In reply to marsbar:
> I totally disagree. There are multiple signs counting down for several miles to the crossing and they clearly state that there is a charge between six and ten and that you need to pay online by midnight the next day.
> I don't think it could be much clearer.
Try approaching from the A2/M2, in the dark, and the rain, with leaves on the trees.
There certainly are signs but most of them are quite subtle and blend into the general mess of signage and lights. I was looking and the only one I saw which had the word "pay" was the one after the crossing which said "pay by midnight tomorrow".
As a Brit who already knows about the need to pay (indeed I'd set it up in advance) it wasn't a problem but a foreigner wouldn't stand much chance. The internationally recognised word is "toll" and there really isn't a reason that couldn't have been used. Better still a price board would really draw attention to the need to pay, but that's not what they want is it?