Silver,
Should every UK project give a direct monetry return? Is there a direct monetry ruturn to building the M25, and its subsequent widening? No.
And again, we have been through this before, but for people picking up the thread for the first time, I will repeat, you can't compare a new airport with a road, especially as govt takes in revenue through fuel duty, which airlines don't (and won't) pay, road tax etc, and the last time we did build a new motorway, it was done as a toll road.
Yes, airports enable business links and bring tourists in, but they also export K citizens elsewhere to spend their money. You have to look at the political clamour to impose ever higher rates of APD, not just because of the green lobby, but because it is a nice little earner for HMR&C.
In most cases, UK airports have been able to fund expansion privately, although BHX has had a few quid from regional quangos for its runway extension. Now a lot of use here question how that will get a return, but we're talking £130m v £20-30-40-50+ BILLION for your Silver Island!
Sorry, but I just don't see that happening - I can marvel at the design drawings, but funding has got to come from private sources. Maybe, just maybe, the govt could act as guarantor, but I think the reality is that treasury would say it has to sort itself out, if the island sinks, then developers might come cap in hand for a bailout, and then who knows.
If you will excuse the pun, we really are in uncharted waters, hence I repeat my request - come up with some figures, knock them around a bit and let the PPRUNe Dragons decide whether or not you stay in the Den.
I'll start you off with an average PSC of £50, 100m pax pa gives you £5bn revenue. Any ideas on margins for fuel sales? %age of pax who pick up a hire car and what the airport takes? I know average shopping spend in LGW is just £5.
I'd like to suggest adding in airport hotels, offices etc, something Foster seems to have omitted. On your island, these would need deeper foundations, but if we just stick to a single terminal complex with 2 runways either side, what are the height limits? One giant rectangular based pyramid with an observation deck on level 49 and control tower on 50? How would you evacuate in the event of a refueling fire? Once you go outside this terminal area, reclaiming more land for offices is going to get very expensive.