Ultra Start 15xx Bedienungsanleitung PDF herunterladen (Seite 82)

TDC Ultra User’s Manual

9-6

Use at Signalized Intersections

This study is speciﬁcally designed for intersections controlled by stop signs,

but it may appear the procedure would work just as well at signalized in-

tersections. To some extent this is true. There are two limitations with this

procedure at signalized intersections:

1. If the queues that build up are very long, it is very difﬁcult to tell

precisely when a vehicle stops, or even see the vehicles at all. The algo-

rithm used to calculate the delays breaks down quickly if the operator

misses a few vehicles.

2. It is not obvious what to do with vehicles that don't experience any

delay at all, i.e. they arrive at the intersection during the green phase.

(All cars stop, to some degree, at Stop Signs.) You can ignore them

completely, but then your total approach volume (which may or not be

important) is wrong; or you can press the Stop and Go keys in sequence

very quickly and say that each of the vehicles experienced a minimum

amount of delay. This tends to distort the average delay per vehicle

calculation in the analysis.

If these limitations do not affect your study, or if the other Delay study in

the TDC Ultra, (which works best on large, busy signalized intersections),

isn't appropriate for some reason, then go for it!

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Ultra Start 15xx Bedienungsanleitung Seite 82