D.—l

80

Tramways. The tramways will always remain a most important load. Their present consumption of power is as follows :—

Allowing for the probable increase, these figures for 1915 may be estimated as follows : —

The maximum tramway load is estimated at three times the average load. Occasional " kicks " may exceed this limit for a few minutes. These would either be dealt with by storage batteries nstalled in Dunedin, Christchurch. and Auckland, or otherwise would be easily carried for a few minutes by the overload capacity of the plant. The growth in traffic has been estimated well on the conservative side—namely, only 15 per cent, in five years. The basis cost taken in estimating the above revenue is fd. per unit, and at this price it will pay the tramways well to take high-tension current in bulk for conversion to direct current rather than to put in fresh plant to supply it. In Dunedin for the year ending March, 1909, the water-power plant supplied 2,158,696 units to the tramways, for which they charged £6,883, or 0-767 d. per unit. This yielded, no conversion, 1,664,372 units, which thus cost 0-98 d. per unit and showed an over-all efficiency of conversion of 77 per cent. It might be necessary, in order to induce the present steam tramway power plants to shut down altogether, to offer the power at slightly lower rates—say, 0-6 d. to 0-7 d. per unit— but it must be noted that in Dunedin it pays the tramways to take high-tension current for conversion at 0-767, although they have a reserve steam plant installed, and, when the other tramway authorities definitely shut down their steam plants, they will save not only the working-expenses, but the depreciation charges on them as well. It will be necessary, of course, to continue paying interest and sinking fund on the reserve steam plant until its cost is finally redeemed, but it is obviously unnecessary to maintain a depreciation fund on such plant, and the depreciation reserve already accrued on it may be egitimatelv used to purchase the necessary converter plant. Other steady demands for power include pumping for water-supply and sewerage, harbour and dockrequirements, and railway workshops in each centre. The present power-installations and estimated ioad-factors for these purposes in each of the centres are as follows : —

A basis price of 0-66 d. per unit may be taken for pumping, with its high load-factor, and Id. per unit for harbour and railway workshops consumption, with their lower load-factors. These compare very favourably with the costs now obtaining under the existing conditions. The latter is, for instance, about one-half of the present power-cost in the railway workshops. Or. again, the works costs of power-production in Wellington for pumping from the tramway power-station is 0-795 d., and

Cost III Passengers Car-miles Units used Power | per Annum, j per Annum. per Annum, (working-costs only). I __J Plant- Load capacity. factor. Wellington Auckland Christchurch Dunedin £ 21,932,000 2,203,666 4.418,595 16,998 •28.736.000 2,401,580 6,386,082 12,676,000 1,584,522 2,654,285 8,914 11,445,000 1,108,212 2,153,000 6,762 K.w. 3.000 19-4 2.100 34-8 1,500 20-2 1.000 24-6 i

I Passengers Car-miles Units used per Annum. per Annum, per Annum. Animal . Maximum Revenue . e ? e Demand i . Wellington tuckland !hristchurch )unedin 25,100,000 2,540,000 6,100,000 32,500,000 2,760,000 7,350,000 14,500,000 1,820,000 3,050,000 13,500,000 1,280,000 2,500,000 £ 19,000 700 2,100 23,000 840 2,525 9,500 350 1,050 7,800 285 860

Wellington. Auckland. Christchurch. Dunedin. Water-supply and sewerage h.p. Estimated load-factor Harbour and dock power h.p. .. Estimated load-factor Railway workshops h.p. Estimated load-factor 1,000 50 560 30 120 25 660 450 50 40 260 500 30 30 80 440 25 25 j |_ 300 50 460 30 240 25