[tweetiepooh]

Our local hospital car parks work on number plate recognition. When you want to leave to go to a terminal, enter your reg and it tells you how much to pay. You pay and when you leave the gate opens if your reg has paid. Maybe enter your appointment details as well to link to times you should be at hospital. Visitors can be given codes to coincide with visits. Code could be bar-code or magstrip card.

So surely something can be arranged for staff (approved car reg) and hospital users to access free parking while others can be charged effectively to not let them want to use these car parks.