Introducing the C-P-R Principle

Question: Did it ever happen? A question often posed by unsure modellers and railfans, regarding the railways' use of a particular piece of equipment or a particular operating practice.

Answer: Yes it did, or no it didn't. Based on what, though? I've been thinking about something I will call the "C-P-R Principle", to help answer specific variations of the above question, where:

C = Context. When and where? Define what era and what location you're considering. This has to be answered before moving on to the other two parts of the principle.

P = Probability. How likely and how often? If it was just a one-off, probability is low. If it was an everyday occurrence, probability is high.

R = Records. Can we prove it happened? How much proof is there, in what format, and how reliable is it? The more proof, the more relevant and reproducible the model can be.

With the plethora of prototype-specific models, including era-specific detailing on Rapido Trains' FP-9 , those wishing to model increasingly realistic scenes may wish to use the C-P-R principle as they invest and place such models in realistically-detailed scenes.

Let's consider three sample questions to which we'll apply the principle:

1. Did VIA F-units ever operate in the same power consist as CN chop-nosed Geeps?

C = Anytime, anywhere.

P = Unlikely, right off the top.

R = One photo. The Kingston-Belleville wayfreight with GP9RM's 4120-4121 has lifted FP9ARM 6309 which was bad-ordered on the early-morning VIA train, heading west from Queens to Belleville on March 30, 1992. (Top) But wait! More proof from an unlikely source found twenty years later: an online auction slide dated 1992 showing 6309 beside the Belleville roundhouse (above)

The wide-open context, low probability and very little photographic evidence give this answer a low modelling relevance.

2. Did CP Rail MLW's ever operate west of Ontario?

C = 1980's, Winnipeg and west.

P = Most of us usually assume the MLW's were mainly used in eastern Canada.

R = Photos of MLW's in BC coal service in the 1970's abound, but by the 1980's the Centuries were pushed aside by new SD40-2's. I took several photos of Centuries and C424's west of Winnipeg, including 4214-8508 and 106 grain cars westbound at Portage la Prairie on August 28, 1981.

The decade-wide context, low probability but ample photographic evidence give this answer a moderate relevance to modellers.

3. Did CN ever operate GP40-2W's in twos or threes? (OK, this is an easy one, just to test the principle.)

C = Any era, system-wide.

P = With a large fleet over 250 units in three classes built between 1974 and 1976, probability is high.

R = A photo at West Tower, Portage la Prairie on August 28, 1981 with 9401-9624-9407 and 112 cars of TOFC/COFC eastbound, dusty from having run on fresh ballast, one of many photos of members of this type operating together, from almost anywhere on CN lines after 1974.

Wide context, a large number of units and ample photographic evidence give this answer a high relevance for modelling. That's likely why Atlas recently released this model.

Railmodel Journal magazine addressed this issue in an article entitled Operation Evolution: Do scale models deserve "scale operation" in November 1989: The next time you buy a model railroad product, you will not find instructions inside the box about how the railroad is supposed to be operated. The operation of a real railroad is perhaps the greatest intangible hurdle the modeller has to overcome. And, wouldn't you know it, this is probably the largest information void we have from which to draw our operating schemes. The manufacturers offer no help, and the magazines are just beginning to touch on the realities of operation. We have a long way to go , but learning the how's and why's of railroading is far from impossible. So how can we conduct accurate research?

Charles Cooper's Railway Pages list potential sources of records including photographs, track diagrams, railway magazines, railway books, hobby shows, and railway publications, which "interpret the railway scene and place it in its correct historical context as to time, place and function". The authors of these works have often gone to considerable trouble to source the information presented from archives, museums, former railway archives and engineering departments, retired railroaders, and long-standing photograph collections." Charles only briefly mentions the internet, which can include re-posted and incorrectly dated or otherwise altered information and photographs.

For number-crunchers, here's how I would put some relative if approximate numbers on the C-P-R Principle. Treat each part of the principle as a percentage, by estimating:

C-value: Narrow timeframe can still give a high C-value, especially if practice occurred frequently. For instance, 20 incidents in one year or in ten years can still be 100%.

P-value: The actual probability or likely number of events in a given time period. Probability may improve as more research is done. For instance, a daily event (365/year) = 100%, rare event (i.e. 3/year) = 1%.

R-value: As more research is done, the number of records may increase. Statistically, more records give a more relevant and higher R-value. For instance, 1 record = 1%, 10+ records = 100%.

(C-value + P-value + R-value) divided by 3 = Relevance Factor %. If the relevance factor is an acceptably high percentage to you, it will help you decide if the equipment or practice is worth pursuing in model form.

(Or, toss it all out and do what you want - it's your layout and there has to be some fun and spontaneity involved. Run that Royal Hudson with an LRC consist! Tack an ETU onto your 1940's freight train! Yes, I intended to run an RPO and combine on my double-stack train!)