7) “Surveyors, engineers and architects are never required to factor the supposed curvature of the Earth into their projects. Canals, railways, bridges and tunnels for example are always cut and laid horizontally, often over hundreds of miles without any allowance for curvature.”
When it matters, on large-scale projects, engineers do always take account of the earth’s curvature.
Here is one example where they did exactly that, because such precision mattered.
Look at http://www.slac.stanford.edu/econf/C06092511/presents/TU004_PPT.PDF and search for the word “curvature”.
And another example: When designing the Humber Bridge “the towers, although both vertical, are 34 mm (1.3 inches) farther apart at the top than the bottom due to the curvature of the earth
Here is a technical note for Swiss surveyors telling them how to take account of the earth's curvature..
And another from the USA,
And here is another one.
And a book.
And another book
It looks like surveyors do take account of the curve, and Mr Dubay doesn’t know what he is talking about. Again.