| description abstract | To better meet the safety requirements and economic benefits of mountainous high-speed railways, long and steep ramps are implemented to overcome elevation obstacles. In this paper, the impacts of speed reduction, operation safety risks, line transportation capacity, maintenance, and operation quality on long and steep ramps are comprehensively considered, and a design method for high-speed railways with long and steep ramps in tough mountainous areas is proposed. This method has also been applied in engineering practice. Considering factors such as the operational organization and quality of electric multiple units (EMUs), it is recommended that there be no restrictions on the ramp sections of EMUs with a design speed of 250 km/h, which makes up 15‰ or less of existing railways in China. The lengths of the ramp sections with slopes of 20‰, 25‰, and 30‰ should not exceed 17, 9, or 6 km, respectively. The ramp section of the EMU running line with a design speed of 350 km/h should be implemented in a way that ensures the relevant explanatory requirements are maintained according to the existing specifications. A practical verification of the comparison and selection of the line schemes of the Junlian to Zhaotong line section of the Chongqing–Kunming high-speed railway shows that the proposed design method can better meet the high-speed railway design needs for long ascending and descending grades in mountainous areas and provide theoretical support for the optimization and selection of line schemes. | |
