At the north end, the approach near Southampton Row was a open cutting with a 1 in 10 (10%) slope. The tracks passed through cast iron tubes underneath the Fleet sewer. They then rose very slightly to enter Holborn tramway station. From here up to Aldwych tramway station the subway was built with a steel roof. Because it was not planned to run a public service south of here at first, the tracks leading towards the Strand were used as a depot with appropriate equipment and inspection pits.