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Traffic Loop Detectors Fundamentals

by | Apr 30, 2021 | Automotive

While inductive loops for traffic detection are a relatively common technology, their physics is complex, involving the ferromagnetic effect, magnetic induction, and eddy currents. Despite their widespread use, inductive loops may be phased out in favour of newer technology due to cost and time constraints.

 After their invention more than 50 years ago, inductive loop detectors have been the most widely used form of traffic detection. They are used to alleviate traffic congestion in the majority of cities. However, how exactly do inductive loops operate? Certain outlets assert that detection is solely dependent on the ferromagnetic effect – they tend to oversimplify the physics involved. This article discusses the fundamentals of traffic loop detectors in Newcastle and delves into how these ubiquitous devices detect vehicles.

Basic Setup 

In general, inductive loops for traffic detection consists of three major components:

  • Two to three turns of wire under the road surface, 
  • A lead-in cable which connects the loop to the detector, and 
  • An electronics device that senses the presence of vehicles above the loop

System Layout

Because traffic loop detectors depend on various complex phenomena to work, proper device configuration is critical to avoiding false triggers or reduced accuracy. The loop must be installed less than 5 cm below the road’s surface; otherwise, the sensitivity will be lost. Additionally, all links are soldered. The lead-in wires are twisted to avoid unnecessary induction. Any metal reinforcement around the region is removed, and no air pockets remain after the wire loops are sealed into the road.

Uses for Inductive Loop Detectors 

Inductive loops for traffic detection have a wide variety of uses, including detecting vehicles at intersections, counting traffic, tracking vehicle speed, and sensing the presence of trains at railroad crossings. At the moment, inductive loops are used to provide information about the density and speed of traffic, which is then used to alleviate congestion.

Alternative Technologies

While traffic loop detectors systems in Newcastle are the most frequently used monitoring traffic conditions, their installation can be disruptive and costly. Additionally, a single loop cannot monitor multiple lanes or detect multiple vehicles. Additional options are being investigated, including installing wireless infrared sensors on lampposts and traffic monitoring via GPS-enabled smartphones. 

These alternatives are likely to be significantly less expensive and simpler to install than inductive loops. As a result of these factors, inductive loop traffic detection will likely become redundant in the future, though existing loops will continue to be used. However, since it will take several years to develop alternative sensor systems completely, the inductive loop will remain the most widely used traffic detection device for a long period.

Health and Safety

There are few safety concerns with inductive loops for traffic detection. One of the primary issues is that inductive loops can miss motorbikes due to their lack of metal surfaces parallel to the loop. If the traffic light stayed on until activated, riders on motorcycles that failed to activate the loop could be tempted to ride through the red light, raising their risk of a crash. Increased inductive loop sensitivity due to improved signal processing should resolve this problem.

Traffic loop detectors in Newcastle are very complicated devices that operate through magnetic fields, induced magnetism, and eddy currents. They have been the most widely used traffic sensor since their introduction in the 1960s, but that could change in the future as new technologies arise.