Richard Hammond's: Engineering Connections - (S02E05) Millau Sky Bridge.
Richard Hammond reveals the engineering inspirations behind the tallest road bridge in the world the Millau Viaduct in France.
He fires three quarters of a million volts from his fingertips to see how the power of lightning cut the steel structure quickly and accurately. The huge piers 340 metres high, and which would look down on the Eiffel Tower were positioned to millimetre accuracy with the system that located lost nuclear submarines.
The longest road-deck in the world was launched along the top of the piers and required the slipperiest substance known to man Teflon; not even a gecko can stick to it. Steel cables hold the bridge in shape, borne of a series of mining accidents. And to allow the bridge to expand a metre and a half in the summer sun, the engineers turned to an ancient Celtic boat-building technique which can make concrete as bendy as wood.