TheScullster wrote:


I suppose the question is, are there regulations which cover the "visible
distance" for different road categories (speeds)?
It would be easy to restrict the speed on the slip road to 40mph until after
this junction.


Take a look here, see para 7.3. Is this the information you're looking for?

http://www.standardsforhighways.co.u...on2/td4295.pdf