Count And Occupancy Loops - Siemens UTMC OTU Handbook

6.11.3 Count and Occupancy Loops

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Counter
One Counter function (VC) can be configured for each site. The count bit
changes state each time a certain number of vehicles, determined by the Count
Weighting Factor, have been detected.
The simplest Counter function has a single input configured, which would count
on a single lane (N-counting). Three inputs can be configured for counting the
vehicles on two lanes together (N+1 counting). This arrangement handles
vehicles which straddle both lanes by special placement of the loop detectors
and provides a more accurate count. Also, four inputs can be configured for
counting the vehicles on three lanes.
A count input can be mapped to a UD unit output (see section 6.11.2).
Count Weighting Factor
The Count Weighting Factor is used to define the number of counts required to
cause the reply bit to change state, as shown in the table below. The value
required depends on the maximum vehicle flow rate at each count site. Generally
a weighting factor of approximately twice the maximum flow will be required.
667/HB/31601/000 Page 73
UTMC OTU/MOVA Handbook
Issue 5