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WMATA Real-Time Parking
Information Feasibility Study
Chapter 6: PILOT PROJECT CONCEPT
Detectors and Sensors
Different types of detectors will likely be used for space level and zone level detection. It
is also possible that the detector types selected for use inside the parking structure may
be different from those used in surface lots. For space level detection in a structure,
many of the currently deployed smart parking systems use ultrasonic detectors. This
type of detector is typically mounted on the ceiling of a facility, often directly above the
space as shown in Figure 6-5. The detector can also be attached to conduit extending
down from an overhead structure.
Figure 6-5 Ceiling Mounted Ultrasonic Detector
A number of approaches could potentially be used for space level detection in the
surface lots. The ultrasonic sensors shown could be mounted to a simple overhead
structure. This is a feasible solution, though it may not be an aesthetically pleasing one.
Structure-mounted ultrasonic detectors may also be subject to operational concerns
regarding snow removal and other maintenance. Video detection is also an option,
although concerns have been raised about the software’s capacity to determine
occupancy as environmental conditions change due to factors such as shadows,
darkness, or snow. Another alternative is the use of detectors embedded in the
pavement, most likely magnetometers.
For zonal detectors in the parking structure, the current recommendation is to consider
the entire parking structure as a single zone, as the layout of the parking spaces makes
it very difficult to account for every vehicle moving between different levels.
Figure 6-6 shows the parking configuration inside the multi-level parking structure at the
West Falls Church Parking Facility.
Page 6-9 June 2009