Did you know?

Many RTA engineering and construction projects involve innovative approaches and engineering feats. Some of the more interesting facts about the Sydney Harbour Tunnel are tabled below.

Crunching the numbers

• In 2005, the annual average daily traffic volume using the tunnel was 86,800 vehicles.
• As part of the Sydney Harbour Tunnel Project, a bus lane was introduced on the Sydney Harbour Bridge. In 2005, during the AM peak period, the bus lane on the Sydney Harbour Bridge carried on average over 30 per cent more people per hour than the other seven general traffic lanes combined.
• The Sydney Harbour Tunnel has 22 carbon monoxide monitors, 14 supply fans and 16 reversible exhaust fans.

How low can you go?

The tunnel descends to 27 metres below mean sea level.

Construction outpost

One kilometre of the Sydney Harbour Tunnel was constructed using the ‘immersed tube method’. This consisted of eight 120 metre pre-fabricated concrete sections sealed with a waterproof membrane. These submersible sections were constructed in a dry dock at Port Kembla, before being towed to Sydney Harbour and lowered into a 12 metre trench by asystem of pontoons and control towers.

Walking under water

To commemorate the opening of the Sydney Harbour Tunnel in August 1992, the public were invited to walk the length of the Tunnel.

Photo credit: Transfield Holdings