01657025

Component

Constrained by the available two-dimensional design tools in market, the two-stage method has been traditionally adopted by road engineers for its great convenience. Parameters of horizontal and vertical alignments are considered and determined discretionally, which potentially de-emphasizes the three-dimensional nature of spatial curves. The objective of this research is to focus on the three-dimensional attributes of highway alignments and further explores a safety evaluation method to determine the interrelation between crash rate and spatial curve properties. At first, highway alignment combinations were categorized into 6 classifications, with their respective spatial expressions in mathematical form. Curvature and torsion of spatial curve were algebraically manipulated, and the correlation between geometric design variables and crash rate was finally determined. A few cases encompassing the data of the geometric design and crashes facts were utilized for verification. The results showed that there is a significant positive correlation between curvature/torsion variance and crashes per million vehicles-kilometers, as a slight difference between curvature and torsion could also be spotted. And curvature distribution is found more closely related to crash frequency than torsion spatial variation.

This paper was sponsored by TRB committee AFB10 Standing Committee on Geometric Design.

18-01849

English

18p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; References (24) ; Tables

Crash rates; Highway curves; Highway design; Highway safety; Mathematical methods; Safety management; Spatial analysis

Design; Highways; Safety and Human Factors

Transportation Research Board Annual Meeting 2018 Paper #18-01849

TRIS, TRB, ATRI

Jan 8 2018 10:28AM