Originally Posted by
Prophead
It's all to do with ground levels really. You can take the runway over the M25 if there is sufficient difference in runway level and road level. I don't know what the levels are in that area but I am guessing it will be the road level that is graded down but rather than a wide cut and cover tunnel they will just put the actual runway width over on supports.
Ah, right. Something similar to where the KFLL runway extension goes over US1, then:
