Manual
VEK S4
FEIG ELECTRONIC GmbH
03/09
5
1.1 Vehicle
detection
It is established using an LC oscillator whether a metallic vehicle is in the loop area. The output of the
channel is switched depending on the selected output function.
Loop head gap and loop length are freely selectable and adjustable (see 6 Technical data ). The optimum
loop position must be determined with appropriate measuring methods for laying the loops over reinforced
roadbeds. The laying recommendations must be observed. It is recommended to use the widespread loop
geometry according to TLS II.
1.2 Compensation
A calibration is performed each time the detector is powered up or by pressing the button for longer than 1 s.
After a power interruption, automatic calibration is performed only if the supply voltage was absent for at
least 0.5 s. The calibration time is approx. 1 s if during this time no vehicles have passed through the loop.
Longer calibration times are caused by frequency instabilities; their causes must be determined and
remedied.
1.3 Classification of vehicles
The VEK S4 detector has two classification modules for the vehicle recording. These can be parameterised
independently from each other.
1.3.1 Vehicle
data
The typical frequency change for vehicles and its time course on two induction loops with known geometric
dimensions are used for deriving the following factors:
•
vehicle
class
•
vehicle
speed
•
vehicle
length
•
net time gap between the vehicles
•
occupied time of the loops
•
travel
direction
The vehicles are classified in 8+1 classes according to TLS guidelines 2002:
•
car
•
car with trailer
•
truck
•
truck with trailer
•
van
•
bus
•
motorcycle
•
articulated
vehicle
•
non-classifiable vehicles, e.g. lane changers
1.3.2
Traffic Jam Detection
The detector signals a traffic jam if the traffic is flowing too slowly <10km/h. In this state, a dummy vehicle
with (Other, l = 4.0 m, v = 5 km/h) is reported. Every individual vehicle is also recognised and reported for
traffic queues if the gap between the vehicles enables both loops. The jam signal will be reset when both
loops become free.
Note: A correct detection of driving direction is not guaranteed for all traffic jam situations.
1.3.3
Recording in the case of loop fault
Speed and length measurement and classification is not possible in the case of a defective loop. A dummy
vehicle (Other, l = 4.0 m, v = 0 km/h) is reported for every vehicle which crosses the intact loop in the case of
loop malfunction.
Note: A loop fault is not reported if one or both loops have been intentionally deactivated as the classification
module concerned in this case is completely switched off.
