The delivery risks of such a massive project including its surface transport links are
very great, and the economic disruption would be huge. No other city has moved the
operations of an airport on anything like the scale of Heathrow anywhere near as far as
would be implied here. There are environmental hurdles which it may prove impossible, or
very time-consuming, to surmount. There are also challenges in relation to the practicality
of operating a very large hub airport in the estuary; for example in relation to airspace
management and the risk of birdstrike. The implications for passengers are unfavourable.
The average rail journey to the airport on opening would be 20-25 per cent longer than is
the case today. Even the least ambitious version of the scheme would cost almost £70 to
£90 billion with much greater public expenditure than involved in other options – probably
some £30 to £60 billion in total. More ambitious schemes would cost considerably more.
While future governments must make their own decisions on priorities we cannot see that
additional infrastructure investment in the South East, on the scale implied, with uncertain
economic beneits, would be likely to appeal to the Chancellor of the Exchequer in a
government of any political colour