It's not a style of intersection that it is very common in the UK where I do most of my mapping but I think you would pretty much have to continue both carriageways to the far carriageway of the crossing road and then start the single carriageway road from there. So something like this: | | --+--+ | +---- --+--+ | | Yes that may then need careful handling when doing driving directions, but so do lots of other things as well.

It's not a style of intersection that it very common in the UK where I do most of my mapping but I think you would pretty much have to continue both carriageways to the far carriageway of the crossing road and then start the single carriageway road from there. So something like this: | | --+--+ | +---- --+--+ | | Yes that may then need careful handling when doing driving directions, but so do lots of other things as well.