Sydney's Harbour Tunnels
- Road Tunnels
- Historic Tunnels
- Military Tunnels and Bunkers
- Forgotten Tunnels on the City Circle
- Railway Tunnels
- Harbour Tunnels
- Sydney's Lost Tunnels
- Sydney's Abandoned Railway Tunnels
- Underground Reservoirs
Very few people know that there have been not one but three tunnels cut under Sydney Harbour. The first, sunk near Birchgrove Primary School by Sydney s only coal mine, was dug between 1897 and 1902 to mine coal from almost one kilometre below the Harbour floor. It stretched east under Balmain for more than a kilometre to coal workings bounded by Mort Bay, Snails Bay, Balls Head and Goat Island. The coal, similar to that mined around Wollongong, was considered excellent for steaming and coking and an estimated 681,000 tonnes was mined from 1902 to 1931.
The Sydney Harbour Colliery was and remains the deepest coal mine ever to have been sunk in Australia. The mine's two circular shafts, named Birthday and Jubilee to commemorate Queen Victoria's birthday and the Diamond Jubilee of her reign, were lined with brick from top to bottom, as was a horizontal tunnel driven between the Birthday Shaft and the dock on Iron Cove.
Manns Point, Greenwich
The second tunnel under Sydney Harbour, which preceded the current road tunnel by 70 years, passes under Sydney Harbour from Long Nose Point on the tip of the Balmain Peninsula to Greenwich many hundreds of metres above coal mine tunnels in the same vicinity. Constructed between 1916 and 1926, it was part of an important communications link, having been constructed to bring electrical power to the railway and tramway systems of the North Shore from the recently completed Ultimo Power Station.
It was the biggest such venture of its kind to be undertaken in Australia without overseas assistance. The tunnel is lined with concrete in some areas, cast iron in some and bedrock in others. At the centre of the tunnel is a large chamber where pumps were located to remove water. One side of the tunnel is lined with reinforced concrete shelves to house the electricity cables. The tunnel still holds twelve cables, 8 x 11,000 volt and two 50 pair communication cables. In 1952 the Electricity Commission took over all power generation in Sydney but the railways retained the tunnel and cables which continued to carry electricity despite the tunnel having become flooded due to a lack of adequate maintenance. Use of the the tunnel ceased in 1969. Its northern entrance is marked by a concrete block placed over it in the reserve on the headland of Manns Point. Visitors to Manns Point will enjoy a good view of the Harbour in all directions, as well as observe at close range the ship-loading activities at the neighbouring Shell Oil Refinery Terminal.
UBD Map 6 Ref F 13
The idea of a transport tunnel under the Harbour was first proposed by two Sydney businessmen in 1885. Their scheme was for twin tunnels, one for trams and one for horses and pedestrians. They offered to build it at their cost but charge a toll over a period of years so as to recoup their investment before handling the tunnels over to the State Government. The proposal was rejected by the Government of the day because it was considered too dangerous. Five years later, a Royal Commission inspected eight suggestions for a Harbour crossing, one of which was for twin tunnels at a proposed cost of 600,000 pounds.
The next suggestion of a tunnel was raised by Chief Engineer John Bradfield around the turn of the century in a major review of Sydney s transport needs, a proposal from which the Harbour Bridge eventuated. Bradfield s idea was for rail traffic only though in the 1980s, when the idea of the present tunnel was birthed, it was for road traffic only. A tunnel was again promoted in 1954 when Harbour Bridge traffic had become very congested. The idea was scrapped in favour of converting the two railway tracks on the eastern side of the bridge to motor vehicle lanes. This plan was effected in 1959. The two lanes thus created were joined to the newly completed Cahill Expressway in 1962 which redirected two lanes of traffic across the front of Circular Quay to the eastern suburbs rather than let them find their way through the city centre.
In 1982, a second bridge crossing was proposed but rejected in favour of a tunnel as there were no corridors left in which to build a new north-south freeway. In June 1987 an agreement was signed for the Sydney Harbour Tunnel Company, a company formed by a Joint Venture to design, construct and operate the Tunnel. The period of operation would be 30 years, finishing in the year 2022 at which time the Tunnel would be handed over to the Government of NSW free of all costs. It comprised of a combination of two land tunnels on the North and South Harbour connected by an immersed tube tunnel section located in a trench dredged in the Harbour bottom from a point near the north east pylon of the Harbour Bridge to alongside the Opera House.
Constructed between January 1988 to August 1992 at a cost of $560 million, it has a land tunnel length of 1.3 kilometres (900 meters on North shore, 400 meters on South Shore) and a marine tunnel length of 1 kilometre. At its lowest point, the tunnel is 27 meters below mean sea level. The tunnel consists of 8 reinforced concrete immersed tube units, each 120 meters long and weighing 23,000 tonnes. Each unit was prefabricated in Port Kembla, towed to Sydney, floated into position, sunk to rest on the Harbour bed, emptied of water, sealed and then locked to its adjoining sections. The underwater sections of the tunnel were connected in March 1991. The first official crossing was made by the Governor of NSW, Rear-Admiral Sinclair and 17 year old apprentice carpenter Charles Nott on 31st March 1991. It was opened to road traffic in August 1992.
The four lane tunnel has a traffic capacity of 2,000 vehicles per hour. Traffic is monitored by loop detectors every 120 metres and employs more than 30 closed circuit cameras. It is lit by 8,000 fluorescent tubes. Ventilation is by 14 supply and 16 exhaust fans, each one reversible and up to 2.5 metres in diameter. The 2.3 km Tunnel has cut crossing time by 10 minutes in peak hour and is said to save 13 million litres of fuel a year by reducing bridge traffic by up to 60,000 vehicles per day. With two lanes north and two south, running parallel in separate sections, it has a design life of 100 years.