A UTILITARIAN THEORY OF TRAVEL MODE CHOICE

INTENSIFIED STUDY OF PUBLIC TRANSIT SERVICE HAS PLACED DEMANDS ON THE TRANSPORTATION PLANNER FOR IMPROVED CHOICE OF TRAVEL MODE MODELING TECHNIQUES. AN UNDERLYING OF MODAL CHOICE IS NEEDED TO CORRECT INADEQUACIES IN OUR PRESENT APPROACH. A THEORY IS PROPOSED THAT IS BUILT ON THE SUPPOSITIONS THAT INDIVIDUAL CHOICE OF MODE IS UTILITARIAN, THAT COMMON MEASURES OF INDIVIDUAL TRIP UTILITY ARE SUBJECT TO CHANCE ERRORS DESCRIBABLE BY THE NORMAL DISTRIBUTION ERROR FUNCTION, AND THAT DEVIATIONS RESULT FROM PREDICTABLE INFLUENCES. A DIFFERENCE IN DISUTILITY MEASURE IS SET FORTH FOR COMPARISON OF TRAVEL UTILITY. THE MEASURE COMBINES TIME, CONVENIENCE, AND DOLLAR COST INTO A COMMON UNIT OF EQUIVALENT TIME. THE PROBABILITY OF FREE CHOICE OF A GIVEN MODE IS DESCRIBED MATHEMATICALLY AS A FUNCTION OF THE POSSIBLE DISUTILITY SAVINGS. THE FORMULATION IS POSTULATED TO BE THE NORMAL PROBABILITY DENSITY FUNCTION, PREDICTING 50 PERCENT PROBABILITY AT ZERO DISUTILITY DIFFERENCE. SUBMODAL-SPLIT STUDY RESULTS PERTAINING TO BOTH TRANSIT AND HIGHWAY ROUTE CHOICE ARE EXAMINED AND FOUND TO SUPPORT THE FREE MODAL CHOICE MATHEMATICAL DESCRIPTION. DEVIATIONS TO BE EXPECTED IN APPLYING THE THEORY TO CHOICE OF PRIME MODE ARE EXAMINED. IT IS ASSUMED THAT LONG TERM CAPTIVITY TO TRANSIT OR AUTO CAN BE EXPRESSED AS A CONSTANT PROBABILITY, AND THE RESULTANT CONSTRAINED FORMULATIONS ARE ILLUSTRATED. EFFECTS OF EXCESSIVE TRIP LENGTH AND DESIRABLE OPERATIONAL REFINEMENTS ARE DISCUSSED. IT IS CONCLUDED THAT THE PROPOSED THEORY IS READILY APPLICABLE TO MODALCHOICE FORECASTING AND MULTIMODE ANALYSIS AND MAY LEAD ALSO TO BROADER APPLICATIONS. /AUTHOR/ BROADER APPLICATIONS /AUTHOR/