There would have been two separate tracks, each electrified on the 25 kV AC system. In the deep tunnel section separate bores were to be tunnelled for each track. The track was to consist of continuous welded rails on concrete foundations - 'slab track'. The tunnel was to be controlled by British Rail's standard three-aspect colour light signals together with their automatic warning system (AWS). This would have permitted train frequencies of 90 seconds, although initial proposals envisaged a 2.5 minute headway.