A system for the collection and processing of traffic flow data by machine methods. Paper presented by the author to the Freeway Operations Committee, Department of Traffic and Operations, Highway Research Board, on January 8, 1962.

A new collection system is presented that has proven to be very practical for conducting accurate traffic surveys and traffic flow research studies. Traffic data is obtained and processed entirely by machines, thereby eliminating human errors. Because the processed data is on punched cards, digital computers may be readily applied to assist in the task of data analysis. Large amounts of traffic data may be obtained and processed at relatively low expense with a minimum of manpower. The basic type of traffic data used in this system consists of vehicle presence and vehicle classification information obtained from ultrasonic vehicle classification detectors. This information is recorded on magnetic tape in the field. These tapes are then processed in a computing center using a special tape readout unit to punch ibm cards directly. A number of computer programs have been written that enable a digital computer to accept these input cards and compute minute averages of the following traffic parameters: passenger car volume, commercial vehicle volume, total volume, lane occupancy, speed, time headway, distance headway, time spacing, and distance spacing.