How do railroads come up with their locomotive numbering systems? Is there a any pattern to how this is done by the railroads or do theyjust decide how they want to do it on their own?
In most cases, locomotives of a given model will all be numbered in the same series. It’s been that way for a long time. If a large railroad is buying a bunch of new locomotives, and there are only a few left in a given number series, they may renumber the old locos into a new series (perhaps vacated by other retirements) so they have enough space. That’s why you’ll see locomotives that have had more than one number on the same railroad. It’s also why UP 844 was UP 8444 for a while - UP wanted 844 for a batch of new locomotives in that series.
Smaller railroads have a variety of methods of numbering. If they only buy one or two locomotives at a time, the road number might be the year of purchase. If they buy a used locomotive, they may just use the same road number as the previous owner. Or they might just serially number them as they acquire them, or, if they have enough to do so, put them in “series” by number.
Back to “big” railroads - they might also split what would appear to be a logical block of numbers. Thus 1200-1250 is one model, 1251-1300 is another.
The possibilities are endless.
UP has so many locomotives that they started using suffixes (UPY1234) to avoid the hassles of five digit road numbers.
I was referring to the overall numbering system of all locomotives.
Are you referring to the Model Designations assigned by the locomotive builders?
In earlier years,the railroads would use the locomotive model number for the
first two digits. For example a GP-30 would be 30xx,a GP-35 35xx,a GE U-23
would be 23xx,etc.
If you are talking about model numbers (GP38, etc) check this thread - it spells it out fairly well: http://www.trains.com/community/forum/topic.asp?TOPIC_ID=69298
If you are implying that there is a standard system for road numbers, there isn’t.