Executive summary
On Saturday 4 December 2004, a Tranz Metro electric multiple unit passenger train travelling from Wellington to Paraparaumu became disabled between Kaiwharawhara Station and Tunnel 1 when the traction overhead contact wire failed due to tensile overload. The failure was brought about by a combination of poor eletrical contact between the contact wire and stirrup clamping plates, and a build-up of corrosion products.
On Monday 24 January 2005, a Tranz Metro electric multiple unit passenger train travelling from Upper Hutt to Wellington became disabled between Petone and Ngauranga when the traction overhead contact wire failed. The cause of the failures was similar to the incident that occurred on 4 December 2004.
There were no injuries.
The safey issues identified were:
• the early detection and replacement of safety-critical components before failure
• the safety of passengers on disabled trains
One safety recommendation has been made to the Chief Executive of ONTRACK and one to the Chief Executive of Toll NZ Consolidated Limited.