Wavetronix smartsensor advance User Manual page 81

CHAPTER 7 • CHANNELS-ALERTS-ZONES
80
way between vehicles, this can be written as show in Figure 7.23.
Required
Flow Rate
Figure 7.23 – Equation for Dynamic Density Vehicle Count Threshold
Consequently, the Dynamic Density Count Requirement (DDCR) calculated by the Dy-
namic Density filter is computed as shown in Figure 7.24.
Dynamic Density
Count Requirement
(DDCR)
If the number of qualified detections is equal to or greater than the DDCR, then the Dy-
namic Density requirement has been satisfied and the zone output will be activated.
Table 7.1 below reviews the components of the Dynamic Density filter. The number of
qualified detections and their average speed is detected by the sensor. Then based upon
values of Zone Size, % Utilization, Tuning Factor, and headway parameters entered by the
user, the DDCR will be calculated and the zone output determined.
Detected by the Sensor
Entered by the User
Table 7.1 – Description of Dynamic Density Equation
Click in the display area beneath the Dynamic Density label to edit the Dynamic Density
filter (see Figure 7.25).
Ideal
=
Flow Rate
%Utilization x Lane Tuning Factor x Zone Size
= Round
Time Headway x Instantaneous Mean Speed in Zone
Figure 7.24 – Dynamic Density Count Requirement Equation
Component
Qualified Count
Speed
Zone Size
%Utilization
Tuning Factor
Headway
%Utilization
x
=
%Utilization
Time Headway
Description
The number of vehicles that meet a
zone's range, speed and ETA filters.
The average speed of all qualified detec-
tions in the specified zone, as calculated
by the sensor (ft per second).
The length of the specified zone (ft.).
Specified by the user (%).
Specified by the user.
Specified by the user (seconds per ve-
hicle).