Model Railway Scale Speed Calculator

by Andrew Allardyce

I was asked by one of our members about scale speeds, how fast should model trains actually be run, but I did not know the answer.   A Google search threw up an article by Andy Watkins of the 16mm Narrow Gauge Modellers e-Group.   Using the basis of his article I have produced the following which may of use and interest.

Most model trains are driven much too fast.   Get to the end of the line too soon, or once around the circuit too fast, and your railway will seem even smaller than it really is.   Slow is realistic.   Slow is prototypical.   The speed limit under the Light Railways Act was just 25mph. (remember the scene in the Titfield Thunderbolt, when the enthusiasts were warned not to go too fast…?).   I know from my experience as a Guard on the Strathspey that 25mph can be quite a good speed to travel along at, although the engines do no not have speedometers!

So how slow is slow?   Being a Physics teacher (retired) calculating speeds is my ‘bread and butter’.   Speed is a combination of time and distance, usually expressed as miles per hour.   A mile is 1760 yards.   Converting this to scale distances, depending which gauge you are running, a scale mile converts to (rounding off to whole numbers)

  • 0 Gauge – 121 feet
  • 00 Gauge – 69 feet
  • N Gauge – 35 feet

Now the Club’s new 00 layout occupies a space of 24 feet by 16 feet.   This would suggest a run of 80 feet, but allowing for the track not being at the outside edge of the board and for curves at the end, a reasonable extimate would be about 75 feet of track to complete 1 circuit so it is just over a scale mile.

But what about scale time?   Time is real.   A real speed of 30 m.p.h. means that it takes 2 minutes or 120 seconds to cover 1 mile.   If it takes 120 seconds to cover a scale mile of 69 feet, divide 120 by 69, and you will see it takes 1.7 seconds to cover each foot at 30 m.p.h. for 00 gauge, so a complete circuit of the 75 feet of track on our new layout at a scale speed of 30 mph should take 127 seconds – just over two minutes!

The table below shows how long you should take for different speeds at different scales.

 

Model Railway Scale Speeds Calculator

Speed    /mph

Time per scale mile    /seconds

Time to travel 1′ of board/seconds

Time to travel a 6′ board/seconds

Time to travel a 75′ layout/seconds

0 Gauge

00 Gauge

N Gauge

0 Gauge

00 Gauge

N Gauge

0 Gauge

00 Gauge

N Gauge

10

360

3.0

5.2

10.4

17.8

31.2

62.3

0.0

222.7

389.7

20

180

1.5

2.6

5.2

8.9

15.6

31.2

0.0

111.3

194.8

30

120

1.0

1.7

3.5

5.9

10.4

20.8

0.0

74.2

129.9

40

90

0.7

1.3

2.6

4.5

7.8

15.6

0.0

55.7

97.4

50

72

0.6

1.0

2.1

3.6

6.2

12.5

0.0

44.5

77.9

60

60

0.5

0.9

1.7

3.0

5.2

10.4

0.0

37.1

64.9

70

51

0.4

0.7

1.5

2.5

4.4

8.8

0.0

31.5

55.2

80

45

0.4

0.6

1.3

2.2

3.9

7.8

0.0

27.8

48.7

90

40

0.3

0.6

1.2

2.0

3.5

6.9

0.0

24.7

43.3

100

36

0.3

0.5

1.0

1.8

3.1

6.2

0.0

22.3

39.0

 

Of course, what is right does not always look right is always a good ‘get out clause’!


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  1. Pingback: Model Railway Scale Speed Calculator « Forest of Dean Model Railway Club

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