The original gauge is really 4 feet 8 inches, but the British soon discovered that it caused problems when the wheels were the exact size of the track. The 1/2 inch is added so the fixed axle wheel can have some side-to-side play (which is also why they are sloped) and then cars can go around curves without binding. It was easier to move a rail than recast all the axles.Yes, very interesting! I've always wondered why there was a half inch involved: 4 feet 8 & 1/2 inches, just seems strange to me! Someone has stated that the 4' 8.5" gauge was what the wagon wheels where set at. O.K.; but, still why?
Only coincidence, because the laws of physics don't change through time.I also heard the gauge of modern railroad track was based on the wheel width of Roman chariots.
Unfortunately, I cannot recall the source where I originally read that. I think it was in one of my engineering books, rather than a railroad book.I had never heard that the gauge of the track was opened up to 4'8 1/2' inch to loosen the fit between rail and wheel; but, it sure makes sense!
That was not directed at you, but rather a musing, as it has me now wondering where I first encountered the information. I often take notes, but even the notes get scattered about before I can organize and catalog them. I should just start putting a post-it right there in the text as I go, but even that would dictate knowing which book the post-it is in.I know enough about engineering to know that there has to be clearance between the rails and wheels. I don't need a reference to any book about the subject, as it is easily understood as necessary.