Managing traffic requires being able to detect a variety of vehicles characteristics in different circumstances, for different purposes: traffic flows, volumes, speeds and vehicle types for planning and design; detecting incidents for emergency response; flows on ramps for metering; vehicle volumes approaching intersections for signal timing and control; and traffic conditions for traveller information are some examples.
The updated third edition of the FHWA Traffic Detector Handbook published in 2006 a two-volume, comprehensive reference on sensors for traffic management on surface streets, arterials, and freeways. The Handbook provides a comprehensive reference document to aid the practicing traffic engineer or technician in selecting, designing, installing and maintaining traffic sensors for signalised intersections and freeways.
Topics covered include sensor technology, sensor applications, in-roadway sensor design, sensor installation techniques and sensor maintenance.
The sensor technology chapter discusses the operation and uses of inductive loop detectors, magnetic sensors and detectors, video image processors, microwave radar sensors, laser radars, passive infrared and passive acoustic array sensors, and ultrasonic sensors, plus combinations of sensor technologies. One of the more recent types is the wireless magnetometer, a reliable accurate device, which can be quickly and cheaply installed in the roadway.
Sensor application topics include safety, operation, multimodal issues, and physical and economic factors that affect installation and performance.
The appendixes include a variety of research, background papers, and implementation guidance. The information contained in the Handbook is based on the latest research on available treatments and best practices in use by jurisdictions across the United States and elsewhere. References are provided for the student, practitioner, researcher, or decisionmaker who wishes to learn more about a particular subject.
The third edition is published in two volumes: the online version (and PDF download of the Handbook) http://www.fhwa.dot.gov/publications/research/operations/its/06108/
Also see the Vehicle Detector Clearinghouse http://ntl.bts.gov/lib/jpodocs/repts_te/13894.html