Potential Sensors (FINAL): Gem Pressure Switch


A typical way to count cars that pass by is used in every city and highway by a company called W-Trans. The basic use is to measure how much traffic flow there is in a certain area. They go about counting by laying down two rubber tubes in parallel and both perpendicular to the road. These tubes are attached to counting equipment at one end and closed at the other. These tubes use sensors called air switches. The air switch is triggered when a car rolls over the tube. The air in the tube compresses and then pushes towards the nearest exit which would be the air switch.  Two tubes are used to determine from which direction the vehicle is coming from. The road tubes come in different sizes including a Half Round design for 80 mph and up, Standard Round Tube for around 50-60 mph, and lastly the precision mini tube for residential areas. The latter is the tube for us since we will be dealing with cars entering parking lots at about 10 mph. The sensor is the pressure switch which will turn from low to high or vise versa depending on the psi level that we set. When a car rolls over the tube the pressure will raise the psi within the tube to the adjusted level and count up or down depending on if a car enters or exits the parking lot.  Prime Parking’s pressure sensors in particular are from the company known as GEM.  The PSI range these sensors can be calibrated to range from 15 PSI – 60 PSI