Surprisingly, it seems that some Roman road culverts round Broadwindsor in West Dorset are still hard at work. This interesting in itself, but the existence of a Roman culvert necessarily implies a Roman road above it which may now be invisible beneath tarmac..
There is a short web page at
which has a link to a longer paper at
If anyone has come across anything like this - they're rather hard to find since the culvert entrance and exit are usually in the fields beside the road and invisible from it - I'd be most interested.