I did a 5 mile detour at Brampton once, only to find it put me on the wrong side of the closure. I'd correctly guessed it was the bridge that was closed, but didn't notice there were two bridges.
Cycling up Mallerstang, I saw that the Birkdale road from Nateby to Keld was closed with no information whether there was an exception for cyclists. I'd have been effin' livid if I'd been going that way, and had to detour via Wensleydale and the Buttertubs, that's an extra 9 miles and 800' of climbing, and even worse if you'd gone up Birkdale first and then had to turn back.