Incorrectly docked train

[class411]

I was waiting for a train a Shepherd's Bush Market yesterday. Indicator said Hammersmith 2 mins. The train came pouring into the station at a rate of knots, and stopped about two foot forward of its normal stopping point (the front doors were just clear to the correct side of the 'do not pass this point' swing gates at the end of the platform).

Nothing happens for about twenty seconds, then there is a clunking sound from the cab and the doors in the carriages other than the front open.

A few questions:

1) Was the pause caused by the driver manually setting the selective door opening mechanism?
2) As the train was in a position whereby all the doors could have been safely used, why did he need to use the selective feature?
3) If the system forced him to use it, does that mean it has a 'nearly right' range that allows doors in rear carriages to be opened?
4) (Probably a stupid question to those in the know but ...) Is it not possible to reverse a train even a couple of feet without prohibitively (in this particular circumstance) time consuming protocols being followed?

[Colin]

Feb 20, 2019 9:33:01 GMT class411 said:

A few questions:

1) Was the pause caused by the driver manually setting the selective door opening mechanism?
2) As the train was in a position whereby all the doors could have been safely used, why did he need to use the selective feature?
3) If the system forced him to use it, does that mean it has a 'nearly right' range that allows doors in rear carriages to be opened?
4) (Probably a stupid question to those in the know but ...) Is it not possible to reverse a train even a couple of feet without prohibitively (in this particular circumstance) time consuming protocols being followed?

1) In simple terms, yes.
2) Because they haven't lined up correctly with the correct side door enable equipment, they are forced to use the emergency override and that automatically inhibits the leading car's doors.
3) Yes, its what is known as overshoot mode. If the leading car passes through the correct side door enable equipment at a low enough speed that the train is confident it is in a platform, overshoot mode kicks in and allows the rear car's doors to open.
4) Not without setting up the setting back procedure which invloves the line controller and service manager - it would take too long compared to just using the emergency override. A driver moving a train backwards without authority, "even its only a foot", will be looking at starting a new career with a new employer.

[aslefshrugged]

Just to be pedantic a train is "berthed" in a platform not "docked".

[class411]

Feb 20, 2019 9:43:26 GMT Colin said:

Feb 20, 2019 9:33:01 GMT class411 said:

A few questions:

1) Was the pause caused by the driver manually setting the selective door opening mechanism?
2) As the train was in a position whereby all the doors could have been safely used, why did he need to use the selective feature?
3) If the system forced him to use it, does that mean it has a 'nearly right' range that allows doors in rear carriages to be opened?
4) (Probably a stupid question to those in the know but ...) Is it not possible to reverse a train even a couple of feet without prohibitively (in this particular circumstance) time consuming protocols being followed?

1) In simple terms, yes.
2) Because they haven't lined up correctly with the correct side door enable equipment, they are forced to use the emergency override and that automatically inhibits the leading car's doors.
3) Yes, its what is known as overshoot mode. If the leading car passes through the correct side door enable equipment at a low enough speed that the train is confident it is in a platform, overshoot mode kicks in and allows the rear car's doors to open.
4) Not without setting up the setting back procedure which invloves the line controller and service manager - it would take too long compared to just using the emergency override. A driver moving a train backwards without authority, "even its only a foot", will be looking at starting a new career with a new employer.

Thanks for such a clear and comprehensive answer.

Feb 20, 2019 10:06:40 GMT aslefshrugged said:

Just to be pedantic a train is "berthed" in a platform not "docked".

I thought it didn't seem quite right as I typed it.

[brigham]

The confusion arises because a bay platform for goods is termed a 'dock'.

[t697]

Feb 20, 2019 10:06:40 GMT aslefshrugged said:

Just to be pedantic a train is "berthed" in a platform not "docked".

The SSR ATC engineers talk about 'docked' to mean the ATC is satisfied the train has stopped within tolerance to open the doors and I think it's used on the Jubilee/Northern system too. So I guess we may need to get used to the term sometimes!

And in SSR ATC the 'overshoot mode' is gone. In the overshoot situation described in the first post, both the front and rear cars' doors would stay shut once we have ATC.

[punkman]

Feb 20, 2019 18:36:09 GMT t697 said:

Feb 20, 2019 10:06:40 GMT aslefshrugged said:

Just to be pedantic a train is "berthed" in a platform not "docked".

The SSR ATC engineers talk about 'docked' to mean the ATC is satisfied the train has stopped within tolerance to open the doors and I think it's used on the Jubilee/Northern system too. So I guess we may need to get used to the term sometimes!

And in SSR ATC the 'overshoot mode' is gone. In the overshoot situation described in the first post, both the front and rear cars' doors would stay shut once we have ATC.

I was present when some of the TBTC testing was done for the Jubilee line, and some of the engineers referred to "docking;" in fact I think there are "docking loops" in the platform to ensure accurate stops on TBTC equipped trains.

[Deleted]

On SSL with CBTC it will be accurate stopping tags instead of the physical loop

[roythebus]

Will that system ever work?

[Deleted]

Find out in 3 weeks when the next planned start up will be