Train door control systems

[eoff]

I would like to understand how trains can disable particular doors.

A year or two ago (not sure of timing) new trains arrived on the North Berwick line and on that line some platforms are shorter than the train.
For many months the following situation would arrise.

A train would arrive (empty) at platform 8 in Edinburgh Waverley, from the East to form a service departing East to North Berwick.
If you were lucky the train doors would all open, you could board the train and it would depart a few minutes later.
However on many occasions the doors on the (now) front carriage would be locked (the button illuminates red) and as far as I could tell this was something to do with the train being programmed for the route and something had to be reset or had not yet been set for the outgoing journey.
Note that platform 8 is divided into 8W and 8E, these are too small for the train in question, and in fact the train did not always stop at the expected arrival 'platform'.

Can someone explain what was going on? Platform staff never had a clue and always claimed the doors were faulty which was clearly not true because usuallly they opened within 1-4 minutes of arrival, sometimes not before the train departed and you had to enter in the second carriage and walk through.

I suppose this is better than when the 125s ran on the line and we were trusted not to open the door and get out if there was no adjacent platform.

 

[TheEdge]

Off the top of my head there are three basic systems (excluding physically locking a door out of use).

First is door deselecting. This is manually done by the member of staff releasing the doors at each station. The only example I've seen of this is on Class 170s I used to work where a button in the cab would deselect only the doors in that coach, and it reset each time the train moved.

The other two are both different versions of (Automatic) Selective Door Opening (SDO/ASDO). One system, which sounds like the one you are coming across is based on the train knowing which platforms are too short and which doors need to remain locked, assumes the driver has stopped correctly and then only releases the doors it expects to be on the platform. In your example if the system has the wrong location set (i.e the driver has full use of all of 8 but the system thinks its only got use 8W) it'll lock doors that should be open.

The other version of SDO/ASDO is based on GPS bubbles and transmitters in the track. The train uses the GPS to detect at what station it is, then looks for the transmitters on the tracks, works out which doors to open based on where it is and releases those doors.

 

[hwl]

I would like to understand how trains can disable particular doors.

A year or two ago (not sure of timing) new trains arrived on the North Berwick line and on that line some platforms are shorter than the train.
For many months the following situation would arrise.

A train would arrive (empty) at platform 8 in Edinburgh Waverley, from the East to form a service departing East to North Berwick.
If you were lucky the train doors would all open, you could board the train and it would depart a few minutes later.
However on many occasions the doors on the front carriage would be locked (the button illuminates red) and as far as I could tell this was something to do with the train being programmed for the route and something had to be reset or had not yet been set for the outgoing journey.
Note that platform 8 is divided into 8W and 8E, these are too small for the train in question, and in fact the train did not always stop at the expected arrival 'platform'.

Can someone explain what was going on? Platform staff never had a clue and always claimed the doors were faulty which was clearly not true because usuallly they opened within 1-4 minutes of arrival, sometimes not before the train departed and you had to enter in the second carriage and walk through.

I suppose this is better than when the 125s ran on the line and we were trusted not to open the door and get out if there was no adjacent platform.

Have a search for Automatic Selective Door Operation or ASDO, this has all been covered many times before.

The simple (cheap) implementations use GPS hence no GPS signal it defaults to the shortest platform length at that station. (unlikely in this case as it should be rear doors lost)
The better more modern implementation use balises fitted to the tracks to provide platform specific and position specific (hence where on P8 matters) door opening so that only doors in platform open. 8E and 8W are possibly treated as seperate platform by the system so if the train bridges the 2 platforms some doors won't open. The systems programming was designed for stations like Waverley so will have needed some head scratching to sort.
Some of the more modern implementations also provide correct side door enabling (CSDE) so that the doors only open on the right (correct) side.

 

[philthetube]

GWR HST's had a system where the guard could operate a switch so that only the doors in front of that position were released.