what do you mean by 'high fine grids' please?

Jumping in here, I took this to mean that the "boxes" with the highest fines for being blocked, are marked with a grid of diamonds - just speculatin'.

I always thought it was just a (possibly written, possibly not) "rule" of driving, that you don't drive into an intersection you can't leave? Or maybe I'm just an exceptionally perlite driver.

hahahahahahahaha! Whew, that was funny!