On 20/03/18 21:06, Jim K wrote:
"Sadly, I've not been able to find an "Earth's curvature compensation"
figure for the slightly shorter Severn bridge (1 mile span versus the
Humber bridge's 1.4 mile span),..."


WEll its a simple exercise in trigonometry, and teh accurate
appropximate answer that the difference is proprtional to the fraction
of the earths circumference, which is about 26,000 miles. So over 1 mile
the vertical 'error' is one 26000th of a mile, or around 2.5 inches.




Hence my question - why would anyone bother being*that* precise
building a mile long bridge?

Because a 2.5" step is emogh to blow a tyre going at 70 mph?

--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

Ayn Rand.