"Current state" of berths

[Martin Thorpe]

Hi all,

Xiaocheng’s request for TD messages the other day got me thinking about this again. The C class messages give us changes of state in berths, but is there any source of what’s currently in any given berth, or even better, all berths for a given area? Otherwise you only know about any given berth once you’ve received an appropriate interpose, cancel or step and you have to integrate all of those updates to get the current state.

For frequently updated berths it’s not too much of a problem, but even with data going back to the beginning of May I am still seeing berths for the first time (BU 0151 was a new one to my data on Thursday afternoon, for instance.)

This doesn’t matter anywhere near as much for S class messages of course since you have the SG and SH messages to refresh state at reasonably frequent intervals.

Thanks,

Martin

[Peter Hicks]

Hi Martin

There isn't any mechanism to get the current content of a berth through the Open Data platform.  The only way you can do it is to set something up to record the stream of messages and keep a state table up-to-date.  From there, you can easily get the current content of a berth, or multiple berths, or all berths reported via a particular SMART-connected train describer, etc.

The SG and SH messages are actually generated in response to a 'base scan request' by a system at Network Rail which sends out the request every few hours.  In theory, the same could be done for berths - the command exists and is defined in the protocol - but there are going to be valid reasons why it wasn't done - e.g. risk of overloading smaller-capacity links, processing overhead on the train describer, etc.

Peter Hicks

Director

OpenTrainTimes Ltd.

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[Martin Thorpe]

Thanks for the quick reply Peter! All makes sense :)

Best wishes,

Martin