Traffic Projection and Assignment (119-3F)

Two traffic assignment packages were developed for use on the Texas Highway Department's IBM 360/50 Computer System. The Texas Small Network Package, which will accommodate small networks of up to 4,000 nodes, implements a new algorithm which allows the trees to be built and the network simultaneously loaded. The Texas Large Network Package, which will accommodate a network of up to about 16,000 nodes, uses a new minimum path algorithm which is considerably more efficient than any previously used. A battery of computer programs for trip distribution was also developed and adopted by the Texas Highway Department.|The accuracy of employment and non-home trip ends from home interviews was investigated. The accuracy of all-or-nothing traffic assignments in estimating turn movements was also investigated.|Home interviews were conducted by the Texas Highway Department in 100 percent of the dwelling units in three adjacent zones in San Antonio. A preliminary analysis of the 100 percent data indicates that very high sampling rates are necessary in order to estimate the number of trips with a small confidence limit.