DTD Automatic Traffic Recorders ATR Inspection and Testing

Installation

Verify that all detection zones have been installed.
Verify that loop sawcuts are finished and level with roadway without excess epoxy.
Verify all equipment is properly grounded.

Lanes

Verify that the detection works properly for each lane that loops are installed.

Piezo Loops

Using a LCR meter, verify that the capacitance is within the tolerances specified by the manufacturer.
Using a LCR meter, verify that the dissipation factor is within the tolerances specified by the manufacturer.
Verify that installed piezo sensors are class II (used to collect axle classification data).
Verify that sensor misses per lane shall not exceed the requirements of DTD during the test period.
Verify that loop continuity must not exceed 1 ohm.
Verify that voltage for a front axle of a car is not less than    80 mV.

Data Retrieval

Verify that real-time vehicle viewing per selected lane can be performed.
Verify that system data retrieval does not impact data collection operation.
Verify that device supports collection of data for opposing lanes of traffic.

Accuracy

Verify that piezos and loops were tested under actual traffic conditions.
Verify that one week of data was collected.
Verify that the volume count is within +/- 10 percent accuracy for the site compared to historical data.
Verify that the vehicle classification type is within +/- 10 percent accuracy for the site compared to historical data.
Verify that sensor misses do not exceed 1 percent in each lane during the test period.

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