Test Results - The FHWA/Hughes Test

Test Results - The FHWA/Hughes Test

The FHWA/Hughes Test

The most comprehensive test carried out to date was performed by Hughes Aircraft under the direction of Dr. Lawrence Klein from 1993 to 1994. It was conducted in four locations - Minneapolis, Minnesota in winter, Orlando, Florida in the spring, and Phoenix and Tucson, Arizona in the summer - to allow for various weather conditions to take effect. In each location, there were two installation sites, one on a freeway and one on surface streets, to allow for various parameters and road conditions to exhibit themselves.

In this prolonged test, the accuracy of 21 different detectors of 12 different technologies was compared simultaneously on the same roadway. Volume was the main test parameter, with occupancy and speed tested to a lesser degree. The RTMS was the only traffic sensor to provide detection from both a forward-looking and side-fired mounting. All other traffic sensors were mounted overhead on bridges. The 1995 summary of this test has illuminated the advantages and disadvantages of the various technologies.

The RTMS was the top recommended technology in 5 out of the 8 application categories.

APPLICATION	ASSUMPTIONS	TEST RANKINGS
Signalized intersection control	Detect stopped vehicles Weather not a major factor	True-presence microwave radar Passive infrared Laser radar Ultrasound Video image processor
Signalized intersection control	Detect stopped vehicles Inclement weather	True-presence microwave radar Ultrasound Long wavelength imaging infrared Video image processor
Signalized intersection control	Detection of stopped vehicles not required	True-presence microwave radar Doppler microwave detector Ultrasound Long wavelength imaging infrared Video image processor
Real-time adaptive signal control (e.g., SCOOT)	Desirable for detector footprint to emulate a 6ft x 6ft inductive loop Side mounting capability	Video image processor True-presence microwave radar Passive infrared (with suitable aperture beamwidth)
Vehicle counting (surface street or freeway)	Detect and count vehicles traveling at speeds more than 2-3mph	True-presence microwave radar Doppler microwave detector Passive infrared Laser radar Ultrasound Video image processor
Vehicle speed measurement	Detect and count vehicles traveling at speeds more than 2-3mph	True-presence microwave radar Doppler microwave detector Laser radar Video image processor
Vehicle classification*	By length	Video image processor Laser radar
Vehicle classification	By profile	Laser radar

Source: Detection Technologies for IVHS / Hughes Aircraft Report for U.S. FHWA 1995 DTFH61-91-C-00076 *Note: The RTMS can, as of 1994, classify vehicles by length.

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