Complex sentence: Existing evidence on the ground shows that the tramway was of narrow gauge, although it was originally standard gauge (4ft 8 1/2inch (1435.1mm)) the tramway was re-gauged prior to the opening of the public pier.
Split into simpler sentences: Existing evidence on the ground shows that the tramway was of narrow gauge, although it was originally standard gauge (4 ft 8 1/2inch (1435.1mm)). The tramway was re-gauged prior to the opening of the public pier.