D.—l

116

Assuming that no portion of the line now finished up to Otira Station, at Goat Greek, will be abandoned, the alternatives to the Fell line are : (a) to construct a switchback line from a point a short distance above Otira Station to meet the l-in-50 line surveyed in 1883, then to follow this line to the Bealey; (b) to cross the Otira below Goat Creek, and locate a line on any grade deemed best (say, 1 in 40 to 1 in 50) by doubling about on the slopes of the Otira and Eolleston Valleys until a sufficient height has been attained to enable the dividing range to be pierced by a tunnel of any desired length, or without a tunnel at all; or (c) to run a line by the shortest route from Otira Station to a point on the left bank of the Bealey Eiver near the 3-mile peg of the present working survey, and pierce the range by a tunnel about 6-J miles long. By abandoning a portion of the constructed line down to near Kelly's Creek several other schemes for an adhesion line could be formulated. (a.) The first line would be about miles long, between 6 m. 67 eh., Otira, and the 3-mile peg in the Bealey Valley. The probable cost would be, say, £550,000. As it would be located on some of the worst slopes in the Otira and Eolleston Valleys, and would be more costly to work than the l-in-50 line given in the table attached, it is not necessary to discuss its merits at any length. (b.) It would be possible to get a line with any grade between 1 in 40 and 1 in 60 by crossing the Otira below the junction of Goat Creek and laying out suitable lengths of grades on the hillsides. The chief characteristics of several lines with grades of lin 40, of a line with lin 44, one with l-in-50 grade, and one with l-in-60 grade are given in the attached table, from which it would appear that the best line of the group would be the l-hr-40 line with the shortest length of about 8-6 miles. On all these lines, except the l-in-40 grade, B'6 miles long, the maintenance would be considerable, on account of the length of line that must be located on, very steep hillsides ; also there would be some risk of injury to trains from loose rocks being set in motion on the steep slopes during frosts and the other severe weather conditions which obtain at Arthur's Pass, and there would be some difficulty experienced in constructing simultaneously sections of railway one above another in such steep country. On all these lines, except the short lin 40, there would be an excessive amount of curvature, as compared with the alternative (c), which curvature would cost a considerable yearly sum for wear and tear. The cost of construction might be slightly reduced in each case by the use of switchbacks, to the use of which, when there is an engine at each end of the train, there are no serious objections. (c.) The third alternative is to run the shortest possible line on a uniform grade on the straights between the 6m. 67 eh., Otira, to a point on the left bank of the Bealey about 7ch. above the 3-mile peg. The grade so obtainable would be about lin37or 1 in 37f on the straights, with proportionally flatter grades on the few curves required. The line would cross the Otira below Goat Creek, its length would be, approximately, 8-3 miles, and the tunnel would be about 6m. 10 eh. long. The cost of construction would be about £500,000 if a tunnel of the standard section of New Zealand railways were used, which would be sufficiently large if electric locomotives were employed to work the Otira-Bealey section; but £545,000 if the tunnel were made, say, 2 ft. higher and 2 ft. wider, to allow for better ventilation if steam locomotives, burning either coal or liquid fuel, were employed. The maintenance on this line should be much less than on any of the lines on the hillsides, the two miles of its length in the open being located on the most favourable part of the Otira Valley. It is also by far the safest working line that could be constructed over the pass. As it therefore appears that the best alternatives for an adhesion line necessitate the construction of a long tunnel, it is necessary to discuss somewhat fully the possibility of the quick construction of a long tunnel at Arthur's Pass, and the possibility of its being successfully worked when completed. For quick construction it would be imperative to employ rock-drills, worked either by electricity or compressed air; also to use electric or compressed-air locomotives for haulage of the excavated and lining materials, and to provide a sufficient pumping-plant to enable the tunnel to be driven down grade from the Bealey end. The pumps would be set at suitable intervals in the tunnel, and be driven by electricity or compressed air. It would be necessary to supply effective artificial ventilation. To provide the necessary plant, boilers, engines, electric or compressed-air machinery, drills, pumps, tools, ventilating-fans and tubes, water-services, electric conductors, &c, offices, quarters for staff and workmen, workshops, locomotives, wagons, sheds, &c, a sum of, say, £56,000 would be required for the longest tunnel, and a somewhat, but not much, smaller sum for the shorter tunnels. The shorter tunnels would, however, involve extra cost for service approach roads, and plant for the haulage of materials. This estimate is on the assumption that steampower would be used; and, if this were so, the power-station would be located at Dyer's, and the necessary power transmitted to the Bealey end by high-tension electricity, if the line could be finished to that point in time, so as to enable coal to be run right up to the power-house; if not, the power-station would have to be located at Otira Station below Goat Creek, and the power would be transmitted to both ends of the tunnel by high-tension electricity, and this probably implies the use of electricity for the transmission of power to the various working-stations in the tunnel. To insure that work would be carried on continuously throughout the year it would be necessary to use steam to generate the electric-power. As the flow of water in the Otira practically fails in times of frost, and as also the works for supply would be liable to be carried away or be damaged during floods, it is not at all certain that work at the Otira end of a tunnel could be carried on continuously by water-power. More water appears to be available in the Bealey watershed, but as much more power would be required at the Bealey end it is also uncertain whether works at that end could be carried on continuously by water-power. Had a sufficient supply of water been available it would probably be found that compressed air would be preferable to electricity for