<P> Dr. Donald Shoup argues that parking meters should have variable prices to maintain an 85 percent occupancy rate . This would facilitate an optimum turnover of vehicles resulting in an optimum turnover of customers for roadside shops . It would also reduce the amount of time wasted looking for a place to park . The SFpark system in San Francisco follows this recommendation . </P> <P> In the US states of Texas, Maryland, California, Massachusetts, Utah, Virginia, and the whole of the European Union (except many private car parks in the UK and possibly elsewhere), holders of a Disabled parking permit are exempt from parking meter fees . In some other states handicapped parking meters exist, which not only must be paid at the same rate as regular meters, but one will also be subject to receiving a violation ticket if a valid handicap license plate or placard is not displayed on the vehicle . </P> <P> Some cities have gone to a device called a Parkulator, in which the users purchase a display device, usually for $5 or $10, then load it with as much time as they care to purchase . They then activate the device when they park at a location, and place the display device on their dashboard so it is visible from the front windshield . The device counts down the time remaining on the device while it remains activated . When they return, then the clock stops running, and the person does not overpay for time unused . In the UK, it is now possible to park and pay with credit or debit card through a dedicated telephone service . Civil Enforcement Officers that patrol the parking area are automatically informed through their handheld devices . </P> <P> An In - Vehicle Parking Meter (IVPM) (also known as in - vehicle personal meter, in - car parking meter, or personal parking meter) is a handheld electronic device, the size of a pocket calculator, that drivers display in their car windows either as a parking permit or as proof of parking payment . Implementation of IVPM began in the late 1980s in Arlington, VA, and is spreading to campuses and municipalities worldwide as a centralized method of parking management, revenue collection, and compliance enforcement . There have since been similar adaptations including the Comet and SmartPark by Ganis Systems, EasyPark by Parx (a subsidiary of On Track Innovations), ParkMagic by ParkMagic Ireland, iPark by Epark, and AutoParq by Duncan Industries . Another technology offers the possibility of reloading money (parking time) to the device via a secure Internet site . </P>

Where does the change go in a parking meter