Global Positioning Systems

February, 2002

Rapid Parking Equipment Developments Will Determine Our Future

Traffic-related technology is a fast developing science. This has particularly been the case in Singapore, where electronic road pricing and the local cash card are state-of-the-art technologies for road tolling and parking. This technology could, however, be history very soon with additional improvements in service and further advantages for government, operators and, obviously, also for the users.
A new application of the well-known Global Positioning Systems (GPS) could enhance and improve the service, profitability and reliability of the transport network.
Global Positioning Systems: Is it a technology not yet ready for parking?
GPS technologies are proven methods to locate containers, whether at sea or on land, planes, mobile phones for emergency calls and various fleet management applications.
Standalone GPS receivers can achieve an accuracy of approximately 100 feet (30 meters) horizontally. Greater accuracy can be achieved by a differential GPS. The trick to differential GPS is to use a reference receiver station located at a precisely known position and this reference receiver, like any other GPS receiver, knows where the satellites are supposed to be from the orbital data.
Since the reference receiver also knows its own precise position, it can compute the distance to each satellite and divide that distance by the constant speed of light to get the delay time. The receiver compares this computed delay time with the measured delay time and the difference between the two becomes the error estimate of the signal from the satellite. The reference station broadcasts this error estimate to GPS receivers in the vicinity and then uses the data to adjust its position calculations.
With this process, most of the error sources can be eliminated. As a result, precision within about 3 feet (1 meter) can be attained. For surveying receivers even centimeter level can be reached.
The Global Parking Positioning System (GPPS)
A tiny reference receiver, the size of a matchbox, can be installed and officially sealed somewhere in the engine compartment of a vehicle. Another reference receiver with a fixed and known position has to be installed within the car park, close to the entry of the CBD or along the street.
In case the coordinates of the two reference receivers are the same, plus or minus a small tolerance, the GPPS knows automatically the location, the time, the date and the necessary data in relation to the vehicle.
This data can then be transmitted to and from the orbit, as indicated below, applicable fee calculations undertaken and the fee displayed on an in-vehicle display. The fee will automatically be deducted from your account via e-parking.
On Street Parking
The following two-dimensional model shows in general the functionality of the GPPS in an on street parking application.
The distance from the stational reference receiver to the center of the parking lot (blue coordinates) is fixed and known by measurement or calculations.
The variable distances from the orbit to the stational reference receiver (green coordinates) and also the distances from the orbit to the reference receiver of the vehicle (red coordinates) are measured and calculated according to the previously mentioned method.
For a two-dimensional model the two following equations G = E - B and H = A - D are essential, plus or minus an applicable tolerance for the size of the parking bay.
The GPPS will clock-in the time the vehicle is stationary, meaning the coordinates remain unchanged, and will clock-out following a fee calculation once the vehicle starts to move and the coordinates are changing.
Off Street Parking
Very similar to the on street parking solution above, the functionality can be transferred to an off street parking application.
Once a vehicle passes the entry of the car park, the GPPS clocks-in the vehicle with entry time, date and other optional information. After receiving the exit time and the date, the GPPS will automatically calculate the fee, which would be deducted from your account by e-parking/banking.
The above model is two-dimensional and with a three-dimensional model even level counting, nesting areas or a "network" of several car parks can be achieved without any cabling between the car parks.
Due to the accuracy of the whole system, a parking guidance system can also be realized, guiding the driver of the vehicle to the level with available parking bays and, on the specific level, to the bay available.
Season parking with pre-defined car parks and rates can be established with both hourly and season parking working hands-free.
It's cost effective; operates with a minimum of installation and investment cost and a minimum of service and maintenance; is user friendly; hands free for hourly and season parking; and is flexible. One system for all kinds of car parks.
Road Tolling
An application, which might be interesting also could be the road tolling application.
In order to enter the CBD, the GPPS could provide a simple and professional solution compared to current cash card technology.
The only thing the driver of the vehicle would see is signage indicating that a fee is applicable before entering the CBD.

Thomas Pfister is Managing Director of DESIGNA Parking & Access in Singapore with regional responsibility for three years and parking business experience for five years. He has experience in international large-scale projects in the Middle East and Asia, including Malaysia and China. He can be reached at pfister@designa.com.sg.