I don't even know if the question is correct 
Basically what i want to know is how do the Motorway Staff Calculates the Toll.
when you Enter in M2 they give you a card with magnetic strip on it which they swipe and then you swipe it on exit as well and then it tells you how much you have to pay.
how does it calculate the amount that you have to pay?
Does anyone know that? If you do. Please Enlighten me 