6
Instructions for Locating ‘active’ Loops - from a Moving Vehicle
An audible ‘PING’ sound is emitted when an active in-pavement loop electromagnetic field is detected.
The external probe must be located and secured approximately 50cms from the road surface in a
manner such that there is direct line of sight between the probe and the road surface. A location with
no metal between the vehicle and the road surface will provide the best results. The probe may be hung
from the door and the door closed carefully onto the cable to avoid damage to the cable. The vehicle
must be driven in a manner that enables the probe to pass within the boundary of the in-pavement loop
to provide the best results.
The vehicle should be driven in a safe manner with the drivers attention to the driving function being of
primary importance and therefore it is recommended that the task requires a driver and an ‘observer’.
The vehicle may be driven at speeds between 20kmhr and 100kmhr in accordance with the speed limits
and nominal speed of surrounding vehicles.
** THERE IS NO VISUAL DISPLAY TO DISTRACT THE DRIVER ***
The location where the audible ping is emitted should be noted by the observer.
Instructions for Locating a Loop Winding – Walking on the road surface
! ! ! ! !
W A R N I N G
!!!!!!!
C A U T I O N
! ! ! !
This function requires the operator to walk on the road where the in-pavement loop is
located. This function requires the operator to view the display in order to find the
position of the loop wire within 2 cms positional accuracy. Therefore the operator
must have taken appropriate steps to make the section of road safe where the test is
being performed as it is not possible to observe the instrument AND observe
approaching vehicles simultaneously. This specific nature of this requirement may
vary according to different jurisdictions and local OH&S legislation. The loop location
test should only be undertaken when the operator is in no danger from moving
vehicles on the road surface.
The external probe should be swept over the area where the loop is located. The probe is located
approximately 5-10cms above the road surface.
An audible ‘ping’ will indicate that the probe is
within a loop field and the display will rise as in (a) below and the boxes located at the bottom of the
LCD display will darken / filling in black (c ).
The probe is moved back and forth to confirm the presence of an electromagnetic field. When
attempting to locate a loop winding wire best results are achieved when the probe is drawn from within
the in-pavement loop to outside of the in-pavement loop. The display indicates a HIGH level when a
field is detected. The field is present inside the loop and for a short distance outside the loop. When
the probe is directly on top of the loop winding wire the field is ZERO – this is the position of the
loop winding. This is indicated by the dip (or sustained dip if held in the same position) in (b) below
and the box display (c ) progresses quickly from darken boxes to empty boxes and naturally back to
darken when the probe is moved off the position directly above the loop wire winding.
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(a) ____| Signal goes high when a field is detected
________________ _____________
(b) ____| |_| The signal dips when the probe is directly over the
wire winding
(c )
▒
▒
▒
▒
▒
▒
- Empty rectangular boxes are displayed bottom right of LCD
█
█
█
When a signal level is detected these boxes will darken
