TRIM SLOPES

Hello.

I want to trim the right runner with the left one:

as crop reference I select the left corridor:

but I don't get the expected result (green):

how can it be solved? Thank you!

(attached 2 runners)CC_OBL_TRF_Via1_Alineacio.dgnCC_OBL_TRF_Via1_Balasto.dgnCC_OBL_TRF_Via2_Balasto.dgn