The back-to-back geosynthetic reinforced soil with a full-height rigid-facing (GRS-FHR) wall is mostly designed at the bridge approach, at the elevated tunnel entrance, and at the elevated and restricted right-of-way railway line. The stability of the high-speed railway track depends on a stable embankment and subgrade for the smooth function of the line. This article presents the study outcome of lateral deflection of the facing wall and vertical settlement of the backfill of the back-to-back GRS-FHR wall by decreasing the vertical spacing between the opposite wall connecting soil reinforcement under two loading cases. The back-to-back GRS FHR wall was modelled using finite element method-based software and validated with the published reports. Five models with a short length (i.e., 0.35 H) and opposite wall connecting soil reinforcements were used by decreasing the vertical spacing between opposite walls connecting soil reinforcements. The outcome showed that a decrease in vertical spacing improved the vertical settlement of the backfill and the lateral deflection of the facing wall.