Inductive Loop Detectors: Innovation of Intercepting Traffic Vehicles

by | Jun 25, 2021 | Automative, Business, Commercial | 0 comments

Have you ever wondered how traffic vehicles are detected or intercepted for speeding, running the red light even in heavy traffic? As civilians, I’m sure all of us asked at some point how the traffic lights function, how the system detects when the right time is for the red, yellow, green lights, how the system just knows when it is time to let the pedestrians cross. But most of us pass through as the green lamp gives us the signal of moving traffic, rushing towards our work before we can put too much thought into it. 

The truth is, with growing urbanisation and an increasing number of vehicles per family, where each member owns a car, having a properly functioning traffic system is more important than ever to have a properly functioning traffic system to keep everything in order. This is so that chaos doesn’t ensue during high-velocity traffic hours (like the office rush hours, for example) by ensuring that vehicles stop in the junctions and intersections of traffic hotspots for a while. 

Main Functions of Inductive Loop Detectors

This is where the ingenious innovation of Inductive Loop Detectors work its magic. This is a highly efficient and reliable managing system that senses the flow of traffic. A traffic flow sensor like an Inductive loop detector works by sensing the vehicular presence and reporting incidents, classifications of vehicles, vehicle volumes on the road, thereby controlling the signals accordingly.

There are two types of traffic flow sensors, intrusive and non-intrusive. Inductive loop detectors fall in the former invasive category, and they are used widely in the modern traffic control system. These inductive loop detector mechanisms are usually buried under the road with above ground systems like mounted units over signal heads or pedestrian push buttons. The inductive loop detector capacity is measured either by the number of coils or the core around which the coils are wrapped. 

The main functions of traffic control mechanisms like inductive loop detectors include – 

  • Controlling the duration of traffic lights
  • Identification of a vehicle stopping in red light
  • Identifying if traffic is stacking up at a particular signal.

How Does An Induction Loop Detector Function

Suppose you are interested in the technical details. In that case, the most straightforward hint is in the name itself, i.e., the Induction Loop Detectors function through detecting and observing the changes in induction. The induction is created through loops inside by producing and discharging of current.

Assuming you are wondering what releases the current at a traffic signal. To make it simpler, once a heavy metal object like a vehicle slows down at a red light, they trigger and open the induction loop detector buried under the road, which causes an induction change by releasing current, increasing the resonating frequency. This is the increased frequency detected as a trigger signal that alerts the system of a vehicle stopping at a red light.

These kinds of trigger signals can work on several types of vehicles such as a gate, audio intercom, and the discussed one here and traffic lights.  A common misconception is that loops placed under the carriageway work based on the vehicular weight and pressure; in fact, it is false as they work by detecting the metal of the vehicles by triggering the magnetic field of the loop.

Shortcomings of Induction Loop Detectors

Although Induction Loop Detectors are one of the well-known traffic control devices, they are not infallible. For example, the sensors do not work precisely when vehicles are moving parallelly in the same loop zone or if there are varying types and weights of cars running on the same patch of road.

The most commonly used Induction Loop Detector is pre-formed subterranean thermal vehicle loop sensors. 

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