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Compared to manual counts on the same day, total volume inaccuracies of SmartSensor 105
using the tripod and sign-mount sytems were 2% and 13%, respectively. The accuracy of the
sign-mounted SmartSensor HD was better than the SmartSensor 105, but slightly less acurate
than the tripod-based SmartSensor HD. When compared to the manual volumes, total volume
inaccuracies of SmartSensor HD using the tripod and sign-mount sytems were 0% and 2%,
respectively.
The discrepancies between the two mounting systems could be attributed to the mounting
support. Since the sign post was the same offset at the tripod-bases, the mounting height of the
sensors remained the same. However, the height of the sign post was lower than the guy-wires
on the tripod bases, so there was slightly less stability for the sensors and an increased
possibility for sensor movement. Depending on the sign location and required height of the
sensor, this lack of support may not be an issue in all cases.
SUMMARY
This study evaluated three different radar-based sensors to determine their accuracy in
collecting vehicle volume, speed, and classification data. It also evaluated two types of sensor
mounting configurations to determine if they have a significant influence on sensor accuracy. In
addition, set up guides for the SmartSensor 105, SmartSensor HD, and RTMS are provided in
the appendices.
For the volume comparison, the SmartSensor HD showed a consistently higher accuracy over
the SmartSensor 105 and RTMS, except for the test when the sensor malfunctioned. The
SmartSensor HD had lane volume accuracies greater than 95%, directional volume accuracy of
at least 97%, and a minimum total volume accuracy of 98%. The accuracy of the SmartSensor
105 was within 69% for lane volumes, 81% for directional volumes, and 87% for total volumes.
The RTMS accuracy was within 74% for lane volumes, 97% for directional volumes, and 99%
for total volumes. The volume data from the ATR was also used in the comparison and
produced similar results as the SmartSensor HD (within 96% for lane volumes, 99% for
directional volumes, and 99% for total volumes).
Speed data compared during this study showed similar readings for both the SmartSensor 105
and SmartSensor HD, and significantly lower speed readings from the RTMS (except for one
lane). Although the speed calibration for the SmartSensor 105 was a tedious process, the
resulting speeds were relatively close to the manually recorded speeds (within 3-4 mph). The
SmartSensor HD did not require any type of speed calibration, and it consistently showed
speeds similar to the hand-held radar (within 2-3 mph). The speed calibration process for the
RTMS was easier than that of the SmartSensor 105, but the data was still inaccurate after
calibration and showed differences of up to 20 mph in some instances.
Vehicle classification seemed to be the most difficult task overall for all of the radar sensors.
Based on the data collected, the SmartSensor HD was the most accurate in classifying vehicles
and had accuracy ranges of (-2% to -4% for small vehicles, 11% to 115% for medium vehicles,
-7% to 67% for large vehicles), followed by the RTMS (-25% to 11% for small vehicles, -23% to
407% for medium vehicles, and -63% to 200% for large vehicles), and the SmartSensor 105
(-72% to -41% for small vehicles, 353% to 1761% for medium vehicles, and 4% to 260% for
large vehicles). In addition, the data from the ATR also showed some discrepancies when
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