Selective door operation - standardisation and improvements?

[Bletchleyite]

On recent discussions about SDO, it seems to me that there are a load of different systems, some of which are better than others. For example, GPS based systems don't prevent wrong-side release or stop-short.

So should it be standardised?

It occurred to me that a system based on unpowered balises, placed at the start and end of platforms on the side of the platform, which would enable a given vehicle's doors when they pass it, and disable them again when they pass another one on the same side, would be a fairly simple and not that expensive in the scheme of things. Perhaps it would also need a failsafe, such as to disable all doors when power has been taken for a certain amount of time, just in case one was missing or failed. The vehicle would need an aerial on each bogie to pick them up.

Can anyone see a major flaw in that idea? It strikes me that it has fewer gaps than the GPS based systems.

 

[zwk500]

On recent discussions about SDO, it seems to me that there are a load of different systems, some of which are better than others. For example, GPS based systems don't prevent wrong-side release or stop-short.

So should it be standardised?

It occurred to me that a system based on unpowered balises, placed at the start and end of platforms on the side of the platform, which would enable a given vehicle's doors when they pass it, and disable them again when they pass another one on the same side, would be a fairly simple and not that expensive in the scheme of things. Perhaps it would also need a failsafe, such as to disable all doors when power has been taken for a certain amount of time, just in case one was missing or failed. The vehicle would need an aerial on each bogie to pick them up.

Can anyone see a major flaw in that idea? It strikes me that it has fewer gaps than the GPS based systems.

I'd be all for it, although it depends if there's other equipment in the 4' that would interfere like ATP/TPWS/AWS, or newer ETCS equipment when it comes. There's also the question about how close do you put the balise to make sure that, say, the last coach of an 8-car train doesn't open on a 7-car platform? The last enabled door will be pretty close to the first disabled door?

 

[py_megapixel]

I guess the main disadvantage is that if you have it entirely based on activating and deactivating doors like that, then if you want to update the system you have to physically go and move or replace the balise rather than just tweaking something in software, which makes the system more expensive over time. There would also still need to be a means for the train to 'know' which doors it was going to open because locked-out doors need to be announced on the PIS ahead-of-time.

According to some old training videos I found on YouTube (not really an authoritative source, I know)... the 458s on SWR already have this kind of system, but there is no deactivation balise at the end of the platform; it just relies on resetting once a certain speed is reached. Can anyone comment on how reliable the SDO system on the 458s is?

There's also the fact that the SWR Aventras will, IIRC, be capable of releasing the doors themselves as soon as they arrive at a station. Presumably that will have to use something more reliable than GPS.

 

[Bletchleyite]

According to some old training videos I found on YouTube (not really an authoritative source, I know)... the 458s on SWR already have this kind of system, but there is no deactivation balise at the end of the platform; it just relies on resetting once a certain speed is reached. Can anyone comment on how reliable the SDO system on the 458s is?

I suppose that would also work - the main benefit of a deactivation balise is that it would be able to deal with situations where you might want to open doors in the middle rather than always from the front. There aren't many such situations, that said. You'd also have a second balise on any bi-directional platforms anyway.

 

[py_megapixel]

I suppose that would also work - the main benefit of a deactivation balise is that it would be able to deal with situations where you might want to open doors in the middle rather than always from the front. There aren't many such situations, that said. You'd also have a second balise on any bi-directional platforms anyway.

I wonder if the flexibility to open doors anywhere on the train could help with crowd control at busy times. Open the rear 5 cars of an 8-car formation at one station, then the front 5 cars at the next and so on. It could help to spread passengers throughout the train.
The disadvantage is that it could cause confusion for passengers making short journeys as they'd have to walk through the train.

There is another way that this could be used - if you put the wheelchair accessible areas at the ends of units and then couple them so that they back on to each other, then if you can open doors in the middle you can reduce the possibility of a wheelchair user becoming "trapped" by the SDO because they can't get through the train (as all or most wheelchair spaces will be on the platform at every station).

 

[Energy]

So should it be standardised?

Yes, having multiple systems is a bit of a pain. Also: XKCD 927.

 

[etr221]

My thought on SDO was that the way to have gone was to have put a wire (or two) as some sort of induction loop along the edge of the platform (half way up), and have something on the train (each carriage?) that could detect it, to say 'there is a platform alongside, doors can open'... (with perhaps some thing to switch it off whan platform was closed, if you want a bit more sophistication)

 

[Nym]

The Sella Controls ASDO system seems to have become ubiquitous but is not "standard"
A "standard" system would need to be based on ETCS Baleises long term, but that's well, very expensive.

 

[43096]

According to some old training videos I found on YouTube (not really an authoritative source, I know)... the 458s on SWR already have this kind of system, but there is no deactivation balise at the end of the platform; it just relies on resetting once a certain speed is reached. Can anyone comment on how reliable the SDO system on the 458s is?

When first implemented it was rather unreliable, with numerous "fail to open" events on random vehicles that were at the platform and should have opened, often with passengers over carried as a result. It's much more reliable now and it's some time since I've had a fail to open when travelling on them - but then I haven't used them as much over the last 13 months.