“…Continuous models have been also developed for important travel characteristics such as travel flow densities and intensities (i.e., vehicle-miles travelled per unit area), the number of route crossings and average distance travelled for various routing systems and origin-destination distributions (e.g., Smeed, 1961Smeed, , 1963Smeed, , 1971Smeed, and 1977Fairthorne, 1965;Holroyd, 1966 andHolroyd and Miller, 1966;Wilkins, 1969;Vaughan, 1971Vaughan, , 1972Vaughan, , 1974Vaughan, , 1976Vaughan, , 1977Vaughan, and 1979. Schneider (1967) presents a different approach for direct estimation of travel flow density at a point.…”