Active and passive infrared sensors for vehicular traffic control

Experimental results are presented for both passive and active overhead infrared systems to detect and monitor vehicular road traffic. The active system developed uses lasers and detectors operating in the near infrared spectral range. The passive system uses detectors operating in the thermal infrared region. Both systems make use of computerized signal processing and correlation techniques to determine presence of vehicles, traffic volume, vehicle speed measurement and length classification. Preliminary road tests confirmed the potential of both systems to provide effective, rugged, low cost approaches to vehicular traffic monitoring suitable for use on multilane highways. The comparative advantages of both systems are discussed and their potential for integration in intelligent vehicle highway systems are examined