Re: 3 3/4 scale - track gauge?

Hi,

Interesting question.

The answer is no.

Why? The strength of the materials used drops by the area of the cross-section. For instance, the 3.75" scale is 12 / 3.75 = 3.2. Or 1 : 3.2. Since strength is calculated by area, the reduction is 1/10.4 = 9.6% of the prototype.

The volume of the prototype is 3 dimensions for weight so the reduction of the is calculated by 3.2*3.2*3.2 = 32.8 or 1 / 32.8 = 3%.

When the live steam hobby started, 1" high rail was chosen for ease of use. This rail would be 8" height rail in the prototype.

So the arbitrary use of 1" high aluminum rail is standard. So, in one way it was over-engineered by happenstance.

7.5" gauge using 1.5" scale is a reduction in area of 1/64th and in weight of 1/512th. This has a much larger margin of safety than does 3.75" to the foot scale but both are safe on the track.

Doug vV

P.S. you can think of using HO scale flex track spanning a 1 foot wide gap where you want to put a trestle below it. The track does not sag noticeably for the gap even though it is 87 scale feet long. Many have posted prototype washouts where rails sag over a 40' gap.

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