CHAPTER 7 CHANNELS-ALERTS-ZONES 79
lters. e SmartSensor Advance provides two very powerful detection qualication lters:
Qualied Count and Dynamic Density™. ese lters are mutually exclusive (only one
may be active at a time).
e qualied count lter is used to limit a zone’s outputs to times when there are a certain
number of qualied detections in the zone at one time.
Click in the Qualied Count range and the Edit Qualied Count lter will appear. Edit
the min and max values to set the qualied count range (see Figure 7.20). Only qualied
detections within the set range will activate zone outputs. e minimum qualied count
value is 1 and the maximum qualied count value is 25.
Figure 7.20 – Qualified Count Filter
Click the radio button to the left of the Qualied Count label to enable the qualied count
lter.
Dynamic Density
Dynamic Density is a type of vehicle platoon detection that activates a zone’s output when
the number of qualied detections within a zone equals or exceeds a density requirement.
e following equations explain the density requirement formula, called the Dynamic
Density Count Requirement (DDCR).
First, trac density is dened as the number of vehicles within a zone, divided by the area
of the zone (see Figure 7.21).
Density =
Number of Vehicles in a Zone
Zone Size (ft.) x Lane Tuning Factor
Figure 7.21 – Required Density Equation
To maintain a given level of eciency, the required density increases as speeds decrease;
similarly, the required density decreases as speeds increase. erefore, to achieve a Required
Flow Rate, the density of trac will dynamically change with the speed of the vehicles as
shown in Figure 7.22.
Density =
Required Flow Rate
Speed
Figure 7.22 – Flow Rate Equation
In addition, the Required Flow Rate is equal to the ideal ow rate multiplied by the re-
quired % Utilization. Since ideal ow rate is inversely proportional to the ideal time Head-
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