How to stop them barking at the builders?

[MothershipG]

The next door neighbour is having an extension built, when the builders are on the roof or going past the end of our garden the dogs go nuts.

So if I tell them to be quiet they are, if I'm in the garden with them they can restrain themselves.

How do I move to the next step whereby I don't have to be there? I've read The Culture Clash so I understand why they do this, but how do we get past it?

They like barking, it's a self reinforcing behaviour, they want to warn me of impending Hungarian attack. How can I convince them it isn't necessary???