Vehicle Detection for Outdoor Car Parks using IEEE802.15.4

Cruising for parking has negative impact from the economical and ecological points and view, and in overall traffic slowdown. Effective information about which and how many parking places are free could help to reduce these effects. This is possible only if a per parking place motorization is made, which will require the use of sensors to monitor every parking place. While the placement of sensors in indoor car parks is an easy task, usually are used ultrasonic sensors attached to the ceiling, the same is not true for outdoor car parks. Not having a ceiling or a similar structure over (most) outdoor parks, sensors must be placed on the ground. This means that ultrasonic sensors are not the most suitable for this type of application, because their performance might be compromised by dirt. Another option is the placement of inductive loops, magnetometers, micro-loop probes or pneumatic road tubes, however its placement in all parking places of a city might be very expensive and its placement will imply rather complex works on the pavement. The approach presented in this paper consists in using wireless communications to detect the presence of vehicles. It is based on the attenuation that the presence of a vehicle will cause in the propagation path between two wireless nodes. As Wireless Sensor Network (WSN) technology IEEE802.15.4 was used, and it was successfully tested in the detection of parked vehicles.