This paper was written concerning a test section with geogrid-reinforced railway ballast based on field tests. I aim to introduce the variation of the alignment track geometry parameter taking into consideration the geogrid reinforcement. The main advantage of the ballast reinforcement with geosynthetic inclusions is the reduction of the longitudinal level faults and the deterioration speed. I observed the alignment (i.e., the horizontal geometry) changes. The duration of the field test is approximately 11.5 years. Five different geogrid types were incorporated below the ballast bed on the Kelenföld-Hegyeshalom state board (No. 1) railway line in Hungary in 2010. The test section is only straight for 700 m in length (with reference sections with the same geometry and structural set-up), i.e., the horizontal geometry of the track does not influence the results. A statistical analysis was executed to compare the behavior of the sections, based on both the geogrid-reinforced sections and reference sections. As a result of the investigation, it can be concluded that there were some geogrid types, which seemed to be adequate to decrease the deterioration speed of the alignment parameter of the ballasted railway track. A very high variance (standard deviation) was observed in the results, this is because they cannot be determined as a general horizontal railway track stabilizing solution.