"Being a Blue Belle, an American and a sign nerd, I needed help to translate these signs from Brit-english. My buddies in the UK referred me to this site:

3.4.5"" target=""_new"">http://www.cbrd.co.uk/roadsfaq/#362

Temporary signs, such as diversion routes or direction signs through roadworks, have black text on a yellow background. Recently black-on-yellow signs have been erected in a small number of locations on motorways to draw attention to unusual junction layouts, but this is not standard practice and technically is not permitted.

3.5.4 Why do signs have rounded corners?

Partly this is done for aesthetic reasons, but also because it is less dangerous for engineers fitting them. The New York State Department of Transport changed its policy to using rounded corners instead of squared ones after a number of complaints from its workforce."

It's useful...