198703 – Pallister – New Zealand Railways Corporation: North Island Main Trunk Electrification “The Signalling Project”

The Signalling Project is composed of two separate contracts, Stage One and Stage Two. The specification for Stage One was available in March, 1983. The Stage One Signalling contract was awarded to Westinghouse- McKenzie-Holland Pty. Ltd. on the 22nd December, 1983 – just before the Christmas closedown of most Australasian Engineering companies. Westinghouse-McKenzie-Holland Pty. Ltd. is a wholly owned subsidiary of Westinghouse Brake & Signal Co. (Australia) Ltd. The Signalling Contract was for the design, manufacture, supply, installation, testing, commissioning and guarantee of the signalling system for that portion of North Island Main Trunk Railway between Palmerston North and Ohakune inclusive. The contract period was one hundred and fifty weeks.

At the time of letting the Stage One Signalling Contract a total of twenty two crossing loops, including two junction stations, were to be resignalled. of Ohingaiti. This was later reduced to twenty one with the elimination The new signalling system was required to be immune to the effects of the 25-0-25 KV North Island Main Trunk Electrification Project, overhead traction system. A conventional relay interlocking was to be provided at each crossing loop, the relay rooms being positioned generally at the centre of each loop. For some of the crossing loops north of Marton, operational considerations required half block intermediate signals to permit following moves in these block sections. longer Mains power was provided by New Zealand Railways Corporation at each relay room, a diesel motor/alternator set being provided to furnish standby power in the event of interruptions to the mains supply. Power was reticulated from the relay room to signalling locations at 400 volts AC and stepped down to 110 volts in the location case.

Work commenced on the Stage One cable route in July, 1984, at Palmerston North. of The first signalling commissioning was that of Maewa, a simple crossing loop, on 26th November, 1984, less than twelve months from award contract. Cable route construction and signalling installation generally moved on a south to north front. The cable route to Ohakune was completed by December, 1985, with signalling commissionings taking place progressively until 22nd September, 1986.

For Stage One a site depot was established at Marton in the junction between the North Island Main Trunk Railway and the Marton to New Plymouth Line (MNPL). Swampy ground was filled, fenced and stores and administration buildings erected. By coincidence, the site office for New Zealand Railways Corporation staff was established nearby – just on the other side of the MNPL.

The Stage Two Signalling tender documents were received together with a formal invitation to tender on 13th March, 1985. The tender was submitted on 26th April, 1986, and the contract let to Westinghouse- HcKenzie-Holland Pty. Ltd. on 31st July, 1986. Stage Two continues northward from the end of Stage One at Ohakune to Hamilton and at tender time consisted of twenty six interlockings, including one junction. The Hamilton Yard, the junction to the East Coast Main Line and portion of the Te Rapa marshalling facility were also included. Two interlockings were removed at the time of award of the contract, with alterations also occurring to other loops. The contract period was one hundred and sixteen weeks. Due to Civil Engineering constraints, the cable route construction was not to commence before 13th January, 1986. Commissionings commenced in July, 1986 and will continue until 12th December, 1987.

Two site offices are utilised for Stage Two, with the main depot being located at Taumarunui, the C.T.C. Control Centre. A subsidiary depot was established at Hamilton for the commissionings in that area.

The major areas of material supply, installation activity and circuitry will be considered in detail.