Comparison of Class 68 noise levels with other locomotives

[sjpowermac]

Moderator note: Split from https://www.railforums.co.uk/threads/tpe-mark-5a-coaching-stock-progress.143579/page-180

I can see that ‘Noisegate’ is gathering some momentum so here are a few stats, all in dBA min/max

Class 91
64.4/97.5
(Stood in station/powered up)

Class 68
(engine idling/engine powered up)
82.4/93.8

Class 37
(engine idling/engine powered up)
72.9/100.4

All recordings made from the yellow line on the platform.

Yes, the 68s are loud, but far from dangerous. It takes 120 dBA to damage hearing. So, enjoy, it’s all perfectly safe. The sound as an 802 clattered into the platform was over 100dBA, the wheel/rail interface on a curve produces more noise than a Class 68 on full power.

 

[Meerkat]

How an earth is an idling 68 significantly noisier than a 37 that is decades older?!?

 

[sjpowermac]

How an earth is an idling 68 significantly noisier than a 37 that is decades older?!?

I stood right next to the noisiest part of the 68 so that I couldn’t be accused of ‘cheating’.

With the 37 the sound varied between 72.9 when stood next to the cab, 90 plus when stood in a comparable position right next to the engine.

 

[Erniescooper]

How an earth is an idling 68 significantly noisier than a 37 that is decades older?!?

Because the 68 isn’t idling, it increases engine speed to 1100 rpm to supply the 300 Kw of electrical power the coaches need

 

[sjpowermac]

Because the 68 isn’t idling, it increases engine speed to 1100 rpm to supply the 300 Kw of electrical power the coaches need

That is a very good point.

 

[Ben Bow]

......

Yes, the 68s are loud, but far from dangerous. It takes 120 dBA to damage hearing. So, enjoy, it’s all perfectly safe. The sound as an 802 clattered into the platform was over 100dBA, the wheel/rail interface on a curve produces more noise than a Class 68 on full power.....

I'm afraid it's not quite as simple as that. Whilst 120dBA may damage hearing instantaneously, for lower amounts of noise it depends on the length of exposure to that noise. So 2 hours at 100dBA is worse than 5 minutes at 110dBA. There is a noise 'calculator' on the government's health & safety website. In particular employers need to know what their employees are being exposed to. In the long run, once all sets are in service, I would suggest that at places such as Manchester Victoria with 4 departures per hour, some mitigating measures will be introduced.

 

[Bletchleyite]

I would suggest that at places such as Manchester Victoria with 4 departures per hour, some mitigating measures will be introduced.

Ideally a way to allow the engine to be stopped and the coaches to run on battery for a short period. It isn't just noise, it's also diesel muck in your lungs - Birmingham New St is terrible for it, and as the bit of Manchester Vic under the Arena is very similar in terms of ceiling height and (lack of) ventilation it can easily be as bad.

 

[EE Andy b1]

Slightly going off topic, but about the noise.

Just have a watch and listen of this YouTube video.

I myself have been to Chicago on these Metra trains into Ogilvie Transportation Center, and it is the nosiest train station i have ever been to, anywhere!
All those diesel locomotives are running at high RPMs continually to provide Head End Power (HEP), equivalent to our Electric Train Supply for the coaches.

Maybe this is what stations like Lime Street, Man Victoria and the like have got to look forward to... In a smaller way of coarse!!

 

[Richard Scott]

Slightly going off topic, but about the noise.

Just have a watch and listen of this YouTube video.

I myself have been to Chicago on these Metra trains into Ogilvie Transportation Center, and it is the nosiest train station i have ever been to, anywhere!
All those diesel locomotives are running at high RPMs continually to provide Head End Power (HEP), equivalent to our Electric Train Supply for the coaches.

Maybe this is what stations like Lime Street, Man Victoria and the like have got to look forward to... In a smaller way of coarse!!

Think the old SNCF 72100s could give those a run for their money, they were unbelievably loud on idle, especially with ETS (or whatever French call it) on. 68s not in same ball park!

 

[LNW-GW Joint]

I stood right next to the noisiest part of the 68 so that I couldn’t be accused of ‘cheating’.
With the 37 the sound varied between 72.9 when stood next to the cab, 90 plus when stood in a comparable position right next to the engine.

It isn't just the volume.
The tone of the loco sound is rather whiney, almost a screech.
It's quite different to a rumbling Sulzer or EE engine when they are idling.
And all magnified by the barrel-shaped roofs of Lime St's two big sheds.
The Nova 3 was parked in P1 on the far side of the north shed during its turnround, and the noise was still penetrating (ie making station announcements hard to hear) over by P10 in the south shed.

 

[FFFC 57]

Of course engines are loud there is an explosion happening every other stroke of the crankshaft multiplied by 12 and in two strokes every stroke is a power stroke.

 

[GrimShady]

In the 68s case isn't it the fans that cause most of the noise?

EMD locos have always been the loudest sounding plus they have an annoying whine compared to older British types. I always found Sulzers fairly quiet followed by EE.

 

[FFFC 57]

In the 68s case isn't it the fans that cause most of the noise?

I EMD locos have always been the loudest sounding plus they have an annoying whine compared to older British types. I always found Sulzers fairly quiet followed by EE.

Six cylinder Sulzers are very soothing.

 

[sjpowermac]

It isn't just the volume.
The tone of the loco sound is rather whiney, almost a screech.
It's quite different to a rumbling Sulzer or EE engine when they are idling.
And all magnified by the barrel-shaped roofs of Lime St's two big sheds.
The Nova 3 was parked in P1 on the far side of the north shed during its turnround, and the noise was still penetrating (ie making station announcements hard to hear) over by P10 in the south shed.

Do you have any figures to support your claims? I’ve put some numbers to my claims, you’ve replied with value judgments. If we are talking value judgements, ‘I like the sound’.

If you have a sensible idea for how to measure ‘screech’ and I’ll have a go...

 

[ac6000cw]

Of course engines are loud there is an explosion happening every other stroke of the crankshaft multiplied by 12 and in two strokes every stroke is a power stroke.

I think you are getting confused between piston strokes and crankshaft revolutions.

A 'stroke' is a single traverse of the cylinder by the piston, so each revolution of the crankshaft corresponds to two piston strokes - one up, one down (up = away from the crankshaft).

Hence in a '4-stroke' engine the strokes are: intake (down), compression (up), power (down), exhaust (up) - so the whole cycle takes two crankshaft revolutions.

In a '2-stroke' diesel (simplistically) the power and exhaust operations are combined into one (down) stroke, intake and compression into the other (up) stroke. The intake air has to be driven into the cylinder under pressure as it can't suck it in like a 4-stroke can - hence '2-stroke' diesels normally have a supercharger or hybrid supercharger/turbocharger arrangement to do this.

 

[ac6000cw]

It isn't just the volume.
The tone of the loco sound is rather whiney, almost a screech.
It's quite different to a rumbling Sulzer or EE engine when they are idling.
And all magnified by the barrel-shaped roofs of Lime St's two big sheds.
The Nova 3 was parked in P1 on the far side of the north shed during its turnround, and the noise was still penetrating (ie making station announcements hard to hear) over by P10 in the south shed.

I actually find the 68's quite 'bassy' (not 'screechy'). Because of that they can be a bit 'battering wall of sound' sometimes. To me, it's a typical big V-form high-speed diesel 'loud humming' noise, not so different to an EMD engine of similar power and configuration (1800 rpm 4-stroke versus 900 rpm 2-stroke, so a similar frequency of explosions...)

 

[LNW-GW Joint]

Do you have any figures to support your claims? I’ve put some numbers to my claims, you’ve replied with value judgments. If we are talking value judgements, ‘I like the sound’.
If you have a sensible idea for how to measure ‘screech’ and I’ll have a go...

I'm a scientist so I understand the desire for measurements.
But this was just an opinion based on my first encounter with a Nova 3 set at Liverpool.
The loco sound has nowhere to go at the concourse end of Lime St, and the majority of waiting passengers are only a short distance away through the barriers.
This is unlike stations with "open" ends as at all other points on the route except Scarborough.
It might be quite different if the loco were at the country end of the station (as it would have been yesterday at Scarborough).
Drowning out PIS announcements is not a good advert (except when it is for see-it-say-it-sorted, of course ).
Other diesel traction is quite noisy when idling too, eg 185s, but they are generally shut down during turnrounds.

 

[ac6000cw]

but they are generally shut down during turnrounds.

Which I think Chiltern do at Marylebone with the 68's, as well as putting the locos on the 'country' end of the trains. Might depend whether the MK5s are usable without any ETS supply (lighting, door operation etc.)

 

[Tony2]

There is a separate whining sound, I believe that this is from the traction motors not the diesel engine. On an 88 the whine is exactly the same on electric power only.
Despite this they have to be the most impressive sounding modern locos. I've just heard one that passes my house daily about 500m away. I can hardly hear a 66 pass but always hear a 68 clearly.

It isn't just the volume.
The tone of the loco sound is rather whiney, almost a screech.

 

[DarloRich]

ooooooooooooooh noise, perhaps with associated "clag" and "thrash" - the second favorite enthusiast wibble topic after paint wibble

The answer, as any fule kno, is a Valenta powered HST

 

[ExRes]

Because the 68 isn’t idling, it increases engine speed to 1100 rpm to supply the 300 Kw of electrical power the coaches need

An excellent point and I would love to see the comparable figures for a 67, fortunately I only had around a year of driving them and almost from the word go we were banned from using train supply in the PRDC, we were also told to shut it down at each station calling point because of the complaints due to noise levels

 

[43096]

Hence in a '4-stroke' engine the strokes are: intake (down), compression (up), power (down), exhaust (up) - so the whole cycle takes two crankshaft revolutions.

Or, if you prefer: suck, squeeze, bang, blow.

 

[zn1]

The dear old 92s are a loud bunch of ladies when they are at power...its not always "diesels" that are the bad boys in this debate. ok they dont "pollute" the environment as much but noise wise, i know when they are passing Through Northampton and either entering or Leaving Northampton at the south end of town ...But you cannot NOT love the dear old 37s. Senior citizens who have EARNED the right to be as noisy as they want, they have worked their lives Hard serviing, always love hearing them, along with that unique whiff from their exhaust...English Electric Power at its BEST...

 

[sjpowermac]

I'm a scientist so I understand the desire for measurements.
But this was just an opinion based on my first encounter with a Nova 3 set at Liverpool.
The loco sound has nowhere to go at the concourse end of Lime St, and the majority of waiting passengers are only a short distance away through the barriers.
This is unlike stations with "open" ends as at all other points on the route except Scarborough.
It might be quite different if the loco were at the country end of the station (as it would have been yesterday at Scarborough).
Drowning out PIS announcements is not a good advert (except when it is for see-it-say-it-sorted, of course ).
Other diesel traction is quite noisy when idling too, eg 185s, but they are generally shut down during turnrounds.

Thank you for clarifying that what you wrote is an opinion.

My main aim in showing the figures was to compare the 68 with the Class 91 electrics. The other thing that surprised me was the level of noise over the diamond crossing and curve at the north end of the station, that came in over 100 dBA even for an 802!

 

[Meerkat]

I assume shore supplies are just too much fuss for Liverpool turn around?
Am I right in think they have to be manually attached - no autocouple to buffers sort of job?
So someone has to be competent to get down on the track and you need a process to ensure they don’t forget to disconnect......

 

[sjpowermac]

I assume shore supplies are just too much fuss for Liverpool turn around?
Am I right in think they have to be manually attached - no autocouple to buffers sort of job?
So someone has to be competent to get down on the track and you need a process to ensure they don’t forget to disconnect......

I don’t know but I think you’ve got it right about the amount of fuss for a twenty minute turn around. And why would you do that anyway? I think you would need to prove a clear Health and Safety risk from the noise to go to those lengths.

 

[sjpowermac]

Which I think Chiltern do at Marylebone with the 68's, as well as putting the locos on the 'country' end of the trains. Might depend whether the MK5s are usable without any ETS supply (lighting, door operation etc.)

The 68s I’ve seen at Marylebone are usually in the station for longer that the 20 minute turn around at Liverpool Lime Street. Also, at Marylebone there is a residential area adjacent to the country end of the platforms.

 

[AC47461]

ooooooooooooooh noise, perhaps with associated "clag" and "thrash" - the second favorite enthusiast wibble topic after paint wibble

The answer, as any fule kno, is a Valenta powered HST

As an enthusiast, personally speaking, when it comes to wibble I'd put thrash and noise before paint and clag .....but we're all different

But seriously, I agree, a Valenta powered HST is quite possibly the noisiest train I've ever stood next to went it starts up, and in this case it's the screaming sound more than anything else. I noticed recently how much quieter the re-engined ones are (are the LNER ones MTU? I can't remember).

The other thing I've noticed recently from watching a lot of older videos of 80s traction is just how smoky/claggy/dirty (or however you want to describe them) older diesels really were. I don't remember them like that myself at the time but in every video, everything smokes and clags. In comparison a 68 is a breath of (slighty) fresher air.

I do think the 68s are the best sounding modern diesel, and for this enthusiast, sitting in the ironically positioned quiet coach (1st one behind the loco in a Chiltern set) is quite fun. Having said that I imagine that as we have far fewer diesels locos around these days, the minute we get one that has a bit of noise about it (let's face it, 66s aren't anything like as loud), it does rather stand out. Places like Liverpool Lime St mentioned above or Man Vic, and many others are now home to more electric trains than ever before, or somewhat quieter DMUs and haven't seen diesel loco hauled trains in some time. People will have got used to a lot less noise.

Just my opinion anyway....

 

[Peter0124]

Although not a locomotive it's still worth saying that class 700s in st pancras thameslink can peak between 95 and 110dB when travelling over the curve near the tunnel, measured from the platform

 

[sjpowermac]

Although not a locomotive it's still worth saying that class 700s in st pancras thameslink can peak between 95 and 110dB when travelling over the curve near the tunnel, measured from the platform

That was the thing that surprised me most, the rail/wheel interface can produce far higher noise levels than a diesel locomotive.