High quality vehicle detection is essential to properly operate actuated phases at traffic signals and to facilitate effective management of technician and engineering resources. INDOT operates over 2600 traffic signal controllers, approximately 2000 of which use some form of vehicle detection. The private sector continues to develop innovative sensing technologies that may potentially benefit Indiana motorists and taxpayers by improving system efficiency and lowering installation and maintenance costs. However, the acceptance of new sensing technology requires careful evaluation because to ensure that they provide robust performance 24 hours a day, 365 days a year, with minimal impact on maintenance resources.

This study developed a technical protocol for evaluating vehicle detector performance and applied those techniques to both video detection (in partnership with Texas) and wireless magnetometers. Based on experiences in designing the detector test bed, recommendations are given for stop bar detection zone design using wireless magnetometers. Additional results include a detailed study of the inductive loop detector sensing range for several loop geometries, and an innovative method for interrogating NTCIP-compliant traffic signal systems to allow quality control on signal timing plan implementation. Since this project spanned several years, interim results were documented in the professional literature as they became available. This technical report summarizes those results and provides references to the published papers.

Report Number



magnetometers, loop detectors, inductive loops, vehicle detectors, NTCIP, traffic signals, SPR-3206

SPR Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, Indiana

Date of this Version


3206_technical_summary.pdf (613 kB)
Technical Summary