Trivia - Duplicate Headcodes At Redhill

[Deepgreen]

A semi-trivia post. This morning there were Hastings to London Bridge diversions via Redhill. At the same time a Hastings to Eastleigh railtour (the 'Mick Tester'), using 'Hastings' DMU 1001, ran from Hastings via Redhill. It had headcode 1Z17. While it was standing at its reversal at Redhill, a London Bridge to Hastings working approached, also with headcode 1Z17. The two didn't actually meet but it was close. Purely out of idle curiosity; how often do two trains with the same headcode come this close to meeting? A few minutes' delay would have seen two 1Z17s in the station together.

Incidentally, as the North Downs line runs across our lane at Gomshall, I popped down to see it (at Burrows Lane AHB) and was treated to a whistle from the driver (as opposed to two-tones). The AHB is to become a full barrier crossing next month.

 

[30907]

The special didn't show up on a RTT search but (of course) you are right.

Very unusual with the trains being on the same route (and in opposite directions!) - I wonder if different offices dealt with the engineering diversions and the special?

 

[Class15]

A few I can think of:

Stratford - any slower trains to Clacton would share 2Nxx headcodes with North London line services.
Clapham Junction - Southern services towards Wembley Central share 2Mxx headcodes with some SWML commuter services (maybe Chessington but not sure)
During a Boxing Day LO timetable IIRC, two 2N40’s crossed at West Hampstead!
Until the December TT change NLL services at Stratford towards Primrose Hill or the City Loop lines would share 2Mxx headcodes with Meridian Water trains. Now the latter have 9Mxx…

 

[Eloise]

The special didn't show up on a RTT search but (of course) you are right.

Very unusual with the trains being on the same route (and in opposite directions!) - I wonder if different offices dealt with the engineering diversions and the special?

Same office different teams. Shouldn't happen really but dealing with tens of thousands of headcodes duplicates slip through. Once spotted they will be fixed, especially in the WTT. It's why you see oddball headcodes from time to time, usually fixing a duplicate that's been found.

 

[Deepgreen]

The special didn't show up on a RTT search but (of course) you are right.

Very unusual with the trains being on the same route (and in opposite directions!) - I wonder if different offices dealt with the engineering diversions and the special?

Briefly in the same direction as 1001 headed to Reigate. Of course the risk of it causing any issue is miniscule - just an interesting anomaly. When 1001 returns to Redhill at 1649-1656 as 1Z18, it should pass the appropriately-numbered 1Z66 on diversion!

 

[Eloise]

Whilst the risk is small it is still a risk. If spotted and running again it is taken very seriously and it would be changed.

 

[Deepgreen]

Whilst the risk is small it is still a risk. If spotted and running again it is taken very seriously and it would be changed.

Interesting. Railtours always use 1Zxx headcodes so I imagine it would not be too hard to design and run an algorithm to check for clashes, or perhaps one already exists and needs a tweak. This particular one was noteworthy to me as it involved two trains on the same basic route, i.e. from Hastings to Redhill. It was only when I happened to check 'Traksy' for the tour's position that I noticed the Hastings diversions. For anyone interested this was my short video:

 

[Eloise]

I'm no expert in the technical side but we have tools to check. It is complex though. The fact you can have two 1Z17 for example isn't an issue if they don't appear in the same signal box area within (generally) 6-12 hours*. So you can have two 1Z17 geographically very close together but neither actually lands on the same panel and that's fine. You can have two 1Z17 50 miles apart but they appear on the same panel is more serious. Add in GSMR areas and that's a further layer to factor in.

* I know, as ever there are exceptions.

 

[Deepgreen]

I'm no expert in the technical side but we have tools to check. It is complex though. The fact you can have two 1Z17 for example isn't an issue if they don't appear in the same signal box area within (generally) 6-12 hours*. So you can have two 1Z17 geographically very close together but neither actually lands on the same panel and that's fine. You can have two 1Z17 50 miles apart but they appear on the same panel is more serious. Add in GSMR areas and that's a further layer to factor in.

* I know, as ever there are exceptions.

Thanks. So yesterday was a relatively serious breach, then. Perhaps it's lucky 1001 wasn't sent back down to Hastings, while a 375/377 attempted the railtour!

 

[Eloise]

Not really a serious breach. Too strong that I would say. It happens and looked into and you take the learning. If spotted or had caused an issue Control can (and have in the past) intervene there and then. Drivers would stop and challenge any wrong routing.

 

[Deepgreen]

Not really a serious breach. Too strong that I would say. It happens and looked into and you take the learning. If spotted or had caused an issue Control can (and have in the past) intervene there and then. Drivers would stop and challenge any wrong routing.

Indeed - I did say "relatively" (based on your broad categories) and the rest was light-hearted.