Wavetronix SmartSensor HD Manual page 6

SmartSensor HD
when at least 50 cars per lane are counted in the interval.
The RVSD shall detect a minimum separation of 5.5 ft. (1.67 m) between two vehicles depending on vehicle speed and
range.
4.2 Speed Accuracy. Average speed data shall be accurate to within 3 mph (5 kph) for any direction of travel when there
are more than five cars per lane in an interval. Average speed data for any individual lane shall be accurate to within 3 mph
(5 kph) when there are more than five cars per lane in an interval.
The RVSD shall provide per-vehicle speed measurements on 95% of vehicles that are not occluded by other vehicles or by
barriers. The RVSD shall provide per-vehicle speed measurements in which 90% of the measurements are within 5 mph (8
kph).
The RVSD shall measure speed using a dual-radar speed trap that calculates the time delay between two different radar
beams.
The dual-radar time delay method of calculating speed produces accurate per-vehicle speeds which enable accurate length measure-
ments, classification, 85th percentile speed measurements and responsive average speed measurements. In contrast, algorithms that
derive the speed from presence measurements or vehicle durations have been shown to produce significant biases in the speed measure-
ments especially during congestion.
4.3 Occupancy Accuracy. Occupancy data shall be within 10% of truth for any direction of travel on a roadway during
nominal conditions. For example, if the true occupancy in a lane is 20%, then the measured occupancy shall be between
18% and 22%. Individual lane occupancy shall be within 20% during nominal conditions. Nominal conditions exist when
true occupancy is less than 30%, without merging traffic; when average speeds are greater then than 10 mph (16 kph) in
every lane; and when there is less than 20% truck traffic per lane.
4.4 Classification Accuracy. The RVSD shall correctly determine classification for 80% of detected vehicles when the clas-
sification bins are at least 10 ft. (3 m) wide and occupancy of all lanes is below 30%.
5.0 Performance Maintenance. The RVSD shall not require cleaning or adjustment to maintain performance.
The RVSD shall not rely on battery backup to store configuration information, thus eliminating any need for battery replacement.
Once the RVSD is calibrated, it shall not require recalibration to maintain performance unless the roadway configuration changes.
The RVSD shall be manufactured using techniques that will yeild a mean time between failures of 10 years.
6.0 Physical Properties. The RVSD shall not exceed 5 lbs. (2.3 kg) in weight.
The RVSD shall not exceed 14 in. by 12 in. by 4 in. (35.6 cm x 30.5 cm x 10.2 cm) in its physical dimensions.
All external parts of the RVSD shall be ultraviolet-resistant, corrosion-resistant, and protected from fungus growth and moisture
deterioration.
6.1 Enclosure. The RVSD shall be enclosed in a Lexan polycarbonate.
The enclosure shall be classified "f1" outdoor weatherability in accordance with UL 746C.
The RVSD shall be classified as watertight according to the NEMA 250 standard.
The RVSD enclosure shall conform to test criteria set forth in the NEMA 250 standard for type 4X enclosures. Test results
shall be provided for each of the following type 4X criteria:
• External icing (NEMA 250 clause 5.6)
• Hose-down (NEMA 250 clause 5.7)
6 www.wavetronix.com