New Algorithm for Calculating 3D Available Sight Distance

Abstract

The importance of considering three-dimensional (3D) sight distance in geometric design has been demonstrated by several researchers. However, little progress has been made in the use of 3D analysis in the design of highways. This can be mainly attributed to the complexity of the computations required for 3D analysis. This paper presents a new algorithm for calculating the 3D sight distance. The algorithm is considered more efficient, less computationally intensive, and more flexible than previously developed approaches. The algorithm is based on a parametric representation of the roadway and roadside features without any implicit approximation of the roadway surface. The paper presents analysis results of various alignment configurations to demonstrate the use of the algorithm and to examine the influence of different geometric elements on the 3D sight distance. The paper also provides an analytical tool that can investigate and determine the conditions under which a 3D analysis is considered necessary.