DIRECT EVALUATION OF GEOMETRIC HIGHWAY DESIGN

THIS PAPER IS PART OF A COMPREHENSIVE STUDY ON THE FEASIBILITY OF EVALUATING GEOMETRIC HIGHWAY DESIGN CONDUCTED BY THE JOINT HIGHWAY RESEARCH PROJECT AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY. THE NATURE OF GEOMETRIC DESIGN, AND ITS INFLUENCE UPON THE DRIVER AND TRAFFIC BEHAVIOR, ARE OUTLINED AND IT IS SHOWN HOW DRIVER BEHAVIOR CAN BE USED FOR EVALUATION. "DIRECT EVALUATION" WAS FOUND TO BE A SIMPLE AND RELIABLE METHOD FOR EVALUATING GEOMETRIC HIGHWAY DESIGN FEATURES. AN EXPERIENCED DESIGNER COMPARES ACTUAL TRAFFIC PATTERNS WITH THOSE DESIRED AND EXPECTED BY THE DESIGNER OF THE ROAD. THE DIFFERENCE BETWEEN DESIRED AND ACTUAL TRAFFIC PATTERNS SERVES AS A VERY VALID BASIS FOR EVALUATION. UNIFORMITY FOR SEVERAL OBSERVERS AND LOCATIONS IS ASSURED THROUGH STANDARD PROCEDURES AND EVALUATION FORMS FOR EACH SITE. THE FEASIBILITY OF THIS METHOD OF EVALUATION IS DEMONSTRATED. DIRECT EVALUATION AND CONVENTIONAL METHODS FOR EVALUATION ARE APPLIED TO A SERIES OF ACCELERATION LANES OF SEVERAL DESIGN PERIODS. THE RESULTS ARE COMPARED FIRST FOR EACH ACCELERATION LANE, SHOWING THE VARIATIONS BETWEEN EVALUATION METHODS; THEN FOR THE DIFFERENT ACCELERATION LANES, DEMONSTRATING THE NEED FOR DESIGN IMPROVEMENTS AND COORDINATING EVALUATION RESULTS WITH ACTUAL CHANGES IN TRAFFIC PATTERNS. /AUTHOR/