Dual Loop Detector LD0l
User Manual
with the longest sides at right angle to the direction of traffic movement. These sides should ideally be 1 metre
apart. The length of the loop will be determined by the width of the roadway to be monitored. The loop
should reach to within 300mm of each edge of the roadway.
In general, loops having a circumference measurement in excess of 1O metres should be installed using two
turns of wire, while loops of less than 1O metres in circumference, should have three turns or more. Loops
having a circumference measurement less than 6 metres should have four turns. lt is good practice at time of
installation to construct adjacent loops with alternate three and four turn windings.
5.4
Loop lnstallation
AII permanent loop installations should be installed in the roadway by cutting slots with a masonary cutting
disc or similar devise. A 45ºcrosscut should be made across the loop corners to reduce the chance of damage
that can be caused to the loop at right angle corners.
NOMINAL SLOTWIDTH: 4mm
NOMINAL SLOT DEPTH : 30mm TO 50mm
A slot must also be cut from the loop circumference at one comer of the loop to the roadway edge to
accommodate the feeder.
A continuous loop and feeder is obtained by leaving a tail long enough to reach the detector before inserting
the cable into the loop slot. Once the required number of turns of wire are wound into the slot around the
loop circumference, the wire is routed again via the feeder slot to the roadway edge.
A similar length is allowed to reach the detector and these two free ends are twisted together to ensure they
remain in close proximity to one another. ( minimum 20 turns per metre ) Maximum recommended feeder
length is 100 metres. lt should be noted that the loop sensitivity decreases as the feeder length increases, so
ideally thefeeder cable should be kept as short as possible.
The loops are sealed using a "quick-set" black epoxy compound or hot bitumen mastic to blend with the
roadway surface.
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