On 2011\10\31 09:12, Nightjar wrote:
On 31/10/2011 02:26, Basil Jet wrote:

More data: the brand new layout at Palmers Green has separate lanes for
turning left and right off the North Circular, and the same thing has
been done, i.e the going forward lanes have no signage apart from the
green arrow (and lane markings), and the turning right lanes have a no
u-turn sign but no forced right sign apart from the green arrow. So it's
not a temporary cock up but a systemic failure IMO.

Different junction type and different guidance applies. In the first
case you mentioned, turning is prohibited, so a straight ahead only
arrow would be appropriate.

In this case, turning off the main road is not prohibited, so it would
not be correct to put up signs that show that it is, which direction
arrow signs would do. The road markings are the correct signs to show
that a particular lane is dedicated to a particular direction of
movement and they can be supplemented by an advance warning (get in
lane) sign, if required. In any case, to avoid confusion, there should
be no more than two (or, rarely, three if there are no supplementary
plates) regulatory signs at one spot and there is already a no-U turn
sign at these lights.

Sorry - when I said "separate lanes for turning left and right" I should
have said "dedicated slips for turning left and right".