The New Zealand Railways Magazine, Volume 13, Issue 4 (July 1, 1938.)
Capital Costs per Mile To-day
Capital Costs per Mile To-day.
High capital costs per mile relatively to those of other railways of 3 ft. 6 in. gauge might be expected to exist in New Zealand on account of the difficult nature of the country. The longest bridge on the South African Railways (with four times New Zealand's mileage) measures 2,974 feet, as against two in New Zealand of the order of a mile on the Canterbury Plains alone. The longest South African tunnel measures 1,001 yards; the longest in New Zealand 51/4 miles.
It is nevertheless rather staggering to find that the capital cost per mile of the New Zealand Railways to-day is about £16,500, as against £5,000 contemplated page 18 page 19 in 1870 and £7,000 actually achieved in the ‘eighties.
Even on the early constructed lines the capital costs have risen because of the increased density of traffic. This has called for a greater amount of rolling stock per mile, larger buildings, heavier rolling stock, stronger bridges, track duplications, installation of elaborate signalling devices to secure safety in working, and provision of additional equipment on rolling stock to ensure safety and comfort, e.g., Westinghouse brake (installed about 1900), steam-heating on main line cars (installed progressively over the last 25 years), and so forth.
Many of these improvements such as the installation of the Westinghouse brake were not effected before their time; and to judge from some of the official reports of the late ‘nineties locomotive engineers and train crews went in daily fear of a serious runaway.
The early railways in New Zealand—as in most young countries—were designed primarily with a view to rapid opening up of the country at a minimum of capital cost. The rolling stock and the bridges were therefore light in construction and the tracks represented the nearest possible approach to “surface” lines. It follows that they were characterised by heavy gradients and sharp curvature. In Natal practically no heavy earth works or tunnels were needed under this policy, but the result was 1 in 30 grades and curves as sharp as 300 ft. radius. These characteristics served well enough when the main object was cheap and rapid opening up of the country; but they are not good characteristics of a railway carrying a heavy volume of traffic such as the New Zealand main lines during the past 40 years, because they do not make for speed and economy in operation. Sharp curves, for instance, necessitate a reduction of speed in the interests of safety, while, by increasing friction, they also of themselves tend to reduce the speed of trains. Whether the track is single, double, or multiple, also affects operating efficiency and is an important consideration when traffic grows beyond a certain point. If a single track only is provided, frequency of crossing places, the length of loops, and the existence of safety devices such as electric train tablet or automatic signalling (the latter both saves staff and gives a closer headway than tablet between succeeding trains) all have a bearing on rapidity of transport and economy of operation.
Up till well into the present century the only duplicated line in New Zealand was a length of some seven miles in the vicinity of Christchurch; and as recently as 1936 there were only 77 1/2 miles of double track out of a total route mileage of 3,317. Duplication works are, however, in progress on the Main Trunk line north from Wellington, and south from Auckland, which are likely at least to double this figure within the next few years.
Considerable expenditure has, during the past 25 years, been incurred in New Zealand in order to eliminate steep grades where traffic is heavy. This is a proceeding that pays whenever the saving in operating costs is sufficient to meet the interest bill involved, e.g., Mosgiel—Dunedin, Mercer—Auckland, Wellington—Tawa Flat. Between Dunedin and Palmerston South the ruling grade is 1 in 50. This last is rather steeper than is consistent with satisfactory modern working conditions, and in practice in New Zealand anything steeper than 1 in 70 has in recent years been avoided wherever possible. In England it is not deemed good practice to construct railways with steeper gradients than 1 in 100, and the standards of future main line construction are now 1 in 70 in Tasmania, 1 in 80 in South Australia and West Australia, and 1 in 75 in Queensland.
The effects of gradients on the efficiency of railway operation may be readily appreciated if it is pointed out that an engine capable of hauling 686 tons over a grade of 1 in 150, will haul only 494 tons over a grade of 1 in 100, and 249 tons over a grade of 1 in 50. Speeds are affected in about the same ratio; thus a train weighing 220 tons and attaining a speed of 15 miles per hour on a grade of 1 in 50 would attain a speed of 30 miles per hour on a grade of 1 in 100 and 40 miles per hour on a grade of 1 in 150. When the ruling grades between Penrose and Mercer were altered a quarter of a century ago from 1 in 40 to 1 in 100 (at a cost of about £1/4m.), the locomotive that could previously haul only 162 tons over this route could take 494 tons.
There has been a considerable improvement in the equipment of New Zealand passenger carriages, which has somewhat increased the dead-weight in relation to the tractive force of locomotives. The more recent increases have been effected largely in the interests of providing a greater standard of comfort in the face of motor competition. With the opening of the North Island Main Trunk line in 1908, the North Island adhered for many years to standard car types, viz., 50 ft. Main Trunk (8 3/4 ft. wide) and 50 ft. Main Line (7-5/6 ft. wide); but the tares of such rolling stock have progressively increased as a result of (a) fitting electric lighting (run from batteries), (b) provision of steel plates, and angle iron anti-collision ends, and (c) providing separate ladies’ and gentlemen's lavatory accommodation in Main Trunk cars. Later built cars for the Auckland —Rotorua service, the North Island “de Luxe” sleeping cars, and the new North Island Main Trunk ordinary cars show an appreciable increase in tare due to heavier bodies, disc wheels, more substantial design in underframe and car bodies, larger lighting generators (to cover fans, tea and coffee urns, etc.). larger water tanks, and heavier draw-gear.
Thus during the past 20 to 25 years the weight of North Island Main Trunk express carriages has increased almost 20 per cent.; while the increase in the South Island is nearer 40 per cent., as against increases of 15 per cent. in South Africa, 8 per cent. in Queensland, 3 per cent. in Tasmania, and almost stationary tares in West Australia.
Improvements in the design and construction of steam locomotives have been stimulated by the increasing congestion page 20 page 21 of traffic as well as by the development of heavier rolling stock. Expensive track duplication can sometimes be postponed by running heavier trains at higher speeds or even at the same speeds as before. The high cost of fuel, the increasing power of the locomotive, and the competition of electricity as a tractive power have forced steam locomotive designers to aim as far as possible at thermal economy with increasing power. Progress has therefore been in the direction of heavier, faster, more powerful and more economical engines; and has been achieved by the use of larger boilers fitted with superheaters, improved designs of furnace and lighter moving parts made of stronger materials (e.g., nickel steel), as well as by straightening curves and flattening gradients.
During the past 20 years the average tractive force of locomotives in New Zealand has gone up 35 per cent., and in South Africa 40 per cent., while the average weights of locomotives have increased by 50 per cent. in New Zealand and 66 per cent. in South Africa. Subsequent to the Boer War a good deal of British capital went into the restoration of Railways, with the result that road-bed standards in South Africa were brought up to those then ruling as British practice. Road-bed and bridges, therefore, have-not hindered locomotive development to the same extent in South Africa as in New Zealand; where bridges, weights of rails, etc., were, at the time they were installed, considered adequate for locomotives then running, but have since considerably restricted locomotive design and have necessitated reboilering. This, in turn, has perpetuated a number of types of locomotive built between 1898 and 1901 (e.g., “B,” “U,” 1901 “Ub,” “Uc”), while numbers of the “F” type built in the ‘seventies have had to be retained to work certain South Island wharves, the Kaihu Valley Railway, etc.
When in 1901 the “Q,” or first “Pacific” (4-6-2) type of locomotive was designed in New Zealand and built in Philadelphia, there were only about 350 miles of line on which the 13 engines of this type could safely run, and then their speed on numerous bridges had to be restricted.
For some years following 1916 New Zealand was practically restricted to building the “Ab” type of locomotive and its variants, “Ws,” and “Wab,” for train operation. The strengthening of bridges between Wellington and Auckland was completed at the same time as the first of the new “K” locomotives was ready to run. (These locomotives have a tractive force of 30,815 lbs., or just over 1 1/2 times that of the “Ab”). On the South African railways (which have the same gauge as New Zealand) just half the locomotives have a tractive force greater than the New Zealand “K” and only one-quarter have a lower tractive effort than our “Ab.”
The building of the new “K” engines was part of a policy to replace in the North Island locomotives that have become obsolete (e.g., “J,” “Wb,” “Wd”), and to release North Island “A” and “Q” class locomotives for South Island use. This rendered unnecessary the reboilering of the older flat valve classes in the South Island (such as 1899 “Ub” and “Wd”) and postponed heavy track work that has not been considered to be justified by present traffic—although even so it has been found necessary to strengthen many of the bridges on the Otago Central Railway to accommodate even the “A” and “Q” engines. These are now considered of insufficient tractive force for the heavy Main Line passenger trains of the North Island Main Line and Branches.
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