Cause Analysis and Rectification Measures of Chongqing Rail Transit Line 1 Low-frequency Train Oscillation

Abstract

Objective To address the issue of low-frequency train oscillation on Chongqing Rail Transit Line 1 (hereinafter as ′Line 1′), it is necessary to analyze the causes of the oscillation and formulate appropriate rectification measures. Method The causes of low-frequency train oscillation on Line 1 are analyzed by examining oscillation characteristics, track geometry, bridge vibration, and rail profile changes, rail grinding measures are formulated. The causes of periodic rail wear from both track and vehicle perspectives are explored, and measures to address train oscillation caused by periodic rail wear are proposed. Result & Conclusion The causes of low-frequency train oscillation on Line 1 include: track geometry irregularities and bridge vibrations that do not directly cause abnormal vehicle oscillation; since the rail profile exhibiting periodic changes with a wavelength of approximately 12 meters, at higher train speeds and under rail profile periodic variation action, the lateral natural mode with a vehicle frequency of 2 Hz will be activated, leading to severe carbody oscillation. Through the rail grinding plan, the vehicle operation stability index after grinding decreases by about 0.5 compared to before grinding, with all the stability indices within the grinding section remaining below the limit of 2.5, thus alleviating the oscillation problem. The significant track geometry irregularities and the vehicle poor disturbance-resistant performance are identified as causes of periodic rail wear. The combination of rail milling and track fine adjustment measures can completely resolve the train oscillation issue caused by periodic rail wear.

Keywords

• urban rail transit
• low-frequency train oscillation
• train oscillation cause
• rectification measure