The Bass Strait 1 (BS-1), which was laid in 1995, is an 18 fibre cable, providing a repeaterless link from Sandy Point exchange, Victoria with Boat Harbour Exchange, Tasmania, a distance of 245 kms.

Initially, this route will be operated with a transmission bit rate of 622 Mbitls. Of the total 18 fibres in the cable, only 6 fibres will be used initially (4 to carry traffic and 2 as stand-by) while the remaining fibres will be kept as spares for future growth requirements.

The submarine cable is jointed to the exchange entry cable in manholes located on the beaches at both Sandy Point and Boat Harbour. The distance for the submarine portion between beach manholes is approximately 240 kms. The Sandy Point and Boat Harbour exchanges are approximately 1 km and 4 kms respectively from the high water mark.

Siemens SDH transmission equipment is employed for the link along with an integrated network management system. A transmission upgrade to 2.5 Gbits/s is envisaged towards the end of this decade.

The submarine cable, supplied by Aleatel TCC, is a lightweight, screened, submarine, cable design with single or double wire armouring.

Lightweight screened land cable is used un the ducted sections from exchange to beach manhole. Double Armoured submarine cable has been used for the beach/littoral zones and undersea sections of high risk. Single Armoured submarine cable has been used for the remaining low risk sections (i.e., the majority of the route) below Bass Strait.

From Sandy Point exchange, the land cable, a lightweight, screened cable (also supplied by Alcatel TCC) has been installed in ducts to the beach manhole, using standard hauling techniques. Ducting from this manhole extends to the beach, under the sand dunes. Directional boring techniques were used to install this ducting under the environmentally sensitive sand dune area. This section of ducting, extending into the beach, is sealed to prevent ingress of sand/silt, thus allowing ready replacement of damaged cable if necessary. Double wire armoured cable has been installed in this section of conduit (beach manhole to beach and beyond) by hauling from the cable laying vessel, into a pre-prepared 2 metre deep trench at the beach and subsequently through the conduit to the manhole. Buried deadman anchors are employed at the conduit end to hold this cable in position. Articulated pipe is fitted to the cable from the conduit end out into Bass Strait for a distance of 350 metres from Sandy Point.

From Sandy Point, the double armoured cable extends into Bass Strait for 15 kilometres. At this distance, it converts to single armoured design. A short length (1 kilometre) of double armoured cable design is employed 45 kilometres from the beach manhole to protect the cable from rock projections on the sea floor. From this short double armoured section, the cable continues as single armoured cable for approximately 184km before reverting back to double armoured design for the final installation to the beach manhole.

The cable route into Boat Harbour skirts the marine park situated to the North West of Boat Harbour township. No installation or maintenance activities is permissible within the marine park. If any work is to be conducted in this area, the exact boundaries must be known before any work is attempted.

At Boat Harbour the cable was hauled ashore, before terminating at the beach manhole. The cable is anchored in position using deadman anchors at the beach manhole and trenched to a required depth of approximately 2 metres to the low water mark. Articulated pipe is again installed over the cable for approximately 450 metres off shore to the beach manhole. From the beach manhole, the cable was hauled through ducts using standard hauling techniques, to the exchange located at the intersection of the Bass Highway and Port Road.

The submarine cable has been buried to a minimum depth of 0.6 metres, except inshore at Boat Harbour where the cable passes over a rocky sea floor. The As-Laid report fully details the burial achieved. The vast majority of burial was achieved by submersible cable plough, with joints, near shore sections and other sections not buried by the cable plough being buried by remote operated vehicle (ROV) using water jetting andlor divers using water jetting techniques.

Return to IN&T's Home Page