Stratford describer

As the train was departing so maybe you saw it changing to the next trains - rather than the one that was leaving the station?

Whilst I'm not particularly familiar with the Central line's Westcode signalling system, the basic principle is likely similar.....

Some basic signalling principles to note:

• Platform describer boards are generally driven by the signalling system
• The track is usually divided into track circuits with a signal placed at the start of each one
• In very basic terms, the signalling system can "see" a given train moving along the line as it operates the track circuits

Given the above information, hopefully you'll be able to understand that as a train departs the platform it moves onto the next track circuit. The signalling system can then work out that the train is departing the platform and will change the display on the platform indicator to show the details of the next train to arrive at the platform. This happens before the departing train has fully left the platform which creates what you probably saw - the platform display changing its information as the train you observed departed.

Indeed - the D stock braking system was Westcode - obviously mixed the two up in my mind!

The Westcode term was certainly mentioned as a catch-all term but equally we were very much trained in the how the braking system worked. I’m getting rusty now but can recall the seven step relay and how we only used three of the steps on D stock, for example.

Anyway, we’ve drifted off topic somewhat….

Is it perhaps that, unusually, a Woodford bay terminator was the train whose tail I saw, and the T/op had merely made a mistake in setting the rear DMI?
Or is there a lunchtime terminator now scheduled? (I have lost my link to the current WTT in an extended absence from the Central Line.)

I might be able to take an educated guess.

There are predicted ONA's (train operator not available for specific duties) for each day - with these a plan can be put in place to stable the train early awaiting a train operator to bring it back into service.

There are also late notice ONA's, eg Train operator books off sick before their duty, is late to work due to service disruption on other lines or bad traffic etc.

In the late notice scenario, the relevent Trains Manager will contact the Controller to inform them that train XXX has no relieving driver at its booked point.

Sometimes this can happen as late as when the train sitting in the relevent platform waiting for the new driver.

If there is no relief available for the current driver, then they have to take the train to the nearest depot or sidings and stable the train.

In the case of Leytonstone, a train crew depot and relief point, the nearest sidings is Woodford, any train going into Woodford sidings will show as South Woodford on the train describer dot matrix as it has to detrain at the previous station before going into the sidings.

A train going through Stratford Eastbound is about the right time for the controller to find out about a late notice ONA, If that was the case, the signaller would be informed to divert the train to Woodford sidings and the train describer and dot matrix would change to say South Woodford, the Train Operator will then be informed about the situation.

Maybe in your case, the train operator was still in the process of being informed of the situation and you just happened to catch the discrepancy with the dot matrix and the train as it departed.