Input (grade 13): The Kwun Tong Line was extended across the harbor on 5 August 1989 to Quarry Bay Station, which became an interchange station for the Kwun Tong Line and the Island Line.
Output (grade 8): The Kwun Tong Line was extended across the harbor to Quarry Bay, which became an interchange station for the Kwun Tong Line and the Island Line. The extension was launched on 5 August 1989.