Detection loops and loop detectors

What is loopdetection?

A detection loop is an induction loop of copper wire that is located in the surface of the road. By connecting the detection loop to a loop detector, a magnetic field is created (electric coil). A vehicle disturbs the magnetic field and is recognized. A detector for a detection loop provides the signal with which barriers, industrial gates and fences can be opened.

Using detection loops

BBC Bircher Smart Access offers detection loops for the automatic opening of, for example, barriers and industrial gates. Detection loops are also used at traffic lights and on motorways. Traffic data can be collected by these detectors to inform and advise traffic.


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Detection loops for loop detection - BBC Bircher Smart Access
ProLoop Lite - Control Unit - BBC Bircher Smart Access

Loop detector - Controle units for loop detection

The BBC Bircher Smart Access Proloop Lite is equipped with the same standard functions as the Bircher Reglomat Proloop 2, including Automatic Sensitivity Boost (ASB). This function automatically sets the detection loop to maximum sensitivity when a vehicle is detected. 
The automatic sensitivity boost can be bery important for passing trucks with trailers. Read more about ASB below.

Frequency settings

The Proloop Lite is also equipped with various frequency settings to prevent interference caused by other loops or sources. The response time of the outgoing signal can also be adapted to the desired application. Read more about ProLoop in the application example.


View Proloop Lite loop detector in the Product Portal


Situation Situation Situation Situation
Use at sliding gate Use at access barriers Application at bollards Access at gates with traffic lights
Parking system sliding gate - Loop detection - BBC Bircher Smart Access Parking system barrier stoplight - Loop detection - BBC Bircher Smart Access Parking system pollers - Loop detection - BBC Bircher Smart Access Parking system barrier stoplight - Loop detection - BBC Bircher Smart Access
Solution Solution Solution Solution
  1. Opening and closing site fencing inside and outside
  1. Opening and closing access barriers at the entrance and exit of parking zones
  1. Activation of retractable bollards at entrances, parking places, roads and pedestrian zones
  2. If the bollard is in use, it prevents improper activation
  1. Operating gates and light signals at confusing entrances and narrow passageways
Advantages Advantages Advantages Advantages
  1. Contactless activation of fencing installation
  2. Reacts to all metal vehicle
  1. The opening impulse of the access barrier can be used as a counter to indicate how full the parking garage is
  1. No collision between vehicle and bollard. Not even after a power failure.
  1. Straightforward traffic control
  2. Purposeful activation due to directional logic function
  3. Shorter waiting times due to optimised traffic flows


Loop detectors - BBC Bircher Smart Access

Loopdetector for industrial vences, barriers and pollers

ProLoop 2

The ProLoop 2 protects and tests in-ground induction loops to detect metal objects and vehicles, such as passenger cars, bicycles, forklift trucks and trucks. The objects are precisely recorded using the ProLoop 2. The galvanic separation between the detector and the loop ensures maximum reliability.

Intelligent, simple, compact

The compact design and intelligent software ensure easy commissioning and operation. The 11-pole connection allows fast installation or replacement of your loop installation by mounting on an existing base. The ready-to-use induction loop is an important part for the sensor system of the loop detector. The induction loop can easily be placed in the road surface or in the ground and is immediately available in 6 and 10 meters.

Benefits ProLoop 2:

  • Fast commissioning
  • Service-friendly and well-organized
  • Individually customizable
  • Integrated measuring device
  • Always programmable


View Proloop 2 and induction lines in the Product Portal

Open automatic sliding gates for a safe passage

Do you wish to fence off the site with one or more sliding gates? Passing vehicles must be granted as easy access as possible. Loop detectors analyse induction loops installed in the ground and detect an approaching vehicle on time.

Safety for people and vehicles

Assembling safety switch strips on the closing edges assures the safety of man and vehicle. BBC Bircher Smart Access offers activation and safety units that ensure seamless operation of your site fencing.

Sliding door components - BBC Bircher Smart Access
Opening and closing industrial doors safely - BBC Bircher Smart Access

Opening and closing industrial doors safely

Nowadays, everyone using industrial doors, uses technology. This technology can be utilised in many different ways.

Combination with loop detection

By combining radars, sensors, loop detectors and safety switch strips for optimal access control.

Difference between Proloop Lite and Proloop 2

The ProLoop 2 has a number of advantages over the ProLoop Lite. Both loop detectors can be used on ports and barriers, have 6 time functions, 9 sensitivity levels, stand-by current, both have the ASB function and have 4 frequencies.

Loop Detector ProLoop 2

The ProLoop 2 has directional logic and has a protection against power outages. The ProLoop 2 can be simulated thanks to the simulation mode and has 12 integrated error codes and can store and recall 5 of these error codes and also has a reset to the factory settings. The ProLoop 2 is available versions with alarm function. The ProLoop 2 has a supply voltage (240V) of 100-240 VAC and 24 VACDC at 24V. Finally, the ProLoop 2 can easily be connected to an 11-pin connector. The differences are clearly presented in the table.


View detection loop and induction loop in the Product Portal


Proloop loop detection with truck - BBC Bircher Smart Access


The pink line in the graph shows the frequency and inductance variations that are measured by an induction loop when passing a truck. As can be seen in the graph, the induction variation at the cab and the axle of the truck is greater. The induction variation is smaller between the cab and the rear axle.

Lower loop induction

This observation can be explained by the fact that the trailer of the truck is generally higher than the cabin with respect to the ground. The metal of the trailer is further removed from the magnetic field, leading to a lower loop induction. A standard loop detector has a sensitivity of S1, without the adjusted sensitivity of S2.

Graph loop detection - BBC Bircher Smart Access
Graph sensitivity potentiometer Proloop 2 - BBC Bircher Smart Access


In this application, the sensitivity is adjusted via the potentiometer to the value S1. This means that all frequencies higher than this set limit (S1) generate a detection and activate the relay. If we look at the frequency variations generated by the truck when it passes the induction loop, we see that the truck is being detected. If the truck stops on the loop at cab or axle level, the detection is maintained. In case the truck with the trailer stops on the loop, the detection will be lost and the door, barrier or gate will hit the truck.

Increased sensitivity

To avoid the loss of detection, you must increase the sensitivity (S2) (for example 8x). In this way the truck will always be detected, even if the truck stops the trailer on the induction loop. In certain applications, a high sensitivity of the induction loop is not desired or it can cause undesirable detections, for example detection of surrounding objects or interferences between loops. In the aforementioned cases, it is difficult to find the right sensitivity to suit all of the proposed criteria. The ASB (Automatic sensitivity enhancement) then becomes an inevitable necessity.

sensitivity of the detection | Bircher Reglomat

Automatic sensitivity boost (ASB)

During a detection, the sensor automatically multiplies the sensitivity set by the potentiometer (S1) by 8 (S2). The sensitivity is limited to the maximum sensitivity and goes back to the initial value (S1) after each detection. The ASB ensures a high sensitivity during detection to prevent 'loss' of the truck and thus prevent damage and accidents. The ASB function is therefore highly recommended for the detection of elevated vehicles such as trucks, but also for all other all-terrain vehicles that are generally higher off the ground.


View loop detectors from BBC Bircher Smart Access

Loop detectors - BBC Bircher Smart Access

Application example with loop detectors

Read more application examples where loop detectors are applied:

► Parking systems