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structure can be set up and taken down in approximately 15 minutes, and all of the components
are small enough to be stored in a 6 ft (width) by 10 ft (length) cargo trailer. The approximate
cost of each tower is $2,000, which will vary depending on the price/availability of materials and
the time required for construction. The maximum height of this mounting system is
approximately 39 feet.
The second mounting method evaluated was a sign-mount system. This method provides a
cheaper and simpler method for using the radar sensors. The sign-mount system consists of
poles that are banded to existing sign structures. The approximate cost for this system is $600
each, which will provide a mounting height of approximately 39 feet.
METHODOLOGY
Temporary traffic data collection is difficult to obtain for freeway facilities. Therefore, this study
will focus on a freeway segment. In addition, the case study location has to be a high-traffic
area so sufficient data can be used for the study.
After a suitable location is selected, the sensors will be set up according to their respective user
manuals. Once the sensors have gone through their ‘auto-calibration’ process, fine-tuning will
be done by observing traffic flows and adjusting the detection zones as necessary. Speed data
will be calibrated with hand-held radar, and adjustments will be made to the sensors when
needed.
It is desired to have the sensor’s speed data within 2-3 mph of the hand-held radar. The
measures of effectiveness (MOE) for this study are a comparison of the volume, speed, and
classification data for each sensor. The data for each sensor will be compared to manually
collected data. This comparison will assess the performance of each sensor in a temporary,
remote deployment as an alternative to conventional data collection technologies. Comparisons
will be made on a lane, direction, and total roadway cross-section.
After all three sensors are set up and operating, the Traffic Data Collection System (TDCS) will
be deployed for the manual verification. The TDCS is a video surveillance trailer consisting of a
6 ft (width) by 10 ft (length) cargo trailer which houses a 42 ft telescopic, pneumatic mast. Two
pan-tilt-zoom (PTZ) cameras can be mounted to the top of the mast, and are connected to a
video recording system inside the trailer. The location of the TDCS (200 ft behind the sensors)
will allow for a clear view of the sensors and the passing vehicles.
Each of the radar sensors had different capabilities related to vehicle classification. Therefore,
several vehicle length classes were developed based on research done by various
transportation agencies (as shown in Figure 2). Based on this data, the following four vehicle
classification bins were used:
1. Motorcycles (0 – 10) ft
2. Passenger Cars (0 – 20) ft
3. Single-Unit Trucks (0 – 55) ft
4. Tractor-Trailer Trucks (> 55) ft
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