Devices that help detecting vehicles

Due to skyrocketing number of vehicles, Traffic and safety issues are proliferating as well.

In alleviating these issues, ITS (Intelligent Transport System) is playing a prodigious role.

Input for ITS is provided from many forms. One among this list are detectors.

Induction looping detectors are the most commonly used detectors....

As installing these devices intrusively causes many obligations, Non Intrusive Traffic Detection Devices are used. These devices are installed overhead, at a side pole(sidefire), or pushed under the pavement from the shoulder.

The fundamental principles involved in these data collection technologies are:

1) Passive Magnetic sensors

2) Active Magnetic sensors

Above 1,2 : Both use magnetic radiation to record the change in magnetic field because of the passage of a vehicle on the road where detectors are placed.

image source: Freeway Management and Operations Handbook

Inductive Loop Detector System

3) Passive Infrared sensors

4) Active Infrared sensors

Above 3,4: Passive and active infrared sensors use infrared radiation in similar way that of magnetic loops. The change in the energy is detected when the vehicle is passed through the detectors.

5) Passive Acoustic sensors

6) Ultrasonic sensors

Above 5,6: These sensors use sound as the medium to detect passage of vehicular traffic. These methods use distance approach to detect any vehicle passed by.