Research on Seamless Small-Radius Curved Track for Subway Upper Cover Property Depot External Lines

[Objective] To reduce vibration and noise impacts from depot train operation on the upper cover property, it is necessary to study the seamless design scheme for small-radius curved tracks on subway upper cover property depot external lines. [Method] The necessity of seamless design for depot external lines is introduced; the key parameters of small radius curved CWR（continuously welded rail） on depot external lines are analyzed. Based on CWR inspection verification principles, CWR inspection verification and optimization designs are conducted for external line curved section with a radius of 150 m. [Result & Conclusion] When 1 667 pieces of new type Ⅲ bridge sleepers per km are laid in the 150 m radius curved section of depot external lines, and the No. 7 CWR elastic bendable rail turnout is also laid, CWR laying requirements could be met. The optimal CWR design scheme for depot external lines is: adopting new type Ⅲ bridge sleepers for depot external lines, filling the gap spacing less than 5m between two lines with ballast, widening shoulder width of the outer curve track bed to 400mm, setting elevated ballast shoulders, and setting ballast embankment slope ratio to 1∶1.75. The proposed optimization scheme can enhance CWR stability and safety margin.