Modelling and optimization of constrained alignments for existing railway reconstruction

ABSTRACT

Presently, numerous low-grade existing railways need to be reconstructed to improve their capacity. The core of the supporting analysis process redesigns railway alignments based on existing ones. However, most alignment optimization studies focus on new alignment designs but none have considered the complicated constraints between existing and redesigned alignments. This paper focuses on optimizing constrained alignments for existing railway reconstruction. An optimization model is developed by defining existing alignments into reused and reconstructed sections. The reconstruction cost is formulated as an objective function and three categories of constraints are considered. To solve this model, a two-stage method is developed. Firstly, an automatic segmenting method is proposed for separating existing alignments into the aforementioned two kinds of sections. Then, a multi-directional distance transform is devised to search for redesigned alignments. By being applied to a real-world case, the effectiveness of the proposed method is verified through data and sensitivity analyses.

KEYWORDS:

• Railway design
• existing railway reconstruction
• alignment optimization
• constrained optimization
• distance transform algorithm

Acknowledgments

The authors are grateful to the China Railway Siyuan Survey and Design Group Co. Ltd for supporting them with many real cases.

The corresponding author (Taoran Song) expresses his most sincere thanks to his aunt (Susan Cui) in Richmond, British Columbia for her great and invaluable help in supporting his settlement, research and study at the University of British Columbia, Vancouver.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is partially funded by the National Science Foundation of China (NSFC) with award number 52078497, the Central South University Special Scholarship for Study Abroad.