In normal cases, the railway track cross-section is laid on ballast at formation level over a blanket layer which rests on the embankment. A strengthening layer of any cohesive material is provided on the side slopes of the embankment. Between the blanket and embankment, there can be an embankment subgrade that would be of a defined thickness and follows the required cross slope.
At places where the formation level is very high because of design requirements that result in a very high embankment. The high embankment is achieved at the site by providing side slope berms of specific widths at regular depth intervals, say around 3 to 6 m. When strengthening layer/layers are provided, those should follow the side slopes with berms.