Trains with duplicate headcodes at the same location

[greatkingrat]

I noticed today there were two trains with identical headcodes leaving Clapham Junction within minutes of each other.

2L33 1207 Waterloo - Basingstoke / Alton (dep Clapham J 14 late at 1230)
2L33 1229 Clapham Junction - Stratford (dep Clapham J 6 late at 1235)

These seem to be booked WTT paths, not temporary alterations, so I am surprised the clash hasn't been picked up yet and one of the trains changed. Is there any procedure to automatically check the timetable for potential headcode clashes, or is just reliant on them being noticed manually?

 

[whoosh]

Normally you should plan for there to be a gap of six hours between trains of the same headcode in the same signalling area.
The two different routes these trains run, might mean they are dealt with by different signalboxes or signalling panels.

Actually, each one will be individual as there two letters afterwards in the train planning system, which which will mean there won't be an absolutely identical train more than once a day anywhere in the country.

 

[TheEdge]

Isn't that area quite weirdly signalled? So even though they are physically in the same location different sides and lines around Clapham are controlled by different boxes so no actual clash. Much like how London Victoria has different boxes controlling the Southern and Southeastern sides.

 

[jamesst]

Isn't that area quite weirdly signalled? So even though they are physically in the same location different sides and lines around Clapham are controlled by different boxes so no actual clash. Much like how London Victoria has different boxes controlling the Southern and Southeastern sides.

Never realised that,how many boxes cover Clapham?

 

[swt_passenger]

Never realised that,how many boxes cover Clapham?

The major split is between the Southern (Victoria area signalling) and Southwestern (Wimbledon area signalling) ‘routes’. Think of an imaginary line dividing the two networks down the middle, between SWR down main slow and SN up main fast. There are no direct running connections. But each signalling centre has many panels, so the risk of a clash of train IDs is minimal. The SW main side and Windsor side are fairly well separated operationally as well.

The actual LO platforms and their approaches can be operated completely separately from the SWR Windsor side on a normal day to day basis, but AFAICS from online sources the platforms themselves are still under Wimbledon control, with a signalling boundary with Victoria very nearby on the Latchmere lines.

 

[TheEdge]

Now I'm wondering how the GSMR around there works. Are drivers guaranteed to get the "right" box when they use REC, urgent or point to point calls or is there some sort of managed overlap?

 

[carriageline]

Now I'm wondering how the GSMR around there works. Are drivers guaranteed to get the "right" box when they use REC, urgent or point to point calls or is there some sort of managed overlap?

GSMR works off train describer berths. So, 1H11 is at signal VC117 (fictional!) and on the signallers display, it will be in the train describer berth for VC117. So the GSMR sees 1H11 in berth for VC117, so will divert calls to the signaller controlling VC117

All being well, if the drivers have set up correctly, 90% of the time it will work correctly. You get issues when the GSMR has a brain fart, or if a driver hasn’t set up, or hasn’t set up correctly.

In that situation, the GSMR will divert the call to whatever signaller is the “master” for the cell area(preprogrammed at commissioning)

 

[bb21]

Now I'm wondering how the GSMR around there works. Are drivers guaranteed to get the "right" box when they use REC, urgent or point to point calls or is there some sort of managed overlap?

In short, no they aren't.

Clapham are already seeing changes due to complaints so two weekday morning services already had changes imposed recently, 2L13 into 2L97 and 2L15 into 2L99. It is also far from a rare occurrence that some trains on the SW side being picked up at Balham and the system then threw a hissy fit.

 

[jon0844]

GTR have mistakenly cancelled the wrong Moorgate train on Trust as headcodes are reused in a single day.

 

[JN114]

Now I'm wondering how the GSMR around there works. Are drivers guaranteed to get the "right" box when they use REC, urgent or point to point calls or is there some sort of managed overlap?

Although a REC call would stop all lines anyway as they’re adjacent cells.

 

[GW43125]

Isn't that area quite weirdly signalled? So even though they are physically in the same location different sides and lines around Clapham are controlled by different boxes so no actual clash. Much like how London Victoria has different boxes controlling the Southern and Southeastern sides.

The two Victorias are on the same operating floor, but are operationally separate.
Waterloo platforms 1-14 and the main lines to Clapham are Wimbledon Panel 1
Waterloo platforms 15-24 and the Windsor lines (as well as Clapham platforms 1&2) out to Putney are Wimbledon Panel 2

 

[DarloRich]

how many combinations of a 4 digit alpha numeric code are there? How many trains are run everyday. Could it just be a coincidence?

 

[TheEdge]

how many combinations of a 4 digit alpha numeric code are there? How many trains are run everyday. Could it just be a coincidence?

A lot more than there are trains. The only reason we get clashes is because we use patterns and rules. If any train could be any permutation of xYxx then they'd never clash. But then we limit passenger services to only 2/10ths of what is available, then chuck in the letter rules and clashes become possible

 

[CMS]

Deleted

 

[greatkingrat]

Although Eurostar actually use 90** and 91**, it's just that some systems display it as 9O or 9I because they aren't set up to deal with all numeric codes.

 

[_toommm_]

how many combinations of a 4 digit alpha numeric code are there? How many trains are run everyday. Could it just be a coincidence?

Assuming I'm calculating this correctly, its 10x26x10x10=26,000 alphanumeric combinations. As for how many run everyday varies, as some freights don't always run, and there's always VSTP headcodes coming into force. Then there's bus replacements which are always 0B00 regardless of where or when operated.

 

[87015]

Assuming I'm calculating this correctly, its 10x26x10x10=26,000 alphanumeric combinations. As for how many run everyday varies, as some freights don't always run, and there's always VSTP headcodes coming into force. Then there's bus replacements which are always 0B00 regardless of where or when operated.

Buses are never 0B00 in planning context, it’s just a downstream mask. They have six digit “ID” in exactly the same way as any train in reality, just starts with a B.

 

[IanXC]

Although Eurostar actually use 90** and 91**, it's just that some systems display it as 9O or 9I because they aren't set up to deal with all numeric codes.

Operationally, on HS1 metals, I'm fairly certain the services operate as 9Oxx and 9Ixx - it being a convenient situation that 90xx and 9Ixx coincide.

 

[JN114]

Operationally, on HS1 metals, I'm fairly certain the services operate as 9Oxx and 9Ixx - it being a convenient situation that 90xx and 9Ixx coincide.

Indeed - as I understand it 90xx/91xx were chosen on the continent because they were the best match that could be easily translated onto the British system; not the other way around as previously inferred by greatkingrat.

But even those ranges aren’t reserved solely for International services.