USE OF GRAVITY MODEL FOR DESCRIBING URBAN TRAVEL: AN ANALYSIS AND CRITIQUE

Abstract

THIS RESEARCH PROVIDES EVALUATIONS OF THE GRAVITY MODEL AS AN ANALYTICAL TOOL FOR SIMULATING PRESENT AND FORECASTING FUTURE URBAN TRIP DISTRIBUTION PATTERNS. THE EVALUATIONS WERE MADE BY COMPARING GRAVITY MODEL TRIP INTERCHANGES WITH THOSE FOUND IN HOME INTERVIEW ORIGIN AND DESTINATION SURVEYS CONDUCTED IN WASHINGTON, D. C., IN 1948 AND 1955. THE 1955 SURVEY DATA WERE USED FOR CALIBRATING THE BASIC GRAVITY MODEL AND FOR TESTING THIS MODEL FOR ITS ABILITY TO SIMULATE CURRENT TRAVEL PATTERNS. THE 1948 SURVEY PROVIDED COMPREHENSIVE DATA TO ANALYZE THE FORECASTS MADE BY THE CALIBRATED MODEL. THE GRAVITY MODEL WILL GIVE SATISFACTORY RESULTS IF PROPERLY CALIBRATED AND TESTED. THE LEVEL OF ACCURACY OBTAINED BY FORECASTING TRIP DISTRIBUTION PATTERNS IN 1948 WAS COMPARABLE TO THE LEVEL OF MODEL ACCURACY FOR THE BASE YEAR. /AUTHOR/