User:KiwisFlying/New Zealand interisland tunnel

The Interisland Road/Rail Tunnel was located underneath the Cook Strait of New Zealand along State Highway 1 and the North Island Main Trunk Line. The use was subject to a toll. With a length of 74.1km (46 miles), the tunnel ranked as one of the longest road tunnels in the southern hemisphere.

Location
The tunnel crossed under the Cook Strait, a body of water between the Tasman Sea and Eastern Pacific Ocean which seperated New Zealands North and South islands. The north portal was connected to State Highway 1 south of the main airport in in Wellington, in the North Island, while the southern entrance was also connected to State Highway 1 in the South Island, in Blenheim.

Plans for the tunnel were originally drafted during the 1960s and were confirmed during Robert Muldoon's "Think Big" public works projects as part of the Third National Government. Construction began in 1971 and with the assistance of overseas engineers, primarily originating from Japan, the tunnel was completed on schedule to a state opening on 21 June, 1975.

The road tunnel should not be confused with the sea-based Interislander which which is a ferry service which crosses the Cook Strait and carries a variety of passengers, vehicles, and train carriages between Wellington and Picton.

Construction
Planned as a two bore tunnel from the beginning, the first bore of the Road Tunnel was completed in 1975 with a total length of 74.1 km. Plans for the construction of the second, parallel tube were abandoned in 1988 and not bought up again until the 2011 Canterbury Earthquakes (see below).

2011 Collapse
On 22 Feb 2011, at 12:51 p.m., a magnitude 6.3 earthquake in the region of Canterbury led to an emergency evacuation of the tunnel which led to the injuries of three people. The earthquake and aftershocks caused areas of the tunnel along the strait to be snapped from their foundations and what was originally intended as a temporary closure of the tunnel became indefinite.

The tunnel was so badly damaged by the aftershocks from the earthquake that it was decided to permanently close the tunnel to all road and rail traffic. Repairs to the tunnel structure and damaged ventilation equipment were estimated at almost NZ$6 billion.

On 25 Sep 2011, seven months after the emergency closure of the tunnel, a section was recorded collapsing approximately 13 km north of the southern portal in Blenheim. The remaining sections of tunnel have flooded with seawater and a reopening of the tunnel is now considered impossible from an engineering standpoint.

Category:Road tunnels in New Zealand Category:Tunnels completed in 1975 Category:Base tunnels Category:Tunnel disasters