Some background

Locomotives all look the same, so it’s not like you can tell a train driver “you’re driving the red one today” – you need a way to tell them apart. Enter a favourite topic of trainspotters – numbering systems.

Each locomotive gets a number – and most of the time locomotives of the same type get numbered in the same series of numbers, and either the first few digits or some letters in front indicate the ‘class’ of locomotives.

And from there the numbers get to track maintenance for a given unit, and allocations of locomotives to a given service. Initially these processes were were all paper based, and undertaken by an army of clerks back at head office.

PROV image VPRS 12903/P0001, 287/09

But in the 1970s there was something new sweeping the world of business – computers.

Photo by Oliver.obi, via Wikimedia Commons

And over time, railways around the world also decided to adapt their existing processes to the new world – but not without trouble.

Number shuffling at Australian National

In 1980s the Australian National Railways Commission – operator of freight and passenger trains from Adelaide towards Western Australia, Alice Springs, Broken Hill and Victoria – introduced the ‘Traffic Information Management System’ (TIMS) to make their railway more efficient.

Photo by John Masson, via Wikimedia Commons

Their 1984/1985 annual report stating

Implementation of AN’s computerised wagon monitoring system will dramatically increase utilisation of wagons and locomotives. A sub-system to maintain a comprehensive on-line rollingstock inventory was implemented in October 1984. Partial implementation of the remainder of the system occurred in July 1985, with full implementation due in December 1985.

As part of this, ‘check digits‘ were added to the existing fleet number of each locomotive, wagon and carriage, so that if a number was accidentally mistyped into the new system, the computer would know it was wrong, and prompt the user to correct it.

Australian National annual report 1985/1986

But there was also a problem – locomotives inherited from the South Australia Railways had been numbered as numeric ‘classes’ – where the class leader had the same number as the class name, for example ‘830’ class locomotive ‘830’ and ‘930’ class locomotive ‘930’ – and the new computer system was not able to handle the duplication.

So the solution for Australian National – renumber the class leaders! The next spare numbers were at the end of the existing number groups, so locomotive ‘830’ was renumbered to ‘875’, locomotive ‘930’ became ‘967’, and so on..

And a real doozy in New Zealand

The New Zealand Railways were a relatively early adopter of computers, with their ‘Traffic Monitoring System’ introduced in the 1970s.

Photo by GPS 56 from New Zealand, via Wikimedia Commons

Wikipedia has this to say about it.

On 12 February 1979, NZR introduced a computerised “Traffic Monitoring System” (TMS) nationwide. Implementation was completed in December 1980.

A pilot scheme of TMS began in 1973 on the Palmerston North – Gisborne Line between Woodville and Gisborne. TMS resulted in an 8 per cent improvement in wagon utilisation. In 1977, NZR decided to implement the system out across the entire network. Using dual IBM System/370 systems, one in active standby mode, the TMS system became a centralised system for tracking all wagon and locomotive movements.

As a result of the introduction of TMS, NZR identified that it could reduce its total wagon requirements by 10 per cent of its 1980 fleet, resulting in the withdrawal of many older wagon types. NZR later sold its expertise and some of the TMS software to Victorian Railways in Victoria, Australia and the State Rail Authority (SRA) in New South Wales, Australia.

But the historical New Zealand Railways locomotives classification scheme that relied on superscript characters (eg: D^A and E^W) didn’t work on the new computer system, so the classes were changed to machine readable uppercase characters (eg: DA and EW).

But that wasn’t the only change – the decision was also made the renumber the entire locomotive fleet, across new number groups, with new numbers, in a system completely unintelligible at first glance – four digit non-sequential numbers. An example is the DC class locomotives of 1979 – 85 were built as D^C 1551 through 1599, but now operate as DC 4006 – 4951. So what gives?

The first secret behind the system is the meaning of each digit – the final one is a check number, giving DC class locomotives 400 through 495 – which sounds somewhat sensible, other than the fact only 85 DC class locomotives were ever built, so there’s 10 extra numbers in the series.

The answer to that mystery – I found it on a British railway forum, of all places.

The New Zealand check-digit system doesn’t work like the UIC/EVN system – it’s more complex, not least because it has to cope with vehicle classes which are letters, and variable-length numbers. The way it was explained to me (nearly 20 years ago, so it’s a bit hazy now) is that the check digit calculation can come up with a number between 0 and 10 – not 0 and 9 like the EVN. When it’s a 10, there’s no way to handle it in the computer system, so that number is just rejected and they skip to the next one. So, yes, there are gaps in the fleet number sequence, and that’s just how the system works. The New Zealanders are used to it, and don’t expect to have a continuous list of numbers.

So that’s two layers on indirection in the New Zealand rolling stock numbering system – my brain hurts.

Further tools

• Railways of Australia check letter calculator at Comrails
• TMS check digit calculator at NZ Rail Photos

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