A TECHNIQUE TO CALIBRATE CHOICE MODELS

THE NEED FOR FAST, EFFICIENT, AND INEXPENSIVE TECHNIQUES TO CALIBRATE TRANSPORTATION PLANNING CHOICE MODELS LED TO THE DEVELOPMENT OF THE METHODOLOGY DISCUSSED IN THIS PAPER. THE CALIBRATED MODELS CONSIST OF STRATIFIED CURVES WITH A MINIMUM OF THREE VARIABLES TO REFLECT CONDITIONS BOTH AT ENDS OF A TRIP AND ON THE COMPETING TRANSPORTATION SYSTEMS. THE REQUIREMENTS OF A STRATIFIED CURVE MODEL ARE DEALT WITH IN CONSIDERABLE DETAIL AS WELL AS THEIR ADVANTAGES TO THE MODEL-BUILDER AND TRANSPORTATION PLANNER. THE CALIBRATION TECHNIQUE STARTS WITH AN APPROXIMATED SET OF CURVES AND THEN ATTEMPTS, BY RELAXATION OF ONE VARIABLE AT A TIME, TO FIT AN UNKNOWN SET OF CURVES IN A RATIONAL MANNER. THE FIRST ADJUSTMENT OBTAINS THE CORRECT NUMBER OF TRIP PRODUCTIONS INTO THE SYSTEM AS WELL AS THE NUMBER OF ATTRACTIONS OUT OF THE SYSTEM BY TRAFFIC ZONES WITHIN CERTAIN CHARACTERISTIC STRATA. THE CURVES REGULATING TRIP PRODUCTION AND ATTRACTION ARE THEN ADJUSTED TO OBTAIN THE CORRECT TRIP LENGTH OVER THE MODEL SYSTEM VARIABLES. THE FINAL CHECK ON THE TRIPS IS THE ORIGIN-DESTINATION DISTRIBUTION BY SPIDER NETWORK ASSIGNMENTS OR OTHER INDIRECT TECHNIQUES. THIS TECHNIQUE WAS USED IN BALTIMORE, COLUMBUS, AND DETROIT DURING 1969, AND THE MAJOR RESULTS ARE PRESENTED IN FIGURES AND TABLES. THE MODEL AND TECHNIQUE ARE PARTICULARLY SUITABLE FOR COMPUTER APPLICATION TO LARGE STUDIES. /AUTHOR/