How long is long enough?… (N part 5)

The recent blog discussing viewing height prompted Chris and I to ask another question… How much can you ‘compress’ train length whilst still retaining a degree of realism?

Beaver Cove, Englewood Railway. Chris Medland photo (https://www.flickr.com/photos/chris_city/36415299981)

This question was I guess subconsciously floating around inside my head whilst I was watching more of Grant Eastman’s Southern Alberta layout in N scale. For those of you unfamiliar, Grant combines spectacular Rocky Mountain scenery with mainline running creating an incredibly realistic experience for both the operator and casual observer. Of course as with all modellers, even in N scale, despite the size of his basement and length of run possible he runs condensed trains - but they look right… I wonder is there a formula?

You and me both. 

I am really excited about this question because it feels like a fundamental interrogation of perception. How is a comprehension of size proportionate of experience?

Even though many parts of the SAR are condensed the railroad is still big. The dimensions of so many of it’s parts are physically large. We think of N scale as being small because a forty foot boxcar is just under four inches long or because a model person is maybe half an inch. Everything about the SAR is big but still condensed. Is that sense of right length inherent? Because his passing sidings are still well over twenty feet in length and that’s the size of the room I’m typing this from! It’s like there’s a threshold of what our eyes can measure and once we’re past that point our comprehension of space becomes way more subjective.

Chris pointed me at another older YouTube video by Mark Dance, where Grant mentions his compression ratio, working on no more than 40%… surely it can’t be that simple? In search of a more scientific approach (I’m an Engineer after all) I began to look into field of vision and postulated it came down to two fundamentals:

• How long are the prototype trains you’re modelling?
• How close do you view your models in normal operation? 

Remember my blog discussing the marriage of space to prototype? I think that is the first principle. Then we add the question of viewing height. Now we’ve considered our physical space and our prototype we’re ready to consider a compression ratio. Starting with the basic principle let’s look at the textbook diagram for field of vision…

What we’re most interested in is ‘standard limit of sight’ and using some basic trigonometry I’ve considered this as a ‘visual limit of length’. 

Visual limit of length = The most train we can see without moving our head

And

Field of vision = the further we step back from our subject, the larger the visual limit of length

…moving our view has the effect of disconnecting us from the subject and that means we find it more difficult to judge the models overall length. Basically… as long as our trains are longer than the visual limit, then they can be as long or short as we need, they’ll basically feel ‘right’. Combine this with scale we can see that in N our visual limit will always mean we can see a longer train than H0… in our mind they’re longer, as we see them as long… 

Taking a look (no pun intended) at Beaverbrook as an example, I am viewing this up close meaning my train of one locomotive and 3 cars feels about right as it is close to filling my ‘visual limit of length’, so despite the increased compression (typical trains are two locomotives and 6~ cars) it feels right.

Considering what this may mean for Englewood, typical trains to Beaver Cove were equivalent to 40 x 60’ cars, which would be nearly a whopping 16ft in N scale! Taking Grant’s 40% compression means around 16 cars or a touch over 6ft. Compare this to our science? At a 2’ distance, probably typical if we watch the train by walking around the layout we’d need a train that was at least 7.5ft to fill our view, so perhaps 40% isn’t quite the magic bullet. It works for Grant’s prototype where trains are in excess of 100 cars as the 40% he uses puts their length well beyond our ‘visual limit of length’ but shorter prototype train lengths must be carefully considered using a more scientific approach. This will be taken further in a specific conversation about Englewood’s scheme.

It's almost like a proportion like "40%" is a function determined at the outset of planning. As you're working toward this factor is unique to every layout design. Even within a scene it might be altered so that it's not always a strict 40% applied to everything. Mainlines and the trains that move across them might be 40% length but a yard or industry could be uncompressed. Somewhere there's a middle ground in that spectrum of interpretation; so that space and time move at different rates relative to the experience in that part of our layout.

In the more common model railway we rely heavily on view blocks to obscure the trains and suggest they’ve travelled somewhere or to act as a kind of visual punctuation to break one scene into several. How are they affected when the trains and their scenes approach these lengths? That is in this presentation it’s more important that we are given a place to watch the train in motion and enjoy how it interacts with the scene.

In smaller layouts I find I like thirds. That at a minimum I like the visible scene to be about three times the median train length so we can see the train enter and be contained in the scene (first third); train be in the scene (second third); train leave the scene (third third). These thirds don’t need to be the same length and I think I prefer them to be asymmetrical.

I think Chris is on to something here, and it harks back to our earlier series on small layout success. If we consider this in relation to my Englewood scheme, with a train length of around 6-7ft, I would need to have a continuous ‘scene’ of at least 20ft to enjoy a long train in its environment. That doesn’t mean it needs to be all visible all the time, only that it must travel around 20ft without breaking into another scene. In larger schemes we’re trying to blend science and artistry to evoke an emotional connection to a train in a landscape - there are plenty of ways to compose your model. 

So in summary:

• Our prototype determines the length we’re trying to represent
• Our ‘Visual limit of length’ is determined by how closely we view the trains, but also why N scale trains feel longer (they are, obviously)
• Our compression is dependant on both of these factors
• Our composition is informed by our train length and our scene compression.

I hope that through our thoughts and conversation Chris and I have shared that bringing both elements to bear in your design will help to make it a success. Until next time, more soon…

Chris recently has posted a set of 3 questions over on Prince Street that he posed to me about Englewood. I love the sense of conversation in these blog posts, and the way the two blogs are almost talking to one another too, go take a look…