On Tue, 20 Feb 2018 09:50:00 +0000, Nightjar
wrote:

Removing the centre line is only proven to reduce speeds, by around
5-9mph, where the limit is 30mph or less.


I saw a study which seemed to indicate a grass strip up the centre of
the road reduced speed most, whether this only applied to single track
roads I don't know.

AJH