Why are some numbers on the 710s skipped/missing?

[Krystal]

The fleet list for the LO Class 710s are as follows:
- 710101-710130
- 710256-710273
- 710374-710379

Which raises a question. What happened to trains 31-55? Is there an explanation as to why they are just skipped?

 

[Peter Mugridge]

The fleet list for the LO Class 710s are as follows:
- 710101-710130
- 710256-710273
- 710374-710379

Which raises a question. What happened to trains 31-55? Is there an explanation as to why they are just skipped?

710 256 - 710 379 are one series with allowance, likely to never be used, for making the 2xx up to 5 car units.

There's probably, therefore, some other allowance for the big gap that you highlight? Possibly a fleet that has never materialised? Can't be anything to do with the 378s as they're in a series from 01 to 57 inclusive.

 

[43096]

There's probably, therefore, some other allowance for the big gap that you highlight? Possibly a fleet that has never materialised? Can't be anything to do with the 378s as they're in a series from 01 to 57 inclusive.

Allowance for an extra 25 AC only units?

 

[D365]

I recall at the time of delivery that there was an option for additional AC only units, as per @43096 above. What I don't recall is where/how these additional units would have been deployed.

 

[Tony2]

Historically multiple unit fleets with the same operator have attempted to ensure the last 3 numbers are unique, to reduce the chances of a driver picking up the wrong unit.

So maybe an avoidance of the LO class 378 suffix numbers? There are a couple of overlaps though, only a few probably reduces the chances of a mistake.

378135-154
378201-234
378255-257

 

[D365]

Historically multiple unit fleets with the same operator have attempted to ensure the last 3 numbers are unique, to reduce the chances of a driver picking up the wrong unit.

So maybe an avoidance of the LO class 378 suffix numbers? There are a couple of overlaps though, only a few probably reduces the chances of a mistake.

As per the two posts above yours, we don't believe that this is the case.

 

[Tony2]

As per the two posts above yours, we don't believe that this is the case.

My point was that the last 3 digits are uniquely relevant not the last two. Easy enough to remember ‘take out unit 135’ rather than take unit 378135.

In BR days units used to display the last three numbers of the set only.

How set numbers integrate regionally explained very clearly on this Wikipedia page:

https://en.wikipedia.org/wiki/British_Rail_regional_multiple_unit_numbering

 

[D6975]

I recall at the time of delivery that there was an option for additional AC only units, as per @43096 above. What I don't recall is where/how these additional units would have been deployed.

There was an option for a further 249 vehicles on the original order, which was only partly taken up.

 

[MCR247]

Historically multiple unit fleets with the same operator have attempted to ensure the last 3 numbers are unique, to reduce the chances of a driver picking up the wrong unit.

So maybe an avoidance of the LO class 378 suffix numbers? There are a couple of overlaps though, only a few probably reduces the chances of a mistake.

378135-154
378201-234
378255-257

In the cases of the 378s and 710s separately yes, but doesn’t this fall apart since there is both a 378 257 and 710 257

 

[Tony2]

In the cases of the 378s and 710s separately yes, but doesn’t this fall apart since there is both a 378 257 and 710 257

See my post #5, a few overlaps would be a small risk of the wrong unit being taken off depot.

Originally 39 class 710s were ordered, increased to 45 later. This could lead to the number planning anomalies leading to some minor overlaps.