Air Flow to Coaches in Tunnels.

[Envoy]

Modern cars have a feature whereby when in traffic jams, the air system can be switched from sucking in external air to re-circulating air to prevent pollution entering the vehicle. Do trains have a similar feature and if so, do drivers use it?

(I have smelt diesel fumes when in tunnels although on HST’s, I suspect that much of this enters through door windows left open. It is regrettable that Box tunnel between Chippenham & Bath has the electric conductor rail but will not be linked to the electric system for some time. It is also regrettable that apart from London trains, the Severn tunnel will still have an entirely diesel fleet going through it. I just hope that the Turbos will have their windows closed and a working air-con system in operation).

 

[coppercapped]

Modern cars have a feature whereby when in traffic jams, the air system can be switched from sucking in external air to re-circulating air to prevent pollution entering the vehicle. Do trains have a similar feature and if so, do drivers use it?

(I have smelt diesel fumes when in tunnels although on HST’s, I suspect that much of this enters through door windows left open. It is regrettable that Box tunnel between Chippenham & Bath has the electric conductor rail but will not be linked to the electric system for some time. It is also regrettable that apart from London trains, the Severn tunnel will still have an entirely diesel fleet going through it. I just hope that the Turbos will have their windows closed and a working air-con system in operation).

Wimp!

You should have gone through the Severn Tunnel in steam days...

...what's the matter with young folk today?

 

[randyrippley]

Conductor rail?

 

[pdq]

On 185s the A/C fans automatically switch off and back on while going through Standedge Tunnel.

 

[BrunswickGreen]

Wimp!

You should have gone through the Severn Tunnel in steam days...

...what's the matter with young folk today?

In fact in those days it was almost compulsory to make sure the train windows were open when entering a tunnel (different times). Travelling between Gt. Malvern and Hereford was a particular favourite route.

 

[sprinterguy]

Conductor rail?

Yep, in place of the more common wire based overhead catenary; installed due to limited clearances in tunnels such as Severn and Box, amongst others (Example within Stanton Tunnel on the Old Dalby test track pictured below).

There's some more information on the Great Western installation of overhead conductor rails here:
https://www.railengineer.uk/2016/07/11/developing-rocs-for-the-uk/

 

[randyrippley]

Yep, in place of the more common wire based overhead catenary; installed due to limited clearances in tunnels such as Severn and Box, amongst others (Example within Stanton Tunnel on the Old Dalby test track pictured below).

There's some more information on the Great Western installation of overhead conductor rails here:
https://www.railengineer.uk/2016/07/11/developing-rocs-for-the-uk/

thanks, I didn't realise they were using that
I assumed the poster was referring to 3rd rail.......

 

[sprinterguy]

thanks, I didn't realise they were using that
I assumed the poster was referring to 3rd rail.......

Yes, it took me a little moment to work it out before my brain caught up with what I was reading, too.

 

[rebmcr]

installed due to limited clearances in tunnels

I believe a while back, when discussing the St Pancras Low Level installation of Rigid Overhead Conductor, one of the electrification engineers on here confirmed that it does not offer any enhanced clearance, but is instead justified on the massive reduction in maintenance requirements.

 

[sprinterguy]

I believe a while back, when discussing the St Pancras Low Level installation of Rigid Overhead Conductor, one of the electrification engineers on here confirmed that it does not offer any enhanced clearance, but is instead justified on the massive reduction in maintenance requirements.

Fair enough, though the article I linked to certainly does make the point that it does allow for electrification in restricted clearances that would otherwise prove difficult.

 

[DelW]

I believe a while back, when discussing the St Pancras Low Level installation of Rigid Overhead Conductor, one of the electrification engineers on here confirmed that it does not offer any enhanced clearance, but is instead justified on the massive reduction in maintenance requirements.

To be pedantic, a rigid conductor rail would need less vertical space than a catenary cable would, since that has the form of a vertical curve. it would be possible to fix a conductor wire to the tunnel roof without a catenary cable, on a similar alignment to the conductor rail, but that would need more closely spaced supports, which might be a part of the difference in maintenance requirements mentioned.

 

[route:oxford]

Should try the "Weegie stink" on the way into Glasgow Queen Street. It's utterly bouffin.

 

[380101]

Should try the "Weegie stink" on the way into Glasgow Queen Street. It's utterly bouffin.

It'll be less "stinky" come December for a wee while. Then it'll be worse again once the HSTs enter Scotrail service.

 

[Bald Rick]

I believe a while back, when discussing the St Pancras Low Level installation of Rigid Overhead Conductor, one of the electrification engineers on here confirmed that it does not offer any enhanced clearance, but is instead justified on the massive reduction in maintenance requirements.

And reliability. It will take a big whack to make it fall down!

 

[gimmea50anyday]

On 185s the A/C fans automatically switch off and back on while going through Standedge Tunnel.

Do they? Thats news to me....

Expect you are thinking of Eco mode. One of the engines shuts down when no longer required. Usually once up to speed on the ECML or at the top of the hills. York to scarborough and occy road to liverpool are also often run on eco 2 as the high power isnt needed. It takes a few seconds for the auxiliary power to switch from the shut down engine to crossfeed from one of the remaining running engines and its this power switching that shuts down the HVAC momentarily. Eco often kicks in in standedge as when the train emerges from the other end of the tunnel its down hill all the way to stalybridge or Dewsbury so the traction power isnt needed!

Crossfeed - when one engine is supplying auxiliary power to two coaches. You can tell which engine is cross feeding as the RPM of the engine will be running at 998 instead of 847 when idling.

 

[pdq]

Do they? Thats news to me....

Expect you are thinking of Eco mode.

I'm pretty sure about this, having commuted to Manchester between 2010 and 2015. The ac fans go off at Marsden and come back on at Diggle - and vice versa. It's always at the same place so is controlled, I assume, by GPS.
I remember once we got held for 20 mins or so at the last signal before the tunnel eastbound, just after the A/C had gone off. By the time we got moving the temp and air quality were both pretty unpleasant, but recovered at Marsden.

 

[edwin_m]

395s close the aircon intakes when entering tunnels on HS1. I think this is to reduce the pressure pulse inside the train, and they may re-open when within the tunnel - it probably isn't to do with diesel fumes!

 

[pompeyfan]

Going through Southampton tunnel in a Desiro when an older 66 is passing through is similarly unpleasant... although going through Southampton in general is also unpleasant

 

[DarloRich]

Crossfeed - when one engine is supplying auxiliary power to two coaches. You can tell which engine is cross feeding as the RPM of the engine will be running at 998 instead of 847 when idling.

Ah so it is 998 revolutions. I only managed to count 996

Modern cars have a feature whereby when in traffic jams, the air system can be switched from sucking in external air to re-circulating air to prevent pollution entering the vehicle. Do trains have a similar feature and if so, do drivers use it?

(I have smelt diesel fumes when in tunnels although on HST’s, I suspect that much of this enters through door windows left open. It is regrettable that Box tunnel between Chippenham & Bath has the electric conductor rail but will not be linked to the electric system for some time. It is also regrettable that apart from London trains, the Severn tunnel will still have an entirely diesel fleet going through it. I just hope that the Turbos will have their windows closed and a working air-con system in operation).

Should have tried Sunderland station when a 56 was starting a long coal train away. Kids today!

 

[gimmea50anyday]

Ah so it is 998 revolutions. I only managed to count 996

Thats what it says on the TMS anyway...

 

[DarloRich]

Thats what it says on the TMS anyway...

it is fairly obvious, form a passengers point of view, when the system has gone into eco mode. mainly because the carriage is often very quiet. It seems a very good idea!

 

[gimmea50anyday]

When you havent got a QSK19 purring away underneath the carriage it does make quite a difference to the "ambiance" of the train. I am amazed how the same engine sounds completely different on a 185 to a voyager or a 180

If you like your thrash, From a staff members point of view centre cabs of a 6 car bowling thru standedge with all 6 engines at full bore does sound pretty immense!!! FULL POWER NOW SIR!!! XD

 

[tsr]

When you havent got a QSK19 purring away underneath the carriage it does make quite a difference to the "ambiance" of the train. I am amazed how the same engine sounds completely different on a 185 to a voyager or a 180

If you like your thrash, From a staff members point of view centre cabs of a 6 car bowling thru standedge with all 6 engines at full bore does sound pretty immense!!! FULL POWER NOW SIR!!! XD

Soft. We have 10 coach diesels down here.

No major fume intake in the tunnels on the Uckfield either. (Class 171 HVAC tends not to actually do anything noticeable anyway, so the chances of it drawing in diesel fumes are not too high!)

 

[Envoy]

395s close the aircon intakes when entering tunnels on HS1. I think this is to reduce the pressure pulse inside the train, and they may re-open when within the tunnel - it probably isn't to do with diesel fumes!

That’s interesting. I note that when going through single bore tunnels in particular, that air pressure on the ears can be very uncomfortable. The Dinmore tunnel on The Marches comes to mind though I have also encountered this on the twin track Chipping Sodbury tunnel.

 

[dk1]

I quite enjoying following a filthy diesel into Ipswich tunnel when it's a thick smog. People are far too worried about their lungs these days

 

[Master29]

I quite enjoying following a filthy diesel into Ipswich tunnel when it's a thick smog. People are far too worried about their lungs these days

Says he on 40 a day. Wouldn`t do me much good now at my age but was great wafting in all those fumes at both Liverpool Street and Paddington when I was younger. I`m asthmatic too. Nowadays I spend most of the time in tunnels stopping the blocking sensation in my ears.