Passcom question

[waynemorrell]

Hi,

I noticed on the 313’s (Southern) they have covered up the communication cords with a piece of plastic one must peel off before pulling the actual cord, presumably to prevent misuse, but is this a good idea? All adds extra time in an emergency.

I’ve only seen this on Southern trains, the Merseyrail 508’s (which I believe are similar to 313’s) use a intercom system as used on more modern stock but I assume they had the cord before the refurb?

On the 318 I was on yesterday it’s still the cord and no cover.

BTW how do these cords work? On the old CIG VEP stock ect it was a butterfly valve on the end of the carriage connected to the brake pipe, no sign of anything external on 31x though.

And do these cords still apply the brakes ?

Just curious that’s all.

Thanks.

 

[tsr]

Various trains have covered passcoms - including other routes around London such as Thameslink (the Class 700s actually have a very sturdy plastic cover which you basically have to smash your way through), and also on the Tube. Covered alarms prevent people pushing them accidentally, plus it tends to be the cover that attracts the attention of small children who climb around the train in moments of boredom, rather than the big scary red button itself.

However, red buttons are the more modern equivalent, which typically sound an alarm in the driving cab (plus other cabs on some stock, notably Turbostars), generally activate the Bodyside Indicator Lights on the relevant coach, display an alert message on the Train Management System where provided, and connect the driver to the call being made. Should the driver not respond to the alarm by means of an override switch or pedal, the brakes would still apply. With or without the override (which can be used to get the train to a more suitable stopping point), if there is a call-for-aid voice intercom, the driver may be able to talk to the passenger, on the assumption they are still in situ, conscious and alert, and it's not a false alarm.

On less modern trains, like older Southern stock, a big red plastic tab over the top of the passcom generally covers a red alarm handle which serves the now rather dated purpose of directly stopping the train by causing a brake application. This is great if you are a conductor and notice a problem during dispatch, but less so if you are a passenger and you're feeling ill. You won't necessarily see the mechanism, as this is often now hidden underneath an interior panel, near the alarm. Override switches, isolation systems and suchlike are likely to be elsewhere.

 

[TheEdge]

The middle age style of passcom that stops the train but doesn't have an old fashioned butterfly valve works by breaking the electronic brake continuity wire which triggers an emergency brake application

 

[Alan2603]

Did I read somewhere that if multiple passcoms are activated, then the driver has to clear each one individually. Only once they are all 'cleared' can the driver then make a PA announcement to let passengers know he is aware of the situation? This seems strange as I thought the PA would be able to overide the passcoms in the case of multple activations so passengers know the situation is being handled and no further passcoms are required.

Also on such as the London Underground, are the brakes automatically applied immediately the alarm is activated?. Wouldn't it be better to let the train get to the next station stop where the pax can be evacuated quicker or help sought from platform staff etc?

 

[Mugby]

I believe the old style butterfly valves could be re-set simply by leaning out of a carriage door droplight and reaching up to it.

Something which is no longer possible on modern stock of course.

 

[BestWestern]

Also on such as the London Underground, are the brakes automatically applied immediately the alarm is activated?. Wouldn't it be better to let the train get to the next station stop where the pax can be evacuated quicker or help sought from platform staff etc?

On the Underground the alarm signage states that if the train is still partially in a station, it will stop. If not, it will continue to the next station. What the mechanism is for making that work I've no idea.

 

[Lrd]

On the Underground the alarm signage states that if the train is still partially in a station, it will stop. If not, it will continue to the next station. What the mechanism is for making that work I've no idea.

There's a timer that counts up every time a train leaves a station. But it's not accurate so the train can stop when no where near a station if you have a fast enough departure.

On older stocks (Bakerloo for example) there is no timer and it will apply the brakes no matter where you are, it's up to the driver to stop or override and carry on.

 

[BestWestern]

There's a timer that counts up every time a train leaves a station. But it's not accurate so the train can stop when no where near a station if you have a fast enough departure.

On older stocks (Bakerloo for example) there is no timer and it will apply the brakes no matter where you are, it's up to the driver to stop or override and carry on.

That's very interesting, thanks!

 

[Mag_seven]

There's a timer that counts up every time a train leaves a station. But it's not accurate so the train can stop when no where near a station if you have a fast enough departure.

Is that what the 1, 2, 3, 4 etc signs are for that you see on the tunnel wall when you depart or is that for something else?

 

[Dhassell]

Is that what the 1, 2, 3, 4 etc signs are for that you see on the tunnel wall when you depart or is that for something else?

Yep. Tells the driver how many coaches outside the station he/she is.

 

[Mag_seven]

Yep. Tells the driver how many coaches outside the station he is.

Thanks for that.

 

[tsr]

Did I read somewhere that if multiple passcoms are activated, then the driver has to clear each one individually. Only once they are all 'cleared' can the driver then make a PA announcement to let passengers know he is aware of the situation? This seems strange as I thought the PA would be able to overide the passcoms in the case of multple activations so passengers know the situation is being handled and no further passcoms are required.

Can’t say that I’ve ever heard of any stock where that happens, but I could be wrong. On older stock, the passcom being linked to the brakes would also usually mean it was part of an analogue system which would have nothing to do with PA audio transmission.

Passcoms linked to electronic systems on some modern trains do have their quirks. They may also display errors on the train management system which need to be cleared or acknowledged before the train can proceed as normal. I have had one or two trains with faulty wiring where the passcom voice transmission has been passed over the PA (which did not amuse me when a rather important announcement was broken into by somebody who got stuck in the loo...). But normally the driver’s radio and announcements take priority over other voice transmissions.

 

[GW43125]

On the Underground the alarm signage states that if the train is still partially in a station, it will stop. If not, it will continue to the next station. What the mechanism is for making that work I've no idea.

That's on ATO lines too, presumably the ATO computer knows where it is.

 

[Dhassell]

That's on ATO lines too, presumably the ATO computer knows where it is.

I would presume so. I have had the passcom pulled on a Victoria Line train. We must have still had at least 1 carriage on the platform when we stopped. So clearly It did know where we were.

 

[GW43125]

I would presume so. I have had the passcom pulled on a Victoria Line train. We must have still had at least 1 carriage on the platform when we stopped. So clearly It did know where we were.

Some use a timer as mentioned above, so it could be either was what i was alluding to