The New Zealand Railways Magazine, Volume 1, Issue 6 (October 24, 1926)
Railway Yard Lighting
The problem of lighting a railway yard or similar area would appear at first glance to be a comparatively simple one, the solution being to erect a number of lamps, provide cables, and connect to the power supply. In reality the problem is not simple and is one which has been the subject of investigation and experiment for many years.
As a result of this research work there has been a great advance in the design of lighting appliances during recent years and this, combined with the growth of electrical power distribution, has made it possible to effect enormous improvements in yard lighting.
In designing a lighting installation there are a number of important points which must be considered, such as intensity and contrast. The human eye, although capable of adjusting its focus and being provided with an aperture which enlarges or diminishes so as to control the amount of light entering the lens, has certain limitations, and it is only by taking these into account that a satisfactory result can be obtained.
The object in artificial lighting is to obtain an effect corresponding to day-light, and, although it is obviously impossible to reproduce daylight illumination, something can be done by careful design and the use of modern lighting equipment towards this end.
In regard to intensity of light, it has been found by careful experiment that certain intensities are the most suitable for certain classes of work, and this effect can be comparatively easily achieved by the provision of lamps of sufficient candle power. The eye being capable of letting in more light by increasing its aperture can, within certain limits, make up for a loss of light.
The next point is contrast. Any form of yard illumination by means of a series of lamp units must result in alternate bright and dark areas, unless there were large numbers of lamps placed very close together, which would not be practicable. The result of these dark and light areas on the eye is that a continual effort is necessary in endeavouring to accommodate the eye to the different intensities. The same effect is noticed page 23 after looking at a bright light and then trying to see in a dim light, or vice versa. This contrast effect is shown in figure 1.
In practice the contrast is reduced as much as possible by suitably locating the lamps and keeping the candle power down to the lowest point to give the intensity necessary, and in the avoidance of shadows as far as possible.
A new form of lighting has been developed recently, which is known as “flood lighting.” Generally the idea is to provide only one or two points of illumination in a yard and from these points to flood the whole yard with beams of light. The lights are placed on high towers, 80 feet to 90 feet high, well above the ordinary line of vision, and the lights themselves consist of high power lamps and reflectors behind specially designed lenses. The beams of light from the towers at each end of the yard flood the whole yard from each end, with the result that there is little or no contrast, and a desired intensity can be arranged for by using the required number of lamps. (See fig. 2.)
Shadows cannot be altogether avoided, but owing to the general diffusion of light the resulting contrasts are not so great as with a number of isolated lights. The photograph (fig. 3.) shows the general flood lighting effect in a railway yard.
Should it be necessary to have a greater intensity of light in any particular part of the yard a special lamp can be provided on the tower and focussed to the point required.
Flood lighting generally mitigates to a very large extent the inherent disadvantages which exist with the present form of lighting, but flood lighting is, of course, suitable only for the larger yards.
A few installations have been completed in Australia, where results have proved satisfactory, and some installations are shortly to be put in hand on the New Zealand Railways.
The Hon. Sir R. Heaton Rhodes, Leader of the Legislative Council, writes as follows:—
“I desire to say that the arrangements made for the transportation to Rotorua of the Empire Parliamentary Association Delegates and members of the New Zealand Legislature were carried out in a most efficient manner, and I shall be glad if you will please convey to the officers concerned my appreciation therein, with special reference to the personal services rendered by Mr. Welsh.”