Abstract: Techniques and mechanisms to mitigate noise in a signal line extending across rails arranged in a split plane configuration. In an embodiment, respective sides of a first rail and a second rail define opposite sides of a boundary region between the rails. The first rail forms a groove and the second rail forms a branch portion that extends at least in part into the groove. In another embodiment, one or more signal lines each extend across the boundary region and proximate to the branch portion, the one or more signals each to communicate a respective signal while the first rail is at a first voltage and while the second rail is at a second voltage. The branch portion and groove contribute to a reduced impedance discontinuity across the boundary region, which mitigates the creation of signal noise in the one or more signal lines.