T&N thanks for your authorative assessment. The 3rd runway (to remain flat and no ski jump take offs) requires a tunnel for the M25. Hence travelling north on the M25 leaving the tunnel on the up gradient the trucks will continue their ascent over the current M4. It is proposed on such short steep gradients a crawler lane maybe required, though I suspect in the peak hours most traffic will be stationary. A tunnel also requires an alternative route so hazchem avoid the tunnel. What right does private company have to ask for a motorway, the A4, and a secondary road north/south to be moved for their profit?
Druk, thanks for your input on the other traffic flow.