DMU's and Full width Corridors between vehicles. Aka s-stock style.

[Darkinsider]

deleted

 

[jopsuk]

I'm not sure why a DMU should be any different. There's probably no regulation that says you can't, I guess there's standards on controlling the spread of fire though? I know there's fuel on board, but part of the key would be "is a modern DMU any more likely to suffer a fault causing a fire"?

 

[a_c_skinner]

Isn't that where the exhaust pipes go? So there isn't room?

I assume the regulations are the same for DMU and EMU.

Andrew

 

[AM9]

Isn't that where the exhaust pipes go? So there isn't room?

I assume the regulations are the same for DMU and EMU.

Andrew

The exhaust pipes could on some designs* go outside the body and outboard of the widened gangway. That would put them outside the fire protected envelope of the passenger area.

Assuming the bulk of the exhaust system that meets current regulations could be accomodated below the solebar. That would leave just a simple pipe to go to the roofline.

 

[Lrd]

They could send the exhaust pipes towards the front and over the cab like this:

 

[Bletchleyite]

Or through the body like on Class 185s and 153s.

 

[47802]

Well the 2 current orders for Northern and Anglia don't really need wide corridor connections, the West Midlands order would be a more likely candidate for them if they are allowed on DMU's

 

[daikilo]

Well the 2 current orders for Northern and Anglia don't really need wide corridor connections, the West Midlands order would be a more likely candidate for them if they are allowed on DMU's

Wide internal corridors are supposed to encourage movement along the train and to enhance the perception of security.

 

[Rob F]

They could send the exhaust pipes towards the front and over the cab like this:

Tricky on an intermediate vehicle without a cab.

Rob

 

[Bletchleyite]

The big downside of them is the inability to move safely to another coach in case of fire/smoke/terrorist attack. This would surely increase the risk of uncontrolled evacuations to the track.

Is a DMU more likely to catch fire than an EMU? I guess so, given the tanks of diesel underneath.

 

[josrey]

Why can they not be directed directly downwards is there a regulation that states they have to go to roof level?

 

[pompeyfan]

Why can they not be directed directly downwards is there a regulation that states they have to go to roof level?

At stations the punters would get covered in fumes rising up from underneath the train, voyagers are bad enough for that, but an actual design doing it is a bad idea.

 

[josrey]

At stations the punters would get covered in fumes rising up from underneath the train, voyagers are bad enough for that, but an actual design doing it is a bad idea.

But surely this is no different to side exiting truck exhaust when you walk down the pavement and there's a truck idling at traffic lights for instance next to you. and surely with modern diesels that should comply to the latest euro emissions standards it wouldn't be too bad also the use of "AdBlue"?

 

[ainsworth74]

But surely this is no different to side exiting truck exhaust when you walk down the pavement and there's a truck idling at traffic lights for instance next to you. and surely with modern diesels that should comply to the latest euro emissions standards it wouldn't be too bad also the use of "AdBlue"?

Considering that walking down a busy fume filled street is hardly ideal I'm not sure why we would try and emulate it on the railway?

 

[josrey]

Considering that walking down a busy fume filled street is hardly ideal I'm not sure why we would try and emulate it on the railway?

I'm not saying emulate it but if you look at some of the locos and DMUs still in use today that are lets face it getting on abit now all with "older" diesel engines that emit tons of "DEEE" (diesel engine exhaust emissions) surely any move to more modern diesel engines which are 85% more efficient than 25 years ago (which is when most of the DMU's I mentioned early hail from) would be better no matter where the exhaust goes?

 

[47802]

Wide internal corridors are supposed to encourage movement along the train and to enhance the perception of security.

I wouldn't dispute that however I expects that's of most benefit to Metro and Suburban stock, where as narrow gangways can offer handy corners to stick Bike Racks non disabled toilets etc, along with exhaust pipes on DMU. I doubt the 195's or the Anglia Bi-modes will have wide corridor connections.

 

[rebmcr]

The big downside of them is the inability to move safely to another coach in case of fire/smoke/terrorist attack.

The aircon (on S stock at least) is designed to circulate on a per-carriage basis, this would prevent a bunch of smoke simply drifting down the train. It's not good enough to provide a barrier seal, of course, but more than enough to mitigate major hazards within the length of a car or two.

 

[Bletchleyite]

The aircon (on S stock at least) is designed to circulate on a per-carriage basis, this would prevent a bunch of smoke simply drifting down the train. It's not good enough to provide a barrier seal, of course, but more than enough to mitigate major hazards within the length of a car or two.

Until the power fails, then you're back where you were.

Not to mention standees being potentially thrown the full length of the train in a collision.

 

[daikilo]

Is a DMU more likely to catch fire than an EMU? I guess so, given the tanks of diesel underneath.

Diesel fuel will not spontaneously ignite other than inside the engine when put under pressure. An EMU however can have e.g. a high-voltage electrical short causing imediate combustion of adjacent parts.

 

[HSTEd]

The exhaust on a Sprinter or most other similar DMUs is not that large.

You can easily have a gangway that has a foot spare on the side for the exhaust, and still look like a pretty much full width gangway from the inside.

 

[Bletchleyite]

Diesel fuel will not spontaneously ignite other than inside the engine when put under pressure.

Or when aerosolised onto something hot.

An EMU however can have e.g. a high-voltage electrical short causing imediate combustion of adjacent parts.

But wouldn't spread very easily as the surrounding materials are mostly either metal or flame retardent.

 

[Astradyne]

Until the power fails, then you're back where you were.

Not to mention standees being potentially thrown the full length of the train in a collision.

Is that any worse than having their head smashed into a solid wall!

 

[LOL The Irony]

The big downside of them is the inability to move safely to another coach in case of fire/smoke/terrorist attack. This would surely increase the risk of uncontrolled evacuations to the track.

Is a DMU more likely to catch fire than an EMU? I guess so, given the tanks of diesel underneath.

Liquid Diesel is really obtuse when it comes to setting it on fire... Look at Ladbroke Grove. The tank had to be crused to catch fire. And they can solve that by using F1/military style kevlar & Carbon fuel tanks.

 

[edwin_m]

Looking closely at the inside of a 700 gangway, some of them in each set have what appear to be sliding doors that are permanently open. I assume these are intended to close if smoke is detected, to prevent it spreading right down the train (but preferably with some means for passengers on the "wrong" side to open them!). If so there's no reason why a DMU couldn't have the same.

 

[Lrd]

Looking closely at the inside of a 700 gangway, some of them in each set have what appear to be sliding doors that are permanently open. I assume these are intended to close if smoke is detected, to prevent it spreading right down the train (but preferably with some means for passengers on the "wrong" side to open them!). If so there's no reason why a DMU couldn't have the same.

I doubt they are automatic though. They are probably there to lock out a carriage if needed (no lights, or bodily fluids everywhere etc)

 

[physics34]

Looking closely at the inside of a 700 gangway, some of them in each set have what appear to be sliding doors that are permanently open. I assume these are intended to close if smoke is detected, to prevent it spreading right down the train (but preferably with some means for passengers on the "wrong" side to open them!). If so there's no reason why a DMU couldn't have the same.

yep there are a few of these. im not sure if there are 2 or 3 in a 12 car set.

 

[Bletchleyite]

Is that any worse than having their head smashed into a solid wall!

More people potentially being thrown further, so yes, it is, for more of them.

 

[Peter Mugridge]

More people potentially being thrown further, so yes, it is, for more of them.

I'd rather risk being thrown further given that I would be losing some momentum before I hit the floor than be hurled into a wall almost immediately.

 

[AM9]

I think that this idea of being thrown the length of a train is somewhat unlikely. For a start, a train in a collision does not stop instantly unless we consider the case of the Moorgate incident on the Northern City line and the foreshortening of the first car to a fraction of its normal length created a deceleratioin curve that increased the survivability of the following cars. An open gangway design wouldn't have made much difference there. To scale that up to a 345/700 event would need a very high speed collision into a solid mass with all lateral movement totally constrained. With the exception of Crossrail, how many single bore tunnels are there where such an event is even remotely likely?
Even if such an even did occur, the rate of deceleration would result on few if any passengers travelling more than a single car's length before hitting the floor and slowing down even quicker. If the trains had any standing passengers, there just wouldn't be room for them to 'fly' between the 2+2 seats, avoiding the vertical grab bars at each set of doors.
I'm sure that to get design safety approval, this type of layout has been cleared in the context of:

a) the probability of such a absolute deceleration in a perfect straight line
b) the probability of passengers, most who would be holding onto a seat back or other grab handle at the time being launched along the centrline of the train
c) the probability of any passengers staying airborne for more than a few metres​

Such approval would have been given elsewhere in Europe and the far-east years ago, well before the UK 'discovered' through open gangwayed rolling stock. I think that the idea of a clear path for even a single human body beyond what already exists has come from the ability to see that far. Just because you can see past the grab bars, accessible toilets etc., it doesn't mean that object as large as a human body would get very far. Imagining that a whole crowd of unfortunate passengers as projectiles barreling through multiple cars is unrealistic and has no bearing on the absolute survivability of even a very rare type of collision.

If anybody is offended by my graphical description above then I apologise in advance, but such practical considerations are part of the safety world that is ultimately designed to protect us.

 

[TRAX]

I think that this idea of being thrown the length of a train is somewhat unlikely. For a start, a train in a collision does not stop instantly unless we consider the case of the Moorgate incident on the Northern City line and the foreshortening of the first car to a fraction of its normal length created a deceleratioin curve that increased the survivability of the following cars. An open gangway design wouldn't have made much difference there. To scale that up to a 345/700 event would need a very high speed collision into a solid mass with all lateral movement totally constrained. With the exception of Crossrail, how many single bore tunnels are there where such an event is even remotely likely?

Even if such an even did occur, the rate of deceleration would result on few if any passengers travelling more than a single car's length before hitting the floor and slowing down even quicker. If the trains had any standing passengers, there just wouldn't be room for them to 'fly' between the 2+2 seats, avoiding the vertical grab bars at each set of doors.

I'm sure that to get design safety approval, this type of layout has been cleared in the context of:

a) the probability of such a absolute deceleration in a perfect straight line

b) the probability of passengers, most who would be holding onto a seat back or other grab handle at the time being launched along the centrline of the train

c) the probability of any passengers staying airborne for more than a few metres​

Such approval would have been given elsewhere in Europe and the far-east years ago, well before the UK 'discovered' through open gangwayed rolling stock. I think that the idea of a clear path for even a single human body beyond what already exists has come from the ability to see that far. Just because you can see past the grab bars, accessible toilets etc., it doesn't mean that object as large as a human body would get very far. Imagining that a whole crowd of unfortunate passengers as projectives barreling through multiple cars is unrealistic and has no bearing on the absolute survivability of even a very rare type of collision.



If anybody is offended by my graphical description above then I apologise in advance, but such practical considerations are part of the safety world that is ultimately designed to protect us.

Perfectly summed up.