New Three-Dimensional Highway Design Methodology for Sight Distance Measurement

Abstract

The traditional two-stage highway design process provides separate processing of horizontal and vertical alignments. One drawback of the two-stage methodology, however, is design inconsistency because of drivers' responses that are not detected until the road is built. To remedy this situation, a three-dimensional (3-D) design methodology has been developed to eliminate the need for postchecking to ensure design consistency and availability of adequate sight distance. With the proposed 3-D design methodology, planners and designers can simulate the entire design process at the onset. The paper presents a novel 3-D algorithm for calculating sight distance on the basis of the proposed 3-D design methodology. A case study demonstrates the applicability of the methodology.