A Novel Approach for Operating Speed Continuous Predication Based on Alignment Space Comprehensive Index

Ying Yan,Gengping Li,Zhongyin Guo,Jinjun Tang

doi:10.1155/2017/9862949

Abstract

Operating speed is a critical indicator for road alignment consistency design and safety evaluation. Although extensive studies have been conducted on operating speed prediction, few models can finish practical continuous prediction at each point along alignment on multilane highways. This study proposes a novel method to estimate the operating speed for multilane highways in China from the aspect of the three-dimensional alignment combination. Operating speed data collected in field experiments on 304 different alignment combination sections are detected by means of Global Positioning System. First, the alignment comprehensive index (ACI) is designed and introduced to describe the function accounting for alignment continuity and driving safety. The variables used in ACI include horizontal curve radius, change rate of curvature, deflection angle of curve, grade, and lane width. Second, the influence range of front and rear alignment on speed is determined on the basis of drivers’ fixation range and dynamical properties of vehicles. Furthermore, a prediction model based on exponential relationships between road alignment and speeds is designed to predict the speed of passenger cars and trucks. Finally, three common criteria are utilized to evaluate the effectiveness of the prediction models. The results indicate that the prediction models outperform the other two operating speed models for their higher prediction accuracy.

Highlights

Human-orient and safety supremacy are currently the new guidance during the period of highway construction
Since a number of experimental surveys state that the actual speeds adopted by drivers are considerably higher than those used to determine road design standards [3, 4], several countries recommend the analysis of the design consistency or safety evaluation in order to check excessive differences of operating speed on successive elements along the road [5,6,7]
The main objective of the research in this paper is to propose a continuous operating speed prediction model for passenger cars and trucks on multilane highways

Summary

Introduction

Human-orient and safety supremacy are currently the new guidance during the period of highway construction. The traditional design speed-based alignment design approach usually only specifies the minimum value of one isolated alignment element. This designing method is prone to be inconsistent with successive elements of a road. Since a number of experimental surveys state that the actual speeds adopted by drivers are considerably higher than those used to determine road design standards [3, 4], several countries recommend the analysis of the design consistency or safety evaluation in order to check excessive differences of operating speed on successive elements along the road [5,6,7]. The current version of IHSDM checks the operating speed profile against two consistency criteria. The 85th percentile of the free-flow speed distribution is commonly used to represent operating speed for design consistency evaluation [1, 8]

Methods

Results

Conclusion