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| The FHWA/MnDOT Guidestar/SRF Test |
| This test was conducted over a two-year
period from 1995-1996 in Minneapolis, MN by the Minnesota Department
of Transportation. Testing was performed by the SRF Consulting
Group and had somewhat different objectives than the Hughes Test.
The test compared the performance of 17 detectors of 8 technologies.
Besides accuracy, it looked at effects of weather, reliability and
the difficulty of setup and maintenance.
However, the single location could not reveal some of the problems
that the Hughes test did. Nevertheless, its long-term observation
of detectors' behaviour in the same location under various weather
conditions revealed essential problems in some traffic detection
technologies, such as accuracy drifts caused by large temperature
changes (e.g. summer to winter).
One finding suggested that salt spray from cars degraded the performance
of video and optic-dependent devices. |
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| The final report provided a definition of the ideal
device. Such a device would be capable of measuring in multiple lanes,
be capable of overhead or sidefired mounting, have a serial communication
link for remote adjustments, offer additional measurements besides
volume, work well in all types of weather, and offer realtime information
for ITS projects. For temporary counting stations, a device should
be able to be battery or solar-powered, and be quickly deployed
and installed. |
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Among its conclusions, the final report
said:
Radar and video devices have the advantage of multiple-lane
detection from a single unit.
The technologies with the potential to meet the majority of the test
objectives were: Radar, Passive Infrared, Doppler Microwave and Pulse
Ultrasonic. The RTMS radar detector is the only one to be
included in all recommendations. |
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