The replaceable
toll treadle is made from a
high-performance EDPM extrusion, impervious to attack from
acids, alkalis, salts and ultraviolet.
A single treadle is used
directly for axle counting, enabling simple traffic flow
data to be obtained. It is sensitive to all classes of vehicles,
and the output can be used to give an indication of axle
weight. In conjuction with an inductive-loop presence detector
further information can be deduced, such as the number of
axles per vehicle.
If an inductive-loop detector
is used with a pair of treadles, complete vehicle classification
is possible in free-flowing traffic, and classification
by axle count in slow-moving or decelerating traffic.
Other techniques can be
applied to measure, for example, wheel widths by installing
treadles at an angle to the flow of traffic. In addition,
the output can be used to trigger cameras for enforcement
of speed limits and detection of red-light violations.
Transducer. A pressure-sensitive
co-axial cable, producing an electric charge when compressed
or deformed by impact. Co-axial signal cable is attached,
connections being fully sealed within the treadle.
Housing. The treadle
is carried in an extruded EPDM housing bonded into the road,
simple screw fixings being used to lock the treadle into
the housing. This means that if the treadle becomes damaged
it can be replaced in about five minutes, by an unskilled
operator. This feature will minimize lane closures traffic
delays and potential revenue loss.
Interface. The
treadle interface is designed to ensure reliable detection
and accurate counting of every vehicle axle at any speed,
including zero.
Specifications
Minimum Life:
25 million operations
Housing Dimensions:
Section
size:
50mm (w) x 40mm (d)
Treadle lengths:
1, 2, 2.5, 2.75, 3, 3.25, 3.5, 4, 4.5, 5m
Signal cable length:
10mm (Other lengths to order)
Piezo-electric cable
specifications
Piezo-electric
coefficient: 25pC/n at 23oC
Temperature coefficient:
0.5% per oC
Capacitance:
750 pF/m
Insulation resistance:
>1010 ohm
Temperature range:
-40 to +70oC
|
