Traffic Counter Tester II User’s Manual
3-2
Certifying Counters with the TCTII
Once you are familiar with the how the TCTII is setup and operates, you
can begin to use it to certify the accuracy of the counters you are using to
collect data in the field. The tests described in the steps below will enable
you to determine how accurate your equipment is, and whether or not a
counter is in need of service.
Step 1 - Set the Time and Speed
Set the time on the TCTII to 15 minutes by pressing the TAB key until
Set Time is shown on the display, then pressing the DO key until 15
min. is listed. Next, set the speed to the typical speed expected for the
upcoming study, normally between 35 to 55 mph, by pressing the TAB
key until Set Speed is shown on the display, then pressing the DO key
until the speed you want is listed.
Step 2 - Test the Air Switch Sensitivity
To test the sensitivity of the air switch, set the Output dial to 0. Set the
counter you are testing to display each axle hit as it occurs and start a
count. Start the TCTII in A,B mode by pressing DO when A,B is listed
on the display. Slowly turn up the Output dial until the axle hits begin
to register on the counter. Continue to increase the output until the air
switches are recording every pulse. For most air switches, every pulse
should be picked up by the time dial is up to 4 or 5. Record the value
of the dial to track the quality of the air switches over time.
If the output value is high, inspect the nozzles on the counter for an
obstruction. Re-test to see if this has corrected the problem.
Note:
If
a T connector is used to connect the tester to a 4 channel (or larger)
counter, then the required Output setting will be higher.
Step 3 - Test Volume
Reset the Output dial to 10.
Reset the counter being tested for a
volume count and restart the TCTII in A,B mode. The counter and
the TCTII should increment their count at the same rate. After the 15
minutes has ended and the TCTII has stopped, both the counter and the
TCTII should display the same count values.
Next, test the A to B, B to A mode. If your counter does not have the
capabilities for a bi-directional count with a tube spacing of 4.5 inches,
or it has been deemed unnecessary to certify this mode, then proceed
