Class 7xx - seemingly random numbering?

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nw1

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One thing that's striking me about the class 7xx, which was presumably introduced recently because they were running out of spare 3xx classes to use, is the rather bizarre numbering scheme.

First one was, IIRC, the 700 - fair enough. However since then the numbering seems to have been almost haphazard and random. Logic might dictate that they would either be numbered in chronological order (so that the second class to be introduced would be the 701, then the 702, then the 703 etc - similar to how the AC 3xxs are numbered, at least up to the 325) or some sort of systematic numbering as was done on the southern (so that 700-09 are manufacturer A, 710-19 manufacturer B, and so on).

Instead the numbering seems almost like the output of a random number generator. Maybe there are patterns, but they are not obvious (why did the 707 come before the 701, for instance?) It also begs the question, given that the 7xx has ended up with the same haphazard patterns as the later 3xx (it was logical up to and including the class 325, then went a bit strange) any new units are going to have to use the unclaimed numbers. If that is the case, there are plenty of unclaimed numbers in the 3xx range (starting, I think, with 326-329) so why didn't they just use up all the 3xx before moving onto the 7xx?
 
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dm1

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As I understand it, the TOPS classification system is now more or less a complete free-for-all and the manufacturers can request any available number they like (at least the last two digits) that they think will work well for marketing purposes.
 

hwl

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Some TOCs also try to have uniquefirst digit of last 4 digits for each stock type e.g. SWR wanted 1xxx for their new stock hence 701, 711, 721 etc as possibilities
 

norbitonflyer

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I did read somewhere that the gaps in the 3xx series, and the new 6xx,7xx and 8xx blocks, were necessary to avoid unit numbers duplicating individual vehicle numbers (BR wagons always had six-digit numbers, although coaching stock was until recently five digits).

But then we see that individual vehicles of:
class 331 have been allocated numbers in the 4651xx and 4660xx series,
class 385 in the 4440xx series,
class 701 in the 4840xx series,
class 717 in the 4560xx series,
class 720 in the 4501xx and 4505xx series,
class 745 in the 3131xx, 3320xx

All of which duplicate numbers already allocated to complete units

Actually the first class to break the linear sequence of 3xx class numbers was class 370, in about 1980 (around the same time as Class 315) but if you allow high speed units their own 37x sequence (also used by Eurostar), then class 365 was the first anomaly. That number was presumably chosen to align with the other members of the Networker family, classes 465 (which fit logically into the Southern's numbering scheme) and class 165 (which partially did so as all previous blocks up to 15x had been used).

By my calculations, thirty-seven "straight" electric classes have been introduced or had numbers allocated since class 365, disregarding high speed units (classes 390, 395, 397 and the 8xx series), the class 399 tram trains, and any numbered in the 4xx series. This would have taken us to class 362.

Bi modes seem to be numbered in a block starting at 750 (although Merseyrails's 777s are in there too). Although they, like electro-diesel locos, are classified in an "electric" series, arguably they should be numbered like other "go-anywhere" units (2xx or 6xx), leaving the 3xx, 4xx, 5xx and 7xx blocks to identify units that cannot go "off the juice".
 

southern442

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Essentially there are some sub-patterns but no overarching rule at all. Any time you find a suspected rule for numbering, you can always find a counter-example.

Aren't there are a few 'hidden' classes, where individual units or prototypes have been grouped together? I seem to recall a class for railbuses, something like 136, and maybe another one for Wickham trolleys, but again I am not sure. Either way these only explain one or two minor gaps.
 

swt_passenger

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…Bi modes seem to be numbered in a block starting at 750 (although Merseyrails's 777s are in there too). Although they, like electro-diesel locos, are classified in an "electric" series, arguably they should be numbered like other "go-anywhere" units (2xx or 6xx), leaving the 3xx, 4xx, 5xx and 7xx blocks to identify units that cannot go "off the juice".
That’s been explained before a few times, it’s just that 700-799 was originally solely for EMUs at the time the 777s were allocated. Splitting the 7xx range into 2 parts was to be a future amendment to the standards.
2xx is still for DEMUs, and 6xx is for basic DMUs - if any are ever ordered.
 

XAM2175

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I did read somewhere that the gaps in the 3xx series, and the new 6xx,7xx and 8xx blocks, were necessary to avoid unit numbers duplicating individual vehicle numbers (BR wagons always had six-digit numbers, although coaching stock was until recently five digits).

But then we see that individual vehicles of:
class 331 have been allocated numbers in the 4651xx and 4660xx series,
class 385 in the 4440xx series,
class 701 in the 4840xx series,
class 717 in the 4560xx series,
class 720 in the 4501xx and 4505xx series,
class 745 in the 3131xx, 3320xx

All of which duplicate numbers already allocated to complete units
You have misunderstood, sorry - vehicle numbers and multiple-unit numbers are kept separate and can be duplicated. The prohibition on duplication explains the gaps in locomotive class numbers, because they have to avoid ranges used for passenger coaches and MU vehicles.
 

RealTrains07

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and 6xx is for basic DMUs - if any are ever ordered.
Makes sense considering we have run out of 1xx numbers. The last being 197.

I guess you could argue since the diesel trains that are numbered in the 7xx range are either bio modes or tri modes, they still can run on electric anyway?
 

YorksLad12

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That’s been explained before a few times, it’s just that 700-799 was originally solely for EMUs at the time the 777s were allocated. Splitting the 7xx range into 2 parts was to be a future amendment to the standards.
2xx is still for DEMUs, and 6xx is for basic DMUs - if any are ever ordered.
6xx is also for HMUs, according to June's Modern Railways (p55) - the Breeze units converted from class 321s.
 

Energy

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The numbering system is random because its up to the operator to decide the number in the range so they go with the number which is most marketable. That's why the class 777s are classified that way despite not being bimode, at the time Merseyrail were told to pick a number in the 700 range so chose the nice 777, the bimode rule hadn't come about yet.
 

Ribbleman

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The numbering system is random because its up to the operator to decide the number in the range so they go with the number which is most marketable. That's why the class 777s are classified that way despite not being bimode, at the time Merseyrail were told to pick a number in the 700 range so chose the nice 777, the bimode rule hadn't come about yet.
It was actually Merseytravel, as owners of the units, who were given the choice.
 

Mikey C

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It was actually Merseytravel, as owners of the units, who were given the choice.
But then that's presumably because they were given a choice of any number between 700 and 799! If they had been given a choice between 700 and 749 (or 386 and 389 or 8510 and 8519) they would have picked a different number :D

If nothing else, surely the families of EMUs could have been kept together, instead of having for example
Desiro Cities - 700, 707, 717
Aventras - 701, 710, 720, 730 (and 345)
 

SouthEastern-465

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I stand to be corrected, but I'm sure in BR days the TOPs number rules were:

1xx - DMUs

2xx - DEMUs

3xx - AC/Dual Voltage EMUs

4xx - Southern Region EMUs

5xx & 7xx - Non Southern Region EMUs.

Probably not relevant in today's railway scene mind.
 

abn444

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There's a bit of a pattern in that it's mostly 7x0 for the Bombardier units and 7x7 for the Siemens units. The main difference being that 700 is a Siemens product (although didn't the DfT run the bidding process for that and it happened to be Siemens that won, could it still have been 700 if Bombardier had won?) That could explain why the SWR Aventras got 701, given it's the closest they could get to 700 given that 700 was already taken. There's also a bit of a pattern so far with the Stadler units in that they've gone 7x5 so far
 

swt_passenger

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6xx is also for HMUs, according to June's Modern Railways (p55) - the Breeze units converted from class 321s.
I think it was “Multiple-unit sets powered by diesel and/or other fuels”
So “self powered” in the recent DfT jargon.

I stand to be corrected, but I'm sure in BR days the TOPs number rules were:

1xx - DMUs

2xx - DEMUs

3xx - AC/Dual Voltage EMUs

4xx - Southern Region EMUs

5xx & 7xx - Non Southern Region EMUs.

Probably not relevant in today's railway scene mind.
At that time 7xx was not defined. AIUI 6xx, 7xx, and 8xx were all new ranges at the same time, just before the 700s were allocated. Back then we had a regular poster who worked on Thameslink and insisted the new range was only going to be for similar long fixed formation EMUs, eg 8 or 12 car, which was quickly discovered to be rubbish, but back then you could look up the relevant rail group standard online, without registering…

But as you say, only of historical interest.
 
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D6975

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Makes sense considering we have run out of 1xx numbers. The last being 197.

I guess you could argue since the diesel trains that are numbered in the 7xx range are either bio modes or tri modes, they still can run on electric anyway?
We haven't run out of 1xx numbers. Once a class is fully withdrawn, the class number can be reused after a certain number of years has passed. Two obvious examples are class 43, originally the AIA-AIA Warships, later HST power cars and class 70, originally the SR electrics, later the GMs.
 

43096

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We haven't run out of 1xx numbers. Once a class is fully withdrawn, the class number can be reused after a certain number of years has passed. Two obvious examples are class 43, originally the AIA-AIA Warships
You mean North British B-B "Warships"
, later HST power cars and class 70, originally the SR electrics, later the GMs.
You mean GE, not GM.
 

PTR 444

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TOPS numbering is a complete mess.

3xx is dedicated to AC and dual voltage units, but most of the 377s are DC third rail only. 4xx is for Southern Region third rail, but 444s and 450s can have an AC pantograph fitted so strictly speaking they should be in the 3xx series. 5xx is for DC outside the southern region, but as such active units in the category are so rare, they may as well be classified with a 4xx number while 5xx gets reserved for something else.

Don’t even get me started on 7xx. Free market means that you have a mixture of bi-modes, tri-modes, battery, third rail only etc with such classification, and its not logical for this haphazard way of number allocation to exist when you’re trying to work out the difference between mode types. I’ve said this on another thread, but if a unit is third rail only, then it should be classified as a 4xx, not a 7xx as is the case with the Bombardier Arterios.
 
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southern442

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TOPS numbering is a complete mess.

3xx is dedicated to AC and dual voltage units, but most of the 377s are DC third rail only. 4xx is for Southern Region third rail, but 444s and 450s can have an AC pantograph fitted so strictly speaking they should be in the 3xx series. 5xx is for DC outside the southern region, but as such active units in the category are so rare, they may as well be classified with a 4xx number while 5xx gets reserved for something else.

Don’t even get me started on 7xx. Free market means that you have a mixture of bi-modes, tri-modes, battery, third rail only etc with such classification, and its not logical for this haphazard way of number allocation to exist when you’re trying to work out the difference between mode types. I’ve said this on another thread, but if a unit is third rail only, then it should be classified as a 4xx, not a 7xx as is the case with the Bombardier Arterios.

Additonally, I would have put all bi-modes and tri-modes into the 6xx region, as they function essentially as DMU's with their 'go anywhere' capabilities. Currently the 6xx range is reserved for 'diesel and alternative fuel', yet all bar 2 new build DMUs have been put into the 1xx range. The only class in the 6xx range at the moment is the class 600, and it's currently possible that nothing might come of that project.

As far as the 8xx range goes, it kind of makes sense, but I think it'd be neater to have a section in each group for intercity stock. Sort of like we tried to do with 37x and 39x before those classifications got infiltrated with other units, so a 67x or 69x for bi-mode intercity and 77x or 79x for electric. Just an idea, but again the 8xx range does at least have some sense to it.
 

YorksLad12

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As far as the 8xx range goes, it kind of makes sense, but I think it'd be neater to have a section in each group for intercity stock. Sort of like we tried to do with 37x and 39x before those classifications got infiltrated with other units, so a 67x or 69x for bi-mode intercity and 77x or 79x for electric. Just an idea, but again the 8xx range does at least have some sense to it.
8xx almost makes sense apart from the 805s, which should really be 806s. That way you'd have had:
  • even numbers for bi-mode (800, 802), odd numbers for electric (801, 803, 807)
  • 80x for 26m-long carriages, 81x for 24m-long
Close, but no (flying) banana.
 

JonathanH

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8xx almost makes sense apart from the 805s, which should really be 806s
805 for 5 car, 807 for 7 car might just be more helpful to operators than what you are suggesting.

However, given the way the 800, 801 and 802 subclasses are organised, I doubt it really matters.

I suspect that the 7xx numbering doesn't perplex operators at all.
 

Mat17

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We haven't run out of 1xx numbers. Once a class is fully withdrawn, the class number can be reused after a certain number of years has passed.
To be fair there's still plenty of 1xx numbers that weren't used the first time around. Many gaps in the 130s, 145-149 numbers.

As you say, the numbers below 130 are all technically vacant on the mainline.
 

driverd

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Makes sense considering we have run out of 1xx numbers. The last being 197.
Serious question - was this sarcasm? If not, what about Class 186-194? 198/199?

Moving on slightly, does anyone know why northern opted for class 331, rather than say, 731?

No objections from me, to using the 'old' formula for emu numbering as it personally feels the more 'proper' way to do things - but I am curious, as using the 7xx series seems all the rage now.
 

Neptune

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I’m still not sure why so many people think we’re running out of 3xx classifications. I can’t be bothered working it out yet again but on a previous thread I think I worked out somewhere in the region of 48 or 49 are still available in the range.
 
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