This is shameful. Lincolnshire is hardly overflowing with prehistoric monuments, making this one all the more important. People won't even walk round the corner to local shops though, so I don't think the road-building will stop any time soon (I am heartened by the renewed interest in trains for transporting freight).
I'd love to have a great suggestion for how this can be stopped, but the most depressing thing is that you just know that it won't be.