Waterloo & City - Bank Platforms

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Having been travelling on this line for 6 months now I still can't work out what decides which platform to use. Is there a formula to it, or is it on somebody's whim?

Mostly the right one seems to get used with occasionally dalliances into the left one. Is there a reason for this? Should infrastructure be used more evenly to spread the wear & tear on component parts?

 

[Peter Mugridge]

If both platforms are available then it is logical to send the next train into the right hand platform as that avoids the risk of delay from a conflicting movement. Off peak when there are fewer trains running this tends to result in that platform seeing the bulk of all movements.

In the peak with all the trains running both platforms will be used pretty much equally.

 

[rebmcr]

W&C signalling has automatic route setting, it's timetable-based with some limited intelligence for swapping.

 

[Mojo]

The scheduled platform is noted for all trains in the working timetable
http://content.tfl.gov.uk/wtt-7-waterloo-and-city-9-october-2017.pdf

However as stated towards the front of all LU WTTs: "The Signal Operator may vary the platform and siding working of trains in the best interests of the service."

In the peak with all the trains running both platforms will be used pretty much equally.

Even at the heart of the PM Peak with all five trains in service in the old timetable you only still needed to use one platform and this tended to be how things worked in reality too, with platform 7 used. Funnily enough a new timetable started this morning and the service now uses a mixture of both platforms.

 

[randompixel]

Thanks

 

[notverydeep]

Platform 7 has a shorter 'reoccupation time', the difference being significant enough for it to reduce the average round trip time, which is why it is used throughout the AM peak. In the PM peak this was adjusted during the closure at Tottenham Court Road Central line last year. At the most crowded times dwell times were lengthened with just platform 7 in use, such that the advantage of the shorter reoccupation time was lost. As this change generally mitigated platform crowding at Bank, it was left in place subsequently and has been incorporated into the Working Timetable (having been a 'Timetable Notice' previously). Note that the 'layovers' are not scheduled to overlap, with each arrival at Bank planned to depart before the next arrival, so both platforms should be clear as trains approach. Platform 8 is used at off peak times, when the duration of the round trip is less critical.