Excessive noise in tunnels

Having travelled at least four weekdays a week during 2020 and 2021 on the jubilee between Westminster or Green Park and Canary Wharf, i can say the sound levels between London Bridge and Canary Wharf seemed to rise after last December, particularly between Canada Water and Canary Wharf. Similar to an earlier post, I’ve also changed my headwear. Have gone from in-ear automatic noise cancelling (anc) ones to over ear anc headphones.

Have they even tried to ameliorate the problem by adding something sound absorbent to the tunnel walls?

Some tunnels used to have absorbent sheeting - the Northern line in the Hampstead area was one. However, the absorbent material was also hazardous (it was Asbestos).

Yes, I do seem to remember that very loud noise as it exited the tunnel, thankfully that has gone!! Not sure if that has something to do with track maintenance though

Where this was done (albeit not CBTC and not because of track noise) was on the westbound entry to the tunnels shortly after leaving Leyton station.

Previously when an accelerating train which also took advantage of the descent entered the tunnel it would be going fast enough to make one's ears go 'pop' because of the changes to the air pressure. I miss this!

Whether they have rail ground or not, most of the Central line between Shepherds Bush and St Paul’s was appalling yesterday.

<<Post merged from 'Tube Noise/quiet sections' thread within General Questions and Comments - goldenarrow>> 

Just after our family acquired a TV, Granada had a weekly programme "All our yesterdays", featuring cinema newsreels from 25 years previously (i.e 1935-6-7).
One item covered, interesting to a young railway enthusiast, was the innovation of "Quiet Sections" on LPTB railways, c 1936, and featured a car of what I subsequently thought was probably 1935 stock, and a handsome couple shouting [because of ambient tube noise] sweet nothings to each other, and suddenly entering a quiet section to the general amusement of other passengers. I've never found this clip again.
What became of these revolutionary quiet sections?
Has anyone studied what comprises tube noise? A journey out to zone 6 on the Central Line today got me thinking about this - in the tunnel section, apart from track noise (rail/conductor rail joints?), wheel screech, general rattles seemingly emanating from the bogies, there was a squeal and boom from a higher level and from the doors; also a pump of some kind underfloor. Noise in the open sections was much more tolerable, as you would expect, because it could dissipate easily.
Conversation was impossible in the tunnels; and this may be age-related, either per the stock or per the passenger - and not very easy on some of the open sections.
Is it time to re-invent quiet sections?

The Jubilee is worse.

Believe RMT won the battle and staff are now issued with PPE for noise control. While obviously PPE is at the bottom of control measures for risk management at work it is an acceptable short term mitigation while better solutions for these problems can be found - rolling stock with better insulation, replacing clips and perhaps track, etc. Passengers are afforded no such duty of care (though I could see some interesting cases arising, though they drift off topic...).

I have noticed several sections re railed, with new clips, areas being grinned, but the eastern section was grinded in April. (Epping - Loughton points), isn't rail grinding supposed to make the ride smoother (correct me if I'm wrong), but has anyone noticed this area is extremely bouncy?

In the merged thread, I wasn't referring just to *track* noise as does the thread you've merged it into, but also boom from tunnels (is it different eg with steel and concrete), wind/air pressure, and motor/brake system sounds. Is one sort of tube tock noisier than another, for instance?
Is the quiet sections clip on the net, does anyone know? I couldn't find it.

Personally, from my experience, it's better to hear grinder rails then the loud noises in the tunnel... I've noticed bullhead rail is still used underground, do they install this still or are they changing all the bullhead areas to Pandrol clips?

I'm wondering what accounts for the 'long noise' where approaching and receding noise comes through into buildings and above ground (like tubes running above Haverstock or Chalk Farm).

We had a lot of track underpinning (ongoing) but noise occurs in both directions so is it really just a simple case of a rail issue ? e.g. would both tracks be slipping at the same time?

The crew working on it didn't seem surprised to hear its noisy,

The 2021 train noise recordings show a high level (104ish) dB which matches my own platform measurements.

If corrugation is the cause, you'd expect to easily notice differences between the tracks, unless both corrugate at the same rate.

I can't help wondering if the source noise is one thing, but its being amplified by the tunnel for some reason, but that some other effect causes that to wax and wane. As the overall effect, which nobody can explain so far, is the slowness at which noise appears and goes away. e.g. you might get noise for 1-2 days, it hits a crescendo and then drops entirely away for some time - hours or days - then creeps up again over a few hours

This week I observed Monday PM to Tuesday AM very noisy indoors and outside, Tues 2-7 it got a lot quieter and when visiting Wednesday 3-4, it was near silence.....which won't last. The onset or disappearance of the noise is almost like throwing a switch....you can hear it ramp up or ramp down quite markedly within a few trains.  It happens in both directions together usually.

Could the tunnel be changing its ability to contain sound, or some kind of air or groundwater effect be in play?  Are there routines to check to find out if pumps, vent or other mechanical job is coinciding with when it changes?

Passing trains also vibrate paving on chalk farm road quite strongly and thump bass under the Roundhouse which you can hear on its ground floor when its not thumping a gig - or when it is :-D.

I live above the points on the northbound approach to Seven Sisters and yes - it can be exactly as Jonathanburg has described above. There doesn't appear to be any rhyme or reason as to why some days the noise of the trains below are louder than others. Today (10th February 08:30) they are particularly loud.

To add - I have lived here since the last days of the 67 stock. You could barely hear them. 09TS was louder but not excessively so. When the timetable changed to majority through running to Walthamstow there was a substantial increase in noise - the trains run at full speed over the points to Platform 3 but reduce to a much slower approach to Platform 4 for the Seven Sisters Terminators.

A year or so ago there was a speed restriction on the points meaning all trains were slowed on the approach and for a month or two it was blissfully quiet. Just prior to this restriction the sound was the worst I have known it with the house noticeably shaking - so clearly there was a fault with the track/points then.

I'm not complaining - I knew about the trains when I bought the property and it's a trade off for living so close I can be on the platform within 2 minutes of leaving the house - but it's a pity that over the years the noise has got worse due to change of stock and timetable patterns. I did worry when "night tube" came about that my sleep would be affected but the trains are so in-frequent that it wasn't a problem in the end.

In short I would say the quality of all factors of the track and points do affect the noise but why there are such marked differences within hours of each other is a mystery. Temperature may have a bearing perhaps but it would be impossible to keep tunnels at consistently the same perfect temperature 24/7.

I am guessing current rolling stock is heavier than the ones of the past and this also affects the infrastructure beneath the wheels - but overall speed is probably the main issue. you can either have optimum speed for reducing sound issues or optimum speed for timetable operation. it would be a miracle if they both could be the same. (I didn't notice any issues with the timetable when they reduced the approach speed to Seven Sisters the other year!) and of course each tunnel and even sections of tunnel have their own unique profile which affects overall sound harmonics which can amplify any given sound due to that particular set of characteristics at that location so again to have a constantly changing speed profile adjusting to short sections of tunnel is also impractical.

I must also add that NR recently replaced the overground track through the station on the viaduct and over the road bridge. You can barely hear the overground trains at all now - even the late night expresses that get diverted through 7 sisters instead of the Lea Valley line barely register now whereas before the house would shake as they passed. So good track and ballast is definitely key.

Customer service suggest so, but I don't think they communicate with technical folk 100% well, if so it will be a partial story in/partial diagnosis out.

Another thought is whether track lubrication systems fire on a set schedule or simply need to oil things a little more often.