Traffic monitoring by tire noise

Presents the results of work of Planning Systems Inc. performed in fulfilment of the requirements of a Small Business Innovative Research (SBIR) Phase I feasibility study for the Federal Highway Administration (FHWA). The feasibility of developing an acoustic sensing technique to replace the current electro-mechanical (loop detector, tape switch, pneumatic tube) based methods of collecting vehicle axle passages was investigated. We exploit the fact that the dominate source of road noise is the broadband acoustic energy radiated by vehicle tyres by cross-correlating the outputs of spatially separated roadside microphones. The results demonstrate the feasibility of detecting vehicle passages by the cross correlation processing of radiated tire noise. The technique is based on technology developed as a consequence of our work in underwater acoustic signal processing.