Laying down the future . . . two engineers install fibre optic cable through the cable highway on AT&T Submarine System's C. S Global Sentinel cable ship. Voice, data and image traffic travel over the cable's fibres at rates of up to five gigabytes a second. Every 75 kilometres, the traffic signals are boosted by optically-amplified repeaters. On an average cable installation journey such as the 7,414-km TAT-10 system, the C. S. Global Sentinel carries 18 to 25 repeaters stored in racks along the ship's cable highway.