Identify Optimal Traffic Condition and Speed Limit for Hard Shoulder Running Strategy

Fan Yang,Bin Ran,Fan Wang,Fan Ding,Huachun Tan

doi:10.3390/su13041822

Fan Yang, Bin Ran + Show 3 more

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https://doi.org/10.3390/su13041822

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Journal: Sustainability	Publication Date: Feb 8, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: Southeast University

Abstract

Highway system is experiencing increasing traffic congestion with fast-growing number of vehicles in metropolitan areas. Implementing traffic management strategies such as utilizing the hard shoulder as an extra lane could increase highway capacity without extra construction work. This paper presents a method of determining an optimal traffic condition and speed limit of opening hard shoulder. Firstly, the traffic states are clustered using K-Means, mean shift, agglomerative and spectral clustering methods, and the optimal clustering algorithm is selected using indexes including the silhouette score, Davies-Bouldin Index and Caliski-Harabaz Score. The results suggested that the clustering effect of using K-Means method with three categories is optimal. Then, cellular automata model is used to simulate traffic conditions before and after the hard shoulder running strategy is applied. The parameters of the model, including the probabilities of random deceleration, slow start and lane change, are calibrated using real traffic data. Four indicators including the traffic volume, the average speed, the variance of speed, and the travel time of emergency rescue vehicles during traffic accident obtained using the cellular automata model are used to evaluate various hard shoulder running strategies. By using factor analysis and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) methods, the optimal traffic condition and speed limit of opening hard shoulder could be determined. This method could be applied to highway segments of various number of lanes and different speed limits to optimize the hard shoulder running strategy for highway management.

Highlights

With the development of economy, the highway system become increasingly overloaded with traffic
This section describes the result of applying our methodology to identify the optimal traffic condition and speed limit for hard shoulder running strategy on the research highway segment
When the state of hard shoulders changed, changes of the traffic volume and the average speed are used as benefit attributes, changes of the variance of speed and the travel time of emergency rescue vehicles during traffic accident are used as cost attributes

Summary

Introduction

With the development of economy, the highway system become increasingly overloaded with traffic. The problem of traffic congestion has affected people’s quality of life and caused economic losses. It has been reported that the economic loss of travel time delay and fuel consumption was $121 billion in 2011 worldwide [1,2], and the annual loss was estimated to reach $199 billion in 2020 [3]. Construction of new highways would cost huge funding budget and require long construction period. The growth rate of new highway mileages is far less than the growth rate of traffic volumes. The more effective way to relieve the traffic congestion on highway is to use appropriate transportation management techniques to maximize the operating efficiency of current transportation facilities compared with expanding more highway mileages

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Methods

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Conclusion