Original civil engineering features of the railway will be retained wherever practicable. All cuttings and embankments will be assessed for cultural and engineering significance, aesthetic values and need for disturbance.

Criteria for disturbance will include such factors as safe operation of the railway, reinstatement of original alignment and grade, and potential of the features to slip or subside. In some cases vegetation may be a key factor to the stability of a feature, in others it may be contributing to its instability. Vegetation may also be masking key engineering features along the line, such as the stone-faced embankment upstream of the Ladle Bend bridge.

Construction sites will be located away from the heritage formation, as will borrow-pits, should any be required for providing fill to reinstate formation.

New works will be distinguished from the old – which will especially apply to the Maymorn connection route and Kaitoke deviation.