Evaluation of vehicle classification equipment; final report

The project was directed to an evaluation of currently available systems capable of doing automatic vehicle classification. A prototype system developed by the United Kingdom's Transport and Road Research Laboratory (TRRL) was also tested. Systems (and appropriate sensing devices) were subjected to basic accuracy tests, tests of internal logic, and 1-2 month (continuous use) field tests at various Interstate sites. All currently marketed systems were found to have serious problems in performing the classifications. Classification systems measuring overall length report numerous errors (discrepancies greater than + or - 5 feet) and systems that counted axles report numerous errors by undercounting. The TRRL prototype unit, however, was found to perform considerably better and was more versatile than other systems. Technical specifications, references, and a proposed classification scheme are also included.