关键词: 铁路线路设计, 长大隧道, 坡度折减, 设计规范运用

Abstract: Studying the long tunnel geometric design from its actual operation is the issue should be paid close attention in railway design. Currently, the common approach to determining gradient reduction coefficient of traction is from the Code for Design of Railway Line. This paper analyzes the provisions and experimental expressions about additional aerodynamic drag in tunnel and gradient coefficient in the Code. It emphasizes correct comprehension and flexible application of the Code. The parameter value should be calculated considering the topography, geological conditions, technical standard, investment, and operating conditions of the railway project. The paper concentrates on how to determine the gradient reduced coefficient of traction in long tunnels properly. It also gives some suggestions on the studies of gradient reduced coefficient of traction in long tunnels and the design standard.

Key words: railway geometric design, the long tunnel, gradient reduction coefficient of traction, application of design standard