The purpose of this paper is to present long-term measurements in a full-scale study on a basal reinforced piled embankment that make it possible to validate calculations used for the design of the geosynthetic reinforcement (GR). These calculations are normally carried out in two steps. To validate steps 1 and 2 together, it is necessary to measure GR strains. To validate calculation steps 1 and 2 separately, arching A needs to be measured, which is the pressure on the pile cap above the GR. An extensive monitoring project was conducted over a period of four years, in a basal reinforced piled embankment on 17 m of soft clay and peat. This study presents the measured GR strains and load distribution including arching, accompanied by measured groundwater levels and deformations. The subsoil support of the geosynthetic reinforcement disappeared quickly, arching developed over the first three months, and an annual cycle in the load distribution became apparent. Arching effects increase during the summer when conditions are relatively dry, resulting in a larger load on the piles and a reduction in the load on the GR. Additionally, the measured changes after an extremely rainy week are presented.