Regrettably some local authorities appear to think they are providing a service with this sort of thing, to whom I am not sure; motorist, cyclist, pedestrian? It makes you wonder about the people who actually do the work, who can presumably see that it is nonsensical; are they so demoralised with cutbacks (LA) or driven by profit (private contractors).
At risk of trying to teach grandmothers to suck eggs, as Graham normally has most bases covered, try looking at
http://therantyhighwayman.blogspot.com/. Civil/highways engineer with an interest in cycling. Has a different take on the subject.