ROAD LIGHTING

Evening Post, Volume CXXIV, Issue 89, 12 October 1937, Page 10

ROAD LIGHTING

SAFER HIGHWAYS

ENGINEERING PRINCIPLES

THE HUTT TEST

| A technical discussion of the needs, principles, and means of highways lighting was placed before the conference by Mr. J. C. Forsyth, B.Sc., M:I.E.E. (Christchurch), who also presented a paper upon the same subject at last year's conference.

Investigations into means of reduc- . ing the appalling total of accidents had ■ demonstrated that the number could ' be effectively balanced by adequate [ lighting, said Mr. Forsyth. The object . of highway lighting must be to provide : lighting of such intensity and quality • that the road user could see as effec- | tively at. night as in the day time. [ There was no technical difficulty in • accomplishing that result, but in the 1 present knowledge of the art the cost 1 of that result was prohibitive. It con- ; sequently became necessary for the engineer to make the best use possible ' of all the factors, that the best result might be obtained for the expenditure available. Mr. Forsyth discussed the principles involved, types of lights, and installations from the technical aspect, and stated that the capital cost of the installation determined only from 30 to 33 per cent, of the annual charges required. Annual operating and maintenance charges were also analysed in detail, and from a comparison of costs per hour of using different types of lamps Mr. Forsyth found that the high efficiency of the gaseous discharge lamps (mercury and sodium) was largely offset by the very high cost of these lamps in New Zealand as compared with the cost of filament lamps, and that under present conditions the most satisfactory system for highways lighting installations was the constant current series system using gas-filled tungsten filament lamps. COST AND COLOUR. Mr. Forsyth said that his findings were in no way intended as a reflection upon gaseous discharge lamps, though they might be read as a reflection upon the very high cost of this equipment in New Zealand at present. With that high cost the use of the gaseous discharge lamp could not, he considered, be justified at the present time. Mr. W. G. Dawson spoke of the success of mercury-vapour lighting at Whangarei, wljere the system was introduced about three years ago and at the request of the Chamber of Commerc-- was extended to a total, of 120 lamps. Mr. Dawson did not agree with certain of the cost figures and findings of Mr. Forsyth. The objection of interference with colour was of no serious importance in Whangarei. The people had become quite accustomed to the lights and the only colours interfered with in fact were the'reds; other colours were improved. CONFUSION WITH SIGNALS. Mr. G. W. Wyles referred again to the possibility of hazard when gaseous discharge lamps were erected in proximity to railway yards and tracks, through drivers being confused by mistaking the glare of the lights through mist for track sigiials. Whenever such lights were placed near railway tracks it was essential that the fittings should give a short cut-off, even though that would entail more lamps and greater cost. . . HUTT VALLEY LIGHTS. Mr. E. F. Hollands (Hutt Valley Power Board) said that figures as to the demonstration at Lower Hutt would be available later. Referring to the possibility of confusion when, gaseous discharge lamps were erected near railway lines or harbour works, Mr. Hollands said that the Hutt Valley Board experimented with mercury vapour lamps last year and was immediately notified by the • Harbour Board that they should be put out. Members of the board and the staff went out in the Harbour Board tug, and it was quite evident that the m,ercury vapour lighting did have a bearing upon the leading lights of the harbour. That was the reason why these lights had no place in the present demonstration length, but it was the board's intention to erect another length of a different type of lighting higher up the Valley, where the lights would be out of sight from the harbour. In reply to the several points raised, Mr. Forsyth said that his paper was primarily upon highways, not city lighting, and his emphasis upon cost had reference to present conditions in New Zealand.