How do you calculate scale speed?

Most modellers will not need to calculate scale speed as our passion for railways would undoubtedly have led us at one time or another to experiment with our trains speed on our layouts until we have found one that looks about right, but for others, the quest for realism or the human nature to wonder will be prompting further investigation.

To calculate scale speed you will need a stopwatch, measuring tape and a calculator.

The first thing you have to do is measure 1000 scale feet on your layout and put a marker at the beginning and end of the distance.

The following measurements have been rounded to the nearest centimetre as this is accurate enough:

For 00 gauge: 1000 scale feet is a distance of 400cm (4 metres or 157 inches)

For H0 gauge: 1000 scale feet is a distance of 350cm (3.5 metres or 138 inches)

For N gauge (1:160): 1000 scale feet is a distance of 191cm (1.91 metres or 75 inches)

For British N gauge (1:148): 1000 scale feet is a distance of 206cm (2.06 metres or 81 inches)

Next, you need to time a train running at a constant speed through the marked out section. Start the stopwatch when the front of the train passes the start marker and stop it when the front of the train passes the finish marker.

To calculate the speed of your train, we need the results of your timed run. We also need to know how fast a train would be going if it achieved 1000ft in 1 second. Fortunately we have worked that out already: the answer is 681.9 MPH

 

Now we have both bits of information we need for the calculation, try the following calculation:

681.9 divided by the number of seconds that you have just recorded on your stopwatch.

The answer is your trains scale speed in miles per hour.

The first thing you will notice is how fast the speed that you have just calculated seems in comparison to what your eyes have just witnessed. Indeed we tested one of our own locomotives, as it turns out, a Hornby Class 42 diesel can achieve a scale speed of 170mph, who would have thought? We daren't put our Jinty to the test as it would probably completely ruin our humble opinion of the old girl.

The reason your trains seem a lot slower than their scale speed is all to do with the way our brains work. Our brains are well aware that we are looking at little trains on little tracks and our imagination allows us to enter that world. What it doesn't account for, however, is the real-life distance between our eyes and the layout. If you were observing your time trial from a standing position, your brain would not be able to process the fact that you were in effect viewing your train from a perspective of at least 250 scale feet in the air depending on how tall you are and what scale you are modelling in. It only recognises the reality of your tiny train running along at a very real-life 2mph, less than three feet away. A good example of this when you see a jumbo jet high up in the sky off to somewhere sunny: it never looks as though it is travelling at hundreds of miles per hour but our brain accepts it because we know that it is miles away.

A top tip to counteract this is to try the test again, but this time try viewing your train from eye level, especially if you have got a perspective point on the track, such a station and see what a difference it makes.