have been re-railed, they seem to use a new form of pandrol clip? Correct me if I am wrong, but is this new? Are LU not happy with the other pandrols which have been keeping the rails to the sleepers for years now? Image attached. Another thing I've noticed is that they aren't used in tunnel sections? Why is this? Once again, correct me if I'm wrong. Thanks all! I am new to this form and not all that experienced with railways!!! Reading the Pandrol website: Fastclip Baseplate are for use on ballasted track. |
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Post by xtmw on Mar 31, 2022 13:26:11 GMT
Could it be something to do with noise suppression? There appears to be some plastic involved. Avoiding some metal to metal contact could cut down noise transmission considerably. On the subject of noise suppression, it something LU needs badly as I was on many tube lines yesterday and it was getting very, very loud in some areas! Isn't the Pandrol Vanguard supposed to combat this or is that for noise and vibration for nearby residents? |
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Post by Deleted on Mar 31, 2022 20:41:42 GMT
They also have rubber pads installed under rail chairs in some places to try and reduce noise
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Post by goldenarrow on Apr 1, 2022 10:41:50 GMT
Could it be something to do with noise suppression? There appears to be some plastic involved. Avoiding some metal to metal contact could cut down noise transmission considerably. On the subject of noise suppression, it something LU needs badly as I was on many tube lines yesterday and it was getting very, very loud in some areas! Isn't the Pandrol Vanguard supposed to combat this or is that for noise and vibration for nearby residents? One of the primary goals of Pandrol Vanguard was to reduce noise/vibration seepage to surrounding buildings, something given added importance with Night Tube. Whilst it was successful in that regard, its had the notable side-effect of increasing noise levels in the tunnels themselves. It is currently installed across 40 locations on the Central, Jubilee, Northern, Piccadilly and Victoria lines. |
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Post by sealingmark on Apr 1, 2022 14:41:58 GMT
<< Merged from the 'High levels of wheel-screeching noise' thread in General Questions & Comments - goldenarrow >>Mentioned in passing on another thread… This really is painfully loud on some lines. Unbelievably loud. Poor bloody driver who is subject to that all shift. Jubilee south from Green Park to Canning Town had some examples. The return journey was much worse (similar volume but occurred for more of the run). Victoria line between Victoria and Brixton does it too. Never encountered any such wheel-screeching on the Pic, District or Central. What’s the cause? Any remediation ever likely?
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Tom
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Post by Tom on Apr 1, 2022 16:39:19 GMT
There's been a lot of discussion about wheel/rail noise here, I'm guessing this is more 'roaring rails' rather than squealing like you get on tight curves, based on the lines/sites you've listed? |
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Post by johnlinford on Apr 2, 2022 9:12:15 GMT
I've (for obvious reasons) only been an occasional user in the last couple of years, but it certainly seems a lot louder between Canning Town and Green Park than it used to - despite my noise cancelling headphones getting better!
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Post by xtmw on Apr 4, 2022 9:43:54 GMT
I've (for obvious reasons) only been an occasional user in the last couple of years, but it certainly seems a lot louder between Canning Town and Green Park than it used to - despite my noise cancelling headphones getting better! I've been scrolling through threads and it seems rail grinding helps a lot with this noise. It's certainly better to hear a high pitched noise, which is relatively quiet and can't be heard through noise cancelling headphones, then a loud tunnel 'scream'. TfL should definitely start looking into this more. |
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rincew1nd
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Post by rincew1nd on Apr 5, 2022 12:31:29 GMT
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Post by xtmw on Apr 5, 2022 14:32:13 GMT
That is loud! I was wondering did anyone have a list for the loudest lines when track improvement works/rail grinding will be taking place? |
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hobbayne
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Post by hobbayne on Apr 6, 2022 10:33:46 GMT
I clocked 105db between Stratford and Leyton EB. Its no wonder why there are quite a few drivers failing the medical with hearing problems.
Several have already been fitted with hearing aids.
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Post by xtmw on Apr 6, 2022 12:29:07 GMT
I clocked 105db between Stratford and Leyton EB. Its no wonder why there are quite a few drivers failing the medical with hearing problems. Several have already been fitted with hearing aids. That's one of the worse bits! When I commute, I have to do that when I come back. Again, this is the sections with the tunnel 'scream'. I did in fact write to TfL but they just replied back saying they are committed to the passengers safety etc.. |
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hobbayne
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Post by hobbayne on Apr 6, 2022 13:20:11 GMT
Ah yes. The cut and paste reply that covers everything.
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Post by alpinejohn on Apr 6, 2022 14:12:24 GMT
I clocked 105db between Stratford and Leyton EB. Its no wonder why there are quite a few drivers failing the medical with hearing problems. Several have already been fitted with hearing aids. Hmm so that seems roughly similar to the sound level you might encounter operating a typical electric drill without any ear defenders.? Having commuted for decades I have no doubt the noise is loud but you do not state what "device" or "approved software" you are using to assess the decibels. As this link explains.. www.safetynewsalert.com/do-smartphone-apps-provide-accurate-noise-measurement/There are no android apps which have been certified as accurate, and only a couple of costly iphone apps which have been tested to deliver reasonably accurate noise level assessments. Likewise it would be interesting to know where and why the operator chose to take their video from. I can easily locate several places where there are high sound levels in my VW car if I was to place my iphone right beside the rubber door seal. However if I moved the phone just a few inches away from the door seal then the monitored noise level is substantially lower. Likewise sound levels can be massively higher if the windows are open rather than closed. Another factor to consider is that the generally poor quality of audio pickups installed in most mobile phones which means that many videos produce rather misleading audio especially when compared with real life. This has been remarked upon in several railway related youtube videos. For instance the early videos of the Class 230 battery demonstrator suggested the unit was producing an almost unbearable unpleasant high pitched whining noise as it accellerated, however this was not just observed with my own ears. I suspect that most regular commuters already know the places where their route is noisy, and they probably do not go out of their way to stick their ear right beside the door seal. Indeed many seem largely isolated from the planet, often wearing noise cancelling headphones whilst immersed in a movie on their mobile device. My guess is that most commuters actually choose to sit or stand well clear of the doors and areas where the most extreme noise levels are present. |
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class411
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Post by class411 on Apr 6, 2022 15:42:45 GMT
I clocked 105db between Stratford and Leyton EB. Its no wonder why there are quite a few drivers failing the medical with hearing problems. Several have already been fitted with hearing aids. Hmm so that seems roughly similar to the sound level you might encounter operating a typical electric drill without any ear defenders.? Having commuted for decades I have no doubt the noise is loud but you do not state what "device" or "approved software" you are using to assess the decibels. As this link explains.. www.safetynewsalert.com/do-smartphone-apps-provide-accurate-noise-measurement/There are no android apps which have been certified as accurate, and only a couple of costly iphone apps which have been tested to deliver reasonably accurate noise level assessments. Likewise it would be interesting to know where and why the operator chose to take their video from. I can easily locate several places where there are high sound levels in my VW car if I was to place my iphone right beside the rubber door seal. However if I moved the phone just a few inches away from the door seal then the monitored noise level is substantially lower. Likewise sound levels can be massively higher if the windows are open rather than closed. Another factor to consider is that the generally poor quality of audio pickups installed in most mobile phones which means that many videos produce rather misleading audio especially when compared with real life. This has been remarked upon in several railway related youtube videos. For instance the early videos of the Class 230 battery demonstrator suggested the unit was producing an almost unbearable unpleasant high pitched whining noise as it accellerated, however this was not just observed with my own ears. I suspect that most regular commuters already know the places where their route is noisy, and they probably do not go out of their way to stick their ear right beside the door seal. Indeed many seem largely isolated from the planet, often wearing noise cancelling headphones whilst immersed in a movie on their mobile device. My guess is that most commuters actually choose to sit or stand well clear of the doors and areas where the most extreme noise levels are present. Whenever. I travel on the Victoria line, North of Kings Cross, there are passengers ramming their hands against their ears to defend themselves against the appalling noise. No phones or properly calibrated audiometers are required to note the extreme sound levels. |
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