Wrong way lights

[VNA]

Ok, I'd not considered that, but I can see the reasoning.

In that case, they could try what's been done on some roundabouts here, where there's an outer circle of red "bricks" (or something, that's what they look like) which are intended to encourage people to drive around them, rather than cut across.

If those were put at the entrance, there would still be space for the artics to turn whilst giving the visual impression of a narrow entry.

I have no idea what you are on about.
As it says it's a trial.  I think it's interesting and it might very well be effective.  The idea of the trial is of course to see how effective it is.  It's well worth a shot.