Broad Gauge

Maximum safe speeds for typical narrow gauge railroads hover around 80 mph. High speed standard gauge lines seem to be hovering in the 160 mph range.

Is there a benefit to using a broad gauge for high speed rail? I realize that you are facing limits on propulsive technology, but assuming that the other pieces were in place, would a broad gauge raise limits over standard gauge?

cloudship wrote:Maximum safe speeds for typical narrow gauge railroads hover around 80 mph. High speed standard gauge lines seem to be hovering in the 160 mph range.

Is there a benefit to using a broad gauge for high speed rail? I realize that you are facing limits on propulsive technology, but assuming that the other pieces were in place, would a broad gauge raise limits over standard gauge?

It is often said that Brunel's 7 ft gauge on the British Great Western would have led to modern high speeds earlier. The main advantage was probably a lower centre of gravity and therefore greater stability, but his lines were also engineered to be level without gradients. I think Cape gauge lines can reach 100 mph in South Africa and Queensland. Ask in the Worldwide section.

yeah , they were doing 100mph in Queensland , bu i think thats been lowered since a crash there a couple of years ago .

There's a theoretical advantage once you go over standard gauge, and narrow gauge systems do in fact tend to have lower top speeds.

But the French have demonstrated operation to over 350mph, and commercial service is at 200mph on some new lines, and soon to be 220mph.

The advantages of standard gauge outweigh the disadvantages, it seems, especially since the French record seems more power limited than anything else.

I suspect you also get diminishing returns, and that the real optimal gauge might not be much wider than standard, anyway. Might make an interesting research project...