Make it clear for payment roads/bridges
As yandex navi has this option you can do the same. when we calculate the route, you can offer 2 or 3 routes except the payment route so we can choose if we wanna pay or other way. i got fined 80£ and i didn't know about that. it should be clear like HEY! THİS İS A PAYMENT ROAD! OMG FCK YOU CHOOSE THE WRONG ROAD. YOU GONNA PAY FOR THİS! DONT FORGET TO PAY!
even can be some notifications "did you pay for it or you gonna be fined! " I don't know man check yandex.navi they have great system about that. just make it clear i didn't even know that bridge was for payment. fck.