4DD under 1968, 1st edition, tops?

[Harlequinuk]

The Southern Region 4DD, was in service till 1971. By then the first version of TOPS was available and the second was being edited. So what would the 4DD TOPS number have been?

 

[Acathater]

I think you may have your dates confused.
from https://archivesit.org.uk/wp-content/uploads/2023/12/TOPS-for-History-of-the-Internet-January-2024-Draft-for-clearance.pdf#:~:text=The TOPS computer system was implemented by,British Rail network, working in real time.

The TOPS computer system was implemented by British Railways to monitor and control its freight traffic from August 1973 onwards. By Autumn 1975 TOPS kept track of every freight train, loco and wagon and their movements across the whole British Rail network, working in real time.

notice the original emphasis on freight

however google's AI claims:

The Southern Region 4DD electric multiple units were never allocated an official TOPS class number. The units were withdrawn from service in 1971, before the national rollout of the British Rail Total Operations Processing System (TOPS) in 1973-1975.
The units were originally numbered 4001 and 4002 in the pre-TOPS period under the British Rail numbering system. In the TOPS system, Southern Region DC electric multiple units were generally allocated class numbers in the 400-499 series, and it is sometimes speculated that the 4DD units might logically have been assigned Class 406 had they remained in service.

However as ever that's unreferenced as a claim and could be just another google hallucination

 

[Harlequinuk]

AE Robson BR’s CE(T&RS) in March 1968 , started with the first list of 2 or 3 digit classifications rolled out in October of 1968

 

[eastwestdivide]

If we’re speculating, SR class numbers ended in -5 for 4-car inner suburban units (405 SUBs, 415 EPBs, 445 PEPs and the 455s), and the few -6 classes were 2-car (416 EPBs, 446 the single 2-PEP).
As a double-deck though, perhaps the 4-DDs would have beenregarded differently.

That significance of the last number of the class applied quite widely, -0 for express with buffet (later -2), -1 for express, -3 for outer suburban 4-car, -4 for outer suburban 2-car.

 

[Ted633]

If we’re speculating, SR class numbers ended in -5 for 4-car inner suburban units (405 SUBs, 415 EPBs, 445 PEPs and the 455s), and the few -6 classes were 2-car (416 EPBs, 446 the single 2-PEP).
As a double-deck though, perhaps the 4-DDs would have beenregarded differently.

That significance of the last number of the class applied quite widely, -0 for express with buffet (later -2), -1 for express, -3 for outer suburban 4-car, -4 for outer suburban 2-car.

However, the earlier SR units were not numbered in such a way and seemed to be just given sequential numbers (probably as they didn’t have long left). The BIL, HAL, BEL, COR & SUB don’t fit the sequence that was applied to the later BR stock. Speculating, I think it would‘ve been class 406.

 

[eastwestdivide]

However, the earlier SR units were not numbered in such a way and seemed to be just given sequential numbers (probably as they didn’t have long left). The BIL, HAL, BEL, COR & SUB don’t fit the sequence that was applied to the later BR stock. Speculating, I think it would‘ve been class 406.

Fair point. Although the SUBs do fit the pattern at 405, were they in fact part of the 401-405 series of class numbers allocated to "old" stock?

 

[Ted633]

Fair point. Although the SUBs do fit the pattern at 405, were they in fact part of the 401-405 series of class numbers allocated to "old" stock?

They could be part of the pattern, but I’d say it’s just a happy coincidence.
If, for example, the class 404 didn’t exist (ie the CORs were retired before TOPS) and the SUBs were still numbered 405, then yes, I’d certainly say they were part of the pattern.

 

[Deepgreen]

Perhaps 408, on the same basis that Airbus called their double-decker the A380 - the 8 representing two decks...!

 

[frankmoh]

I think the 4DD could've been Class 407, as it was a special unit, however that system was done under the 1973 revision so maybe not?