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 finger tips 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 - born 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.
Darlow Smithson Productions