N.Z. TRAINS

Evening Post, Volume CXVII, Issue 127, 31 May 1934, Page 12

N.Z. TRAINS

CAN THEY RUN FASTER ?

GAUGE NOT THE HINDRANCE

GRADES AND CURVES

Railway speeds are not liniitea so mueh> by a narrow gauge as by the curves and grades of the line. The rolling-stock arid loads are proportion-, ed to the gauge, .and high speeds are possible on straight, level stretches even on the New Zealand gauge of 3ft 6ih. Suggestions that there is scope for the improvement of speeds on New Zealand railways have been made, but the Department, answering a correspondent of the "Railway Circle" (South Africa) shows that in view of the grades and curves of the New Zealand system, the results obtained are very creditable. SIXTY MILES PEE HOUR. Drawing attention to a striking speed experience of his on one of the 3ft 6in gauge main lines of the South Island the correspondent states that the Christchurch express, made up of thirteen coaches of a total weight of 335 tons, covered the §5.5 miles from Rakaia to Chnstchurch in 48min lOsec from stop to stop, but as a 20-mile-per-hour speed limit over the Rakaia viaduct, which is over a mile long, caused the- first ±.J miles to occupy lOmin 42sec the next 2o miles were covered in 26miri 31i sec : This gives an average speed of 000 miles per hour, mostly on slightly falling grades, but the maximum speed was 60.9 miles per hour, and was the more noteworthy, as the driving wheels ?L -• .ocomotive were no m°ro than «t bin in diameter, and the cylinders Inn m diameter by 26in stroke. "At present," ho concludes, "the scheduled running speeds of the best long-distance expresses in New Zealand average only 32 miles per hour, excluding stops, and otner than the mountainous sections there seems, on this showing, scope for improvement." .-;..- It is not only the "mountainous sections" which pull down the speed, but tho numerous curves. Commenting on the percentages of straight and curved line gradients on the New Zealand tracks, the assistant editor of the "Railway Gazette" (London), says: ".There are, I should think, few railways irf the world that have a higher percentage of steep gradients and sharp curvatibns, when the. whole service is considered." r BRIDGES SLOW SPEEDS. Taking the North Island Main Trunk as a sample, it is pointed out by the Railway Department that a rather remarkable speed performance is achieved for the total distance.trayelled,"426 miles in just over 14 hours. Tunnels range from 250 ft: to' over 3515 ft in length: There are 22 ' viaducts and bridges, five of which are over 100 ft above'their' river beds, two over 200 ft, and one, Makatote viaduct, 260 ft above its stream level, with a span of 860 ft. The length of~the span of these bridges varies from 200 ft to 1185 ft. :; It is the grades and curves which1 prove the greatest obstacle to speeds. Compared with most other railways in the world, they are striking. . . UPS AND DOWNS. There is a climb from Auckland to Poro-o-tarao (of 1148 ft, the line drops to 560 ft at Taumarunui, and then, in the 32 miles to National Park, rises to 2636 ft. At Ohakune it drops to 2018 ft, but again rises to reach its... highest point at Waiouru, 241. miles from Auckland, of 2660 ft, or more than half" a mile above sea-level; Thence tho : descent ;is fairly rapid to Palmerston North, which is only 103 ft above sealevel. From there, thero . are. two climbs over the Pukerua and Johnsonvillo rises., The quality of the construction work is shown in the.maintenance of a start-to-stop average. speed, from Auckland to "Wellington, of 30 miles per hour, which means that on parts of the route very high" speeds have to be maintained. l : : About half the. total milage of the New Zealand railways is constructed on grades steeper than 1 in 200, while one mile in. every eleven is on a grade steeper than 1 in 50: "■■■.'•■ ' SHORT-RADIUS CURVES. Of the total milage nearly 6 per cent, has curves of 10-chain radius and under, 12 per cent., has curves of 15-chain radius and under, and 26 per cent., or more than a quarter of the total, consists of curved track and there are 54} miles of bridges. '