The 90 metre tunnel will be ‘daylighted', essentially removing the tunnel roof and hillside above.

KiwiRail Chief Executive Jim Quinn said the project will enhance the capacity and reliability of a key transport link.

"The Midland Line links the West Coast with Christchurch and the Port of Lyttelton and is used extensively by coal trains as well as the popular Tranz Alpine passenger service," Jim Quinn said.

"The Kiwi Point tunnel was built in the 1880s at a time when railways were designed to carry much lighter and smaller loads. With the tunnel gone, this will remove one of the impediments to carrying larger loads on the busy Midland Line.

"The geology of the area means the tunnel lining has deteriorated. Daylighting it will remove the need for ongoing and costly monitoring and maintenance of the tunnel."

Kiwirail Network's engineering team is currently seeking expressions of interest for the project, with the aim to start work early next year. The project is expected to take four months to complete and the total cost is estimated at more than $1million.

The work will involve the excavation of more than 50,000m3 of rock- all above an operating railway and State Highway 7. The work will be scheduled around train movements and a traffic management plan, including a temporary rock-fall fence, will minimise the disruption to road traffic.

Jim Quinn said the company successfully managed a similar situation with the 2008 project to daylight three rail tunnels in the Manawatu Gorge above State Highway 3.

He said the decision to daylight the tunnel supports other recent investment in the line.

"The Midland Line is important, both for the movement of coal between the West Coast and Port of Lyttelton, but also as a popular attraction for international tourists. The investments made are designed to improve the reliability and capacity of the line including extended passing loops, replacement of timber bridges, and a planned signalling upgrade.

"In addition, new locomotives ordered to arrive in the second half of 2010 will release more powerful locomotives for use on the coal route. New passenger carriages being built at KiwiRail's Hillside workshop in Dunedin will be introduced into Tranz Alpine services in 2011."

KiwiRail Contact: Ruth Larsen 04 498 3383 / 021 804 906