le Viaduc de Millau - the tallest bridge in the world

[tweak'e]

I'm surprised the piers and pylons were not constructed completely out of steel, is concrete a lot cheaper than steel? I would have thought flexibility would be very important in this sort of construction.

concrete is quicker and cheaper to build with. ie you can pour it and end up with a very large seamless piece. where as steel you have to move small sections into place and join it. all the joins are critical failure points.
its all about using each material at its strengths.

steel requires some intricate design to make it stiff enough which in turns makes it substantially harder to build when building large structures.

[zqwerty]

Thanks for that info.