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The New Zealand Railways Magazine, Volume 2, Issue 8 (December 1, 1927)

[section]

The name Middleton as far as Railway history goes had, up to the 12th October, 1927, been associated with an unpretentious flag station on the outskirts of Christchurch.

From the date mentioned it has become identified with one of the most modern of marshalling and rail traffic parking places in Australasia. This yard -the outcome of years of experience and experimenting in New Zealand and overseas countries-has been designed for the complete handling of the longest goods trains.

View of main marshalling yard, taken from No. 1 flood-light tower.

View of main marshalling yard, taken from No. 1 flood-light tower.

The division of a train from the time it arrives till its different parts are stored away in the various roads, is controlled by an important feature of the yard known as the “Hump Track” which is situated between the arrival and classification yards.

It is the aim in the design of a big marshalling yard such as Middleton, to bring the movements down to the lowest minimum possible. This end is attained by the “Hump” principle.

The operation of the “Hump” will perhaps be of interest to readers. Briefly, then, the “Hump” operation of trains is as follows:— A goods train arrives and is brought to a stop in one of the arrival sidings at the south end of the yard. The train engine is then uncoupled and taken to the depot and the “Hump” engine (although called the “Hump” engine it signifies merely that it supplies the power for pushing trains up to the crest of the “Hump” track,) is at once attached behind the train.

The wagons, in the meantime, have been examined for destination points, chalk marked, and the couplings (excepting the hooks) are unfastened. The whole rake is then moved up to the crest of the “Hump” where hooks are lifted and the wagons allowed to run down the incline-gathering momentum on the way to take them beyond fouling points in the yard- This latter movement is controlled by an electric indication signal which, by means of colour lights, conveys to the driver of the “Hump” engine the movements required.

This signal is controlled by the shunter in charge by means of a selective radial arm fixed in a part at the “Hump” crest giving the following indicators: (Red-“stop”) (one yellow-“Go away”) (“Come” two yellow) (“Slack up” three yellow.) The destination of the wagons running down the “Hump” can be seen by the chalk marks on their ends, and the shunter on the points lever at the controlling neck, and his assistants directs them accordingly.

The indication signal is repeated so that the crew of the “Hump” engine can see it when working at a distance, as with a long rake.

The yards are 84 chains in length and at their widest part carry 31 roads.

One of the main features of this yard is its signalling and power interlocking system. Running adjacent to the main south lines and having entrance and departure routes from both directions as well as a departure route from the middle, it was necessary, whilst observing “Safety first,” to give as much flexibity as possible so as not to hamper movements within the yard.

The signalling system chosen is the now popular and up-to-date three position colour light system of signalling which is already installed at various places in each island and working satisfactorily.

The Signal Cabin is situated in the centre of the yard opposite the “Hump” track, and is built of brick. It is the only brick structure of page 37 its kind in New Zealand, and makes an imposing setting for this all important yard.

No. 1 Flood-light tower, looking towards Christchurch.

No. 1 Flood-light tower, looking towards Christchurch.

It has two stories, the upper half housing (in its handsome cabinet of maplewood) the 64 electric lever frame relay racks, and the yard-master's office-the latter being partitioned off. The lower half is the Shunters' Mess Room. Other conveniences (wash basins, etc.,) are provided in the adjacent out-buildings.

All single and crossover points, double and single slips and trap point movements, are operated by points motors. Moreover, all signals are detected through the points. Every movement between the arrival and classification yards is controlled by the cabin, and every possible signalling route has been arranged for. Some of the points movements are over half a mile away from the cabin and could only be controlled by a power system capable of giving reliable indication to the signalmen. The levers operating points in the cabin frame cannot be placed in their full “Reverse” or full “Normal” position, as the case may be, unless the points switch has moved over to its required position and this, in turn gives the proper signal indication to the driver.

The lighting of Middleton Yard has, in view of the large area of the yard and steady volume of work required to be dealt with throughout the night, received special consideration. The latest system of flood lighting has been installed and is quite a special feature of the yard. The lights are grouped on three towers 90 feet in height (one at each end of the yard and one in the middle) and are of 6,000 c.p., 5,000 c.p. and 2,000 c.p. respectively. The highest candle power is directed on that portion of the yard where the heaviest work is done. The flood-light towers impress one when seen and resemble immense “Meccano” structures. They were made by a Canadian Company and are built of mild steel, set in concrete foundations. They have been designed to stand very high wind pressures.

The lamps are from the Pylo National Company and are of the “non glare” type. A most remarkable feature of the lamps is that one can stare into any of them and then, immediately afterwards, read a newspaper. On the opening night the whole illumination resembled that of the daylight hours and was acknowledged by experts to be the finest yet seen. Passengers from passing trains had their faces to the windows wondering what new phenomenon was visible. This lighting system is the same as that now installed at Timaru, Greymouth, Thorndon, Frankton, Otahuhu, Westfield and Auckland.

Arrival of First Train at Middleton.

Arrival of First Train at Middleton.

page 38

Full telephone conviences have been provided at Middleton. There are six yard telephones (connected with a hand speaker) from any of which an order can be given to the signalman who can answer, if necessary, by switching on to the cabin telephone. A connection is also made with the Christchurch-Oamaru train control system, with Christchurch Railway, Addington saleyards and Show grounds.

The power for operating and lighting the yard is taken from the Addington substation (Lake Coleridge supply) and is fed to the Department's high tension wires at Cutler's Road. Three transformers 3300–110 volt supply the signalling requirements and are of 20 K. V. A. capacity.

The lighting supply is 3300–230 volts for which three transformers are used varying from three to seven, K. V. A. capacity. (This also includes power for pumping plant etc.) The whole installation is an up-to-date job and will be a memorial to a progressive policy.