SS,
And the logic still stands. Separating light and heavy traffic speeds up arrivals to an airport. And so anyone who designs a nice new airport with all the runways so close together that there cannot be any separation, is, well, stupid. Foster included.
As you have correctly pointed out, building an island airport is an expensive operation. Therefore, two sets of parallel wide spaced runways would be far more expensive than two sets of close ones. The terminal should provide sufficient separation to allow simultaneous approaches on each side of it, but all we have for now is a concept sketch, not a detailed plan unless you can give us a link for one?
Its not just about moving Heathrow, there are many businesses around the Thames valley that are there to cater for the airport. The people that work at Heathrow and these other businesses mostly live in and around that area.
Exactly, you are shunting the entire Thames Valley 180deg, and shoving millions of people through London to get to an airport the other side. This isn't just an engineering challenge on the site in question, it presents an enourmous overloading on the surface transport network throughout the SE.
b. Customs and immigration. It is still advantageous to separate domestic (small aircraft) and international traffic (big aircraft), for immigration reasons.
This is surely a matter for the terminal designers - granted, that is more Foster's field, I would be interest to see if Arups have made a public comment on this, I know they have slammed the routing alignments for hs2.
I am still puzzled that you claim to be a 76 jockey. I will admit I am no pilot, but I have never come across the concept of a domestic runway. A runway is a strip of (insert material of choice) - it does not care who is inside the plane, or where it is going. Either the plane can take off or it cannot, based on:
a) The aircraft size / weight.
b) The load, including fuel.
c) Weather conditions.
d) Elevation (obviously not an issue here).
e) Engine configuration.
Now as a general rule, larger aircraft operate longer routes, and international routes are longer than domestic ones, but this is by no means cast in stone. I have done BHX-EWR in a 757, and LHR-FRA in a 767, and let's not even start on Japan!
And I'm sorry, we have to consider a proposal against the politics of now, and even looking ahead, these aren't the EUs best days. Arriving into the UK, you have red, green and the EU blue channels, then you have domestic flights from IOM & Channel Is (not sure about GIB?) subject to customs allowances, not to mention the Canaries, and where do you label Morocco? It all gets very very messy, and that is for the terminal designers to sort out. If there are any specifically designated domestic runways (as opposed to airports restricted to domestic only flights), please do go ahead and name them.