Why is a third runway at Heathrow predicted to cost so much?

Posted by WolfCola4@reddit | AskUK | View on Reddit | 232 comments

This debate about a third runway has been going on seemingly for decades at this point, with recent figures quoted at around 49 billion pounds to build.

Granted, I'm no builder. And I'm aware there's probably a bit more work to put in than in my imagination, which essentially is just tarmacking an especially long driveway. But seriously, 49 billion pounds??