JAMAR Technologies TRAX I, Руководство пользователя

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TRAX I User’s Manual
Low Speed Counting (Below 10 mph)
The TRAX I is capable of recording vehicle data as low as idle speeds and
above with a high degree of accuracy. Tube length, tube placement, and the
air switch D-bounce (DT) setting are important factors in achieving excel-
lent results from this type of application. The following guidelines should
be used for low speed volume installations.
Tube Length
The total length should not exceed forty (40) feet. Shorter lengths may
be used provided the vehicle speeds do not exceed 30 mph.
Tube Placement
Tube placement should be perpendicular to the flow of traffic; how-
ever, when using a high DTX setting, a slight angle (by the tube or
angled wheels of a vehicle) will not cause the counter to double count.
Remember, this only applies to low speed counting - tubes should be
placed correctly on the roadway regardless of low or high speed count-
ing. As a reminder, two hits on the road tube represents one count in
the volume mode. Additionally, the TRAX I will record a count even if
the front and rear tires on only one side of the vehicle passes over the
tube, as well as if both front and rear tires do.
Dead Time (DT/DTX)
The DT setting is measured in milliseconds which controls the output
pulse interval from the air switch. Typically, the pulse interval is set at
20 to 40 milliseconds for normal operation. This setting will cover
most speeds; however, speeds from idle to 10 mph will require the DT
setting to be increased. When measuring volume in a very low speed
situation, use a DTX setting of 200 to 300 milliseconds to avoid double
counting.
The above rules may be varied slightly since each tube installation for low
speed traffic counting is unique. The tube length and DT may be adjusted
to fit your specific parameters. Once you have decided on your settings,
monitor incoming data to ensure accuracy.
NOTE: Be sure to reset the DT setting once you have finished your low
speed counting. Using an incorrect DT setting for average speed traffic
will produce incorrect data.
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