Influence of 40.0‰ Maximum Gradient of Metro Main Line on Running Characteristics of Trains

When metro lines cross mountains or rivers, properly increasing the maximum slope standard of the metro main lines will help reduce costs and difficulties of design and construction. In order to study the feasibility of applying the maximum gradient value of 40.0‰ on the metro main line, combined with the vehicle-track system properties of Suzhou Rail Transit Line 8, the influence of the 40.0‰ maximum gradient value on the running characteristics of trains was analyzed from the power of motor car, starting and braking capacity of trains, rescue of failed trains, train running status and dynamic characteristics, and track mechanical characteristics, by using theoretical analysis, train longitudinal dynamics, vehicle-track system dynamics, and finite element method. Results show that the maximum gradient of a metro main line can be 40.0‰ when the B2 type vehicle with 4 motors and 2 trailers is used; when the train passes through the 40.0‰ ramp section, the running safety, stability, starting-braking and fault rescue ability of the train meet the requirements; the maximum stress of the rail is only 37% of the allowable stress, and the maximum longitudinal displacement is only 0.443 mm.