How mad can this all get? Decide on something then rip up the plan for another even barmier one while suddenly disputing costs by tens of billions. Thats £10million worth of Davies Commission dumped. Is it really not possible to build it alongside 09/27 and use that spare land east of the M4 extension into the airport? Think of the savings... no need to disturb M25 and BA HQ and Incinerator Plant etc etc. An M4 Extension tunnel under a runway would cost peanuts in comparison. As for a bridge over M25, give me strength, they'll be proposing tying two runways together next. Oh they have....
Davies report said M25 would have to be lowered 9 feet in order to pass under runway.
Sounds a far simpler cut and cover task than a monumental sized "bridge"to accomodate
runway, two taxiways, service roads, hard shoulders, flower beds, you name it...