User`s manual

TDC Ultra User’s Manual

8-8

be consistent) press the corresponding 1C-4C key on the TDC Ultra.

Keep pressing the keys as each car crosses the stop bar. Watch the light

and be ready for a light change. When the light turns yellow, press the

YELLOW key. Keep pressing the 1C-4C keys if any vehicles cross the

stop bar after the yellow. Press the RED key when the light turns red.

Again press the 1C-4C keys if any vehicles run the red light.

Now shift mental gears and wait for cars to come to the ﬁrst full stop in

each of the lanes you are monitoring. Press the 1S-4S as each vehicle

arrives at the end of the queue and stops. If it is a very busy intersection,

then the queue could build up for a considerable distance.

Cars often creep up to the end of the queue, and may not actually stop.

You have to use your own judgement to decide when a vehicle has "ef-

fectively" stopped. Just try to be consistent.

Now comes the tough part! While you are watching the end of the queues

and pressing the 1S-4S keys as each car stops, you have to also watch

the light so that you are ready when it turns green. Press the GREEN

key when the light changes. This is the end of one complete cycle of

data collection, and the start of the next.

If there is a large queue build up at the signal, it is very difﬁcult for one

person to accurately catch the start of each green phase, yet this is the

critical point in each cycle. We suggest you have two people doing the

study. One handles the TDC Ultra and monitors the signal phases and

1C-4C keys, the other monitors the vehicles stopping during the red

phase and calls out the lane number as each vehicle stops.

Ending the Study

Continue to collect data until you have all of the data you need. Wait

till the start of a new cycle (after you press GREEN), then turn off the

TDC Ultra.

Remember, the only way to stop a study is to turn the power off.