Analysis of Escape Risk and Braking Strategy for Commuter Trains under Rescue Treatment
In view of the lack of research on rescue scenarios in the operation of metro railway and the inability of the electric multiple unit(EMU)to fully meet the timeliness requirements of rescue,the runaway risk and braking strategy of metro train rescue conditions are studied.Firstly,a longitudinal dynamic model is established for the coupling of multi formation trains and then Beijing New Airport Line is token as an example to analyze the potential risk of train slip caused by the existing urban rail transit operation under rescue scenario.Finally,based on relevant standards,this study analyzes the comfort of passengers under different braking modes during the rescue process.The results show that when coupled at a speed of 5 km/h on a 33％o slope,the acceleration and jerk rate of the train will reach 10.5 m/s2 and 9.9 m/s3 while at holding brake mode,and slip will occur.However,the acceleration and jerk rate of the train at emergency braking mode decrease by 63.1％and 54.7％,respectively,and no slip occurrs.When the coupling speed is reduced to 3 km/h,the maximum acceleration and maximum impact rate are reduced to 2.1 m/s2 and 2.4 m/s3,respectively,which means passenger comfort significantly improves.When the train is parked on a slope,due to the brake-traction switching process,the holding brake force should reach to 60％or more of the maximum service braking force to ensure that the vehicle will not slide on the maximum slope.
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