The New Zealand Railways Magazine, Volume 3, Issue 11 (March 1, 1929)
The trial of the newly imported “Garratt” articulated locomotives on our lines draws attention anew to the scale and scope of transport developments in recent years. In 1924 we had six hundred and fifty-five locomotives in operation built in forty-seven classes. The tractive effort of the largest of these was 26,620lbs., and there were only eighteen locomotives of this type. At that time only one-third of our locomotives had a tractive effort of 20,000lbs. or over.
Last year our total locomotive stock was six hundred and seventy-eight, the proportion of higher powered engines had been increased, an additional seventy-four being capable of 20,000lbs. or over of tractive effort, and the number of classes had been reduced to forty—but still we had no unit capable of higher tractive effort than the “X” class (26,620lbs.) engine, weighing, in working trim, 94 tons. The new “Garratts,” just introduced, with their 51,580lbs. of tractive power and a working weight of 146 tons, really constitute the commencement of a revolution in locomotive practice in New Zealand, and bring the general question of transport under review once more.
To carry locomotives of this type it became necessary that the whole permanent way should be considered anew, and the strengthening of bridges and other track structures undertaken before bringing these monsters of the iron road into operation.
Their capacity, however, was so well related to the needs of our traffic that the additional expenditure on permanent way strengthening would be fully warranted.
A somewhat similar position has arisen upon the main highways of New Zealand. Commercial motor vehicles of greater power and weight have been put into use, and the Government and local bodies responsible for the upkeep of the roads have found it necessary to greatly strengthen the roads to enable them to stand up to the traffic. It is all simply a question of engineering—a certain class of road (whether a highway or a railway track) can only carry vehicles of a certain weight. Its character and strength must be changed according to the weight of the vehicles it is required to carry. But the Railway, the user, has to find the money for any expenditure upon its tracks, whereas the users of commercial motor vehicles do not bear the cost of road improvements—that cost is borne by the Government or the local body concerned. And some local bodies are becoming seriously concerned because of the loads which the heavier types of road vehicles page 6 are putting on their rates. They find that roads built for light traffic have to be reconstructed and expensively maintained, and they cannot see the value for their money.
If the Railways could take advantage of heavier transport units and shoulder on to some third party the expense of the additionally-strong tracks needed, no doubt there would be a strong desire to move steadily along in the direction of still heavier and more powerful locomotives, and the economic advantage to the Railways would be great indeed. But as the Railways and their road competitors are not nearly on a parity in regard to the charges for maintenance and service they have to meet, the task of providing that the most economical transport service may be secured for the country is decidedly difficult. In the meantime experimentation in big engine transport is fully justified. The principal ground for this belief is that it offers scope for operating economies more promising than that to be found in almost any other field, and its initiation in New Zealand has already indicated a possible solution to some of our most pressing problems.