Coordination Design Evaluation of Expressway Alignment Based on Spatial Geometric Properties

Abstract:

To effectively evaluate and guide the coordination design of expressway alignment， this paper proposes an evaluation model based on alignment geometric parameter fitting， which uses driving simulation and real vehicle test to obtain vehicle operation data. The index selection and optimization measures are presented afterward. First， the indexes that give priority to coordination design are selected and the curvature k and torsion τ are proposed as the spatial characteristic parameters of alignment. Then， a binary polynomial evaluation model is established to evaluate the design coordination of alignment flexibility and curvature difference Δk and torsion difference Δτ by multivariate nonlinear fitting in combination with driving simulation experiment and real vehicle test. After that， the model is modified by adjusting the cross section and safety facilities. The results show that the evaluation model can better reflect the relationship between alignment index， cross-sectional information， traffic safety facilities， and vehicle operation estate. Furthermore， it provides guidance for the design and application of expressway alignment coordination. Finally， the basis of index selection and optimization measures are presented by deducing the value range of Δk and Δτ.

Key words:expressway;coordination design;spatial geometric properties;curvature difference;torsion difference;multivariate nonlinear fitting