In　bilayer　graphene,　the　application　of　a　perpendicular　electric　field　breaks　the　inversion　symmetry　to　open　a　bulk　band　gap　to　harbor　the　quantum　valley　Hall　effect.　When　the　field　varies　spatially,　a　topologically　confined　mode　(also　named　the　zero-line　mode)　arises　along　the　zero-field　line.　In　this　work,　we　theoretically　investigate　the　electronic　transport　properties　of　the　multichannel　zero-line　systems.　The　finite-size　effect　in　topological　systems　(e.g.,　quantum　Hall　effect,　topological　insulators)　often　induces　a　topologically　trivial　gap　to　realize　a　normal　insulator.　To　our　surprise,　we　find　that　the　coupling　between　neighboring　zero　lines　can　give　rise　to　striking　electronic　properties　depending　on　the　number　of　channels　m,　i.e.,　a　trivial　band　gap　for　even　m,　whereas　a　nontrivial　gapless　mode　for　odd　m.　We　further　show　that　these　findings　apply　to　various　ribbon　orientations.　A　general　effective　model　is　constructed　to　provide　a　clear　physical　picture　of　the　emergence　of　gapless　modes.　In　the　end,　a　gate-tunable　device　is　proposed　to　function　as　a　switch　with　controllable　current　partitions.　We　believe　that　our　findings　are　experimentally　accessible,　and　have　potential　practical　applications　in　designing　multifunctional　valley-based　electronics.