D.—2a

16

indicated on a grade not steeper than 1 in 60 on the straights, and compensated proportionately on curves ; and when it becomes necessary to relay the line through the wearing-out of present rails and rotting of sleepers the new work can be done on the new formation without any me)re cost, and probably without as much as woulel be; necessitated by the ordinary relaying operations. In conclusion, I consider that the solution of the Rimutaka crossing by railway will be; best solved by— Firstly, driving a tunnel on the lines indioateel above;, and utilizing the material to form a bank (the basis of a future ele;viation) between Cross Creek anel Pigeon Bush. (Line' I.) Secondly, as business develops, construct a deviation between Upper Hutt and Mungaroa according to line 2. Thirdly, when ordinary maintenance requirements necessitate it, relay the line between Cross Creek anel Pigeon Bush upon the; formation previously referred to as having been made from the tunnel spoil. (Lino 3.) In this connection also the following extract from Mr. E. H. Hiley's 1914 report is interesting : — Train-working on the Wairarapa line; is greatly interfered with by the heavy gradients existing between Upper Hutt and Summit, and the Rimutaka Incline between Cross Creek and Summit. The grade of the latter is lin 15, and the length 2 miles 79 chains. Special engines have to be' employed exclusively for this portion of the line. The maximum load per engine is 60 tons elead-weaght (say, about 20 tons actual traffic) ; frequently four engines are employed to haul a train of 240 tons, deadweight, from Cross Creek to Summit. The minimum, time, for the is forty minutes. Every train has to be remarshalled at the Summit anel similarly at Cross Creek. This involves a loss of at least fifteen minutes to a train at each station. On an average one hour twenty minutes is required to negotiate the three-mile journey up the incline. This puts a definite; limit upon the amount of business from the Wairarapa which can be dealt with. The cost per engine-mile is 3s. lei. A special track with a third rail for gripping and braking purposes has to be; maintained at considerable additional expense compared with the ordinary track. The impe)rta.nce of this route anel the productivity of the country which the existing anel projected railways will se;rve justify consideration of the abandonment of the incline and the construction of a deviation with gradients that will enable' all trains to be; worked with the standard types of engines, A really satisfactory service via the Wairarapa route is impracticable while trains have to be worked ove;r the; Rimutaka Incline, A considerable expenditure will be involved in carrying out the deviation, but the work, nevertheless, will have to be considered in the near future. TAWA FLAT DEVIATION. Report by Engineer-in-Chief, Public Works Department. Before the Government makes any definite decision em the; question e>f starting the Rimutaka Deviatiem, 1 am of the opinion that this should be considered in conjunction with the'question of a deviation to avoid the very steep grades existing on the presemt line leaving Wellington for the west coast. I refer particularly to the grade between the; Esplanade and Khanelallali. Before it is possible to compare any proposed line with an existing line' it is necessary to recollect that the existing line; is reaching the limit of its oapacity, and consequently must be double-tracked within a short time unless some deviation is made ; and in fact, if a dc;viation is made, it will still rorpiire to be a double-track line before many years. The; present traffic at Thorndon Station amounts to 1,218,T00 tons outwards and 1,186,255 tons inwards per annum, anel the rate of growth since 1910 indicates that the traffic has been growing at the rate of 5 per cent, per annum, and it is quite reasonable) to suppose that this rate of growth will continue;. Therefore, by 1928 there will be approximately 1,500,000 tons to be coped with in each direction. On the present line the average gross load of tons is 161 tons, on which basis by 1928 there would 1"' required at least thirty trains a day each way. The. position is even worse than this might indicate, because the trains, owing to traffic considerations, cannot be run at regular intervals. As long ago as 1914 the General Manager of Railways stated that the line was reaching the limit of its capacity. Naturally, the; position is very much worse to-elay. I do not think it is necessary to lay any stress on the question of danger clue to the heavy grades and excessive curvature, because, although a steep and crooke;el line is not as safe as a leve;l anel straight one, there are nevertheless many lines in New Zealand worse; than the line under review, and these are not considered dangerous ; but for the purposes of this report I consider that sufficient has been shown to indicate, that when comparing the financial results from various lines, the. e;e>sts in connection with a new line should not be compared with the; present line but with a double track on the present alignment. An examination of the grades existing on the lino from Wellington north to Marton, and also via the Manawatu Gorge to beyond Wooelville, shows that it wemld not be advisable to adopt a, grade much steeper than 1 in 100, and, as this grade would be on a practically straight line, its resistance to haulage would be approximately one-third of the present graele. Therefore, as far as investigations have gone in connection with possible deviations, it has been assumed that- a maximum graele of 1 in 100 would be adopted ; and in fact, owing to the large amount of tunnelling required, linos have se> far be;e;n located on the basis of not steeper than I in 120 in tunnel. The configuration of the; ground is such that a great deal eif difference in cost is not made; by a, modi-rate variation of the; grade' in either direction,