Upgrade in 2008-2009
The North Wellington Public Transport Study by GWRC and WCC considered four options for improved public transport: enhanced rail; bus on street; conversion to a guided busway; and conversion to light rail. On 16 November 2006 the GWRC Public Transport Committee and the WCC Strategy & Policy Committee accepted a "Do Minimum" option involving retention of the line and replacement of the current DM units with the same number of refurbished EM/ET class (Ganz Mavag) units; this required enlarging the tunnels and increasing platform clearances and lengths. GWRC have since had to change to using only the new Matangi units on this line because of the limited braking power of EM/ET class units on the steep grades
GWRC envisaged (2007) that the track through the tunnels would need to be lowered by 120 mm, depending on the new units. Lengthening of passing loops and platforms was also likely to be needed, and the estimated cost was $5 million. A programme of preparatory work for the tunnel upgrading commenced on 7 September 2008 and was completed in February 2009. Construction took place after 20:00 on Sunday - Thursday nights to minimise disruption to commuters, with services being replaced by buses. The seven tunnels were upgraded in January 2009 during a period in which the line was closed to all traffic. The work included:
- lowering the track and widening the side clearances in the seven tunnels
- lengthening the three crossing loops, allowing longer trains
- upgrading platforms by lengthening them and increasing clearances
- increasing clearances under two bridges: Lower a rail bridge in Ngaio Gorge (between tunnels) and lower the level of the track under the Raroa Station footbridge
- new power substation at Ngaio
Read more about this topic: Johnsonville Branch