(excerpt from “A Study of Freeway Traffic Operation” by Charles J. Keese, Charles Pinnell and William R. McCasland, 38th Annual Meeting, Highway Research Board, Washington, D.C., January 5-9, 1959)
Researchers used a variety of elevation towers to obtain the necessary vantage point to film above the traffic stream. This 60-foot portable tower was designed specifically for the photographic data-gathering studies.
In 1956, the Texas Transportation Institute initiated a research project for the Texas Highway Department to correlate freeway operational characteristics with design features.…The study was made principally by the motion picture method, which facilitated the simultaneous evaluation of various operational characteristics and provided the distinct advantage of being able to recreate traffic situations for more thorough study. Traffic operations were recorded on approximately 22,000 feet of 16 mm film during the course of nine separate studies made on freeways in Houston, Dallas and Fort Worth, Texas.
Research was conducted in the following areas: operation and capacity, freeway volume control, lane use and placement, entrance ramps and weaving. A study of freeway median design was also made.…The results of these various studies indicate that the features having the greatest effect on freeway operation are the design and operation of ramps and interchanges. Additional research and development are needed in this area. The volume control, weaving and entrance ramp studies produced some very significant results, which are discussed in the report and will contribute to overall knowledge of freeway operation.
A time-motion study projector was specially constructed for the comprehensive visual analysis of motion pictures, allowing researchers to both replay and stop single frames at a fixed magnification and without warping.
Though time-distance relationships were determined by frame count, the use of clocks on site and in the film provided researchers a check on camera speed and a record of the period of the day.
