Study of Alternative Interchange Horizontal Alignments Optimizing Model Based on Genetic Algorithm

Abstract

It is known that the work of highway geometric design is very complicated and needs significant calculation. In highway geometric design, the horizontal alignment design of an alternative interchange system is the most difficult step. Artificial design cannot fully meet the various provisions, so there is a need for good design, and the optimal design model of ramp horizontal alignments and an efficient method for reducing design cost and geometric design automation have become particularly important. Based on the genetic algorithm (GA), this research proposes an optimizing model with the trait of searching widely so as to satisfy all constraints in the horizontal alignment design of an alternative interchange. First, by analyzing the basic elements of the ramp horizontal alignment and accumulating the regularity of the basic elements between inflection points, four new ramp element types are defined according to the variation of the curvature radius along the horizontal alignment. Then, after defining the components of the GA, a basic model for solving ramp horizontal alignments is developed. Testing results suggest that the optimal model can determine horizontal layouts of alternative interchanges correctly and efficiently.