THE OTIRA TUNNEL.

BATTLE OF ROUTES

EARLY ENGINEERING

CANNIBAL. GORGE v. OTIRA

In view of the opening of the Otira Tunnel to-day the following extracts; from articles in tho Wellington Post' I of Thursday will be of interest: j ' Wherever there is a_ railway there" is i a route fight. Between 1874' and 1883 ' numerous surveys of proposed^ routes ! were made, and three routes stand out notably. Tnese -are the route now adopted, connecting the Lealey and the O.tira Valleys under Arthur's Pass; the Cannibal Gorge route, connecting the Amuri Plains with the Inangahua Valley at Reefton, via the Lewis Saddle; and the Hurunui Gorge route, from Waikare to Jackson's. Until the con-' (tract for the present route was actually j-let in 1907, people in. Reefton and some in Westporu agitated strongly for the Lewis Saddle route, while the Grey Viilley people stood . out for BealeyOtira. Harbour rivalry between Westport and Greymouth entered into this controversy. I The Bealey-Otira route received its first strong authoritative backing in 1883, when a Royal Commission reported in its favour. The later 'eighties and earlier 'nineties' saw the initiation and failure of the Midland Railway Company. In 1900 a committee of .engineers was set up to consider the best means of crossing the actual dividing range—whether to adhere to one of the original proposals (a 1 in 15 grade, with Fell centre-rail system, over the range1) or to have a long summit tunnel. The committee decided in.-. favour of a, summit tunnel about six miles long, with a grade of approximately 1 in 37. In 1902 Mr. V. G. Bogue, an eminent American engineer, was called in by the New Zealand Government, and, .after considerable investigation, he rei commended a line with a shorter summit tunnel on a grade of 1 in 32. As he considered that a line with a summittunnel of such a steep grade was quite suitable, further surveys were made; and a line with a summit-tunnel on a grade of 1, in 33, and in its present position, was finally located. This proposal was submitted to Mr. Bogue, who confirmed the recommendations of the local engineers, and it was finally decided to adopt this route. Mr. Bogue was assisted in his report by Mr. R. W. Holmes, who, later on, as Superintending Engineer and principal assistant to the then Engineer-in-Chief (Mr. P. S. Hay), took the chief part in preparing the specifications for' the tunnel contract. In April, 1907, Mr. Holmes succeeded Mr. Hay as Engineer-in-Chief, and on August 12 of th-at year the contract for driving the Otira tunnel was let to Messrs J. H. McLean and Sons for £599,794. The time for completion, was fixed at five years. The contractors be^an to drive

the bottom heading, at the Otira end, in April, 1908—on May sof that year the Prime Minister, Sir Joseph Ward, fired the first shot—but the work proved to be too great, in the circumstances, for private enterprise, and it was taken over by the Government before it was half completed, in December, 1912. The

contractors had driven 2 l-3rd miles, of which 1| mites was lined and completed. Over five years and a half elapsed before the operations, directed now by the Public Works Department, resulted in the bottom headings- meeting in July, 1918. By the middle of 1920 the tunnel was ready for the final stape, electrification, now completed by the English Electric Company. . Here are some of tho main points of, the Otira tunnel:

Length: 5 miles 545 yards. Height: 15 feet 6 inches. % - Width: At rail, 14 feet ; at widest point, 15 feet.

Grade: Uniformly. 1 in 33, dipping from east to west. ' Altitude: Eastern end, 2435 feet ; western end, 1585 feet; fall, 850 feet.'

The altitude of Arthur's Pass is about 3000 feet; that of Mount Cook's summit, 12,349 feet. The tunnel carries a single-track railway of 3ft. Gin. gauge, which is the standard gauge of the New Zealand Government railways. In cross-section the clear, height above the rail level is 15ft. Gin., with a maximum width,"of 15ft. POWERS EMPLOYED.

The primary powers first utilised at Otira and Beaiey w ere used for driving the tunnel. ° Mydrp-eieetrie jjower was generated . from Holt's Creek at the Otira end, j and from The Punch-Bowl at the Beaiey , end. The Puneh-iSowl was fairly equal I to the contract, but the effect of dry ! summers and mid-winter freezing on i Holt's Creek is so pronounced that an assistant steam station was set up at the Otira end, to keep the tunnel works going. It may be added that most of the excavation of the tunnel was done . from the Otira end, because that end is the lower o«ie, and the 1 in 23 dip of the tunnel made outward haulage easier, and allowed the water to now . out, whereas at the Bealey end the water had to be expelled by being pumped up the grade. Later on came the question of what tractive power to use for the railway service, and how to generate it. Length of the tunnel and its grade .necessitated electrical traction. But the power need.cd was far in excess of the hydro--1 electric possibilities of Holt's Creek and the Punch-Bowl. Therefore the plant generating electrical power in the new power-house afc Otira is driven by coal and steam. To say that is not to say that hydroelectrical power will never supply the tractive effort. According to an official publication, "in the future, Avhen,power becomes available, it is intended to link up the line with the hydro-electric system,- and to use the steam plant as a stand-by.'' NEW OTIRA TOWNSHIP. The station buildings at Otira, of the type familiar to New Zealanders, are situated on an island platform, and are large and well-appointed. An. electrie-a!ly-lit subway gives access to the plat, form, thus dispensing with an overhead bridge. • ' . A township of 50 houses has sprung up to /accommodate the workers to be permanently employed in connection with the operating of the tunnel. The houses are of the bungalow type, fitted with electric light and all conveniences, and bear no resemblance to the usual railway house'of monotonous design and colour. Each is located on a quarteracre section, on either side of a wide central roadway. A neat building is the hostel erected for waitresses ■ employed at the refreshment rooms. At Arthur's Pass station, on the Canterbury side, more workers' houses have been built, and are connected with, drainage iind water supply, similar to those at Otira. Passengers making the overland journey will now secure lunch at Otira instead of at Arthur's Pass, as formerly. The new rooms at Otira are among the finest in the Dominion, being designed with a view to comfort and efficiency. PROGRESS TOLD IN DATES.

The driving of the Otira tunnel was hegan by private contractors m May, Iyuß, and was taken over by the Government in December, 1912. On May 7, 1918, trie men at the Bealey end of the tunnel heard the tiring of the explosives *"• used at the Otira end

- On July 20, 191S, the bottom headings of tne tunnel met —3 miles 68 chains 10 links having been driven on the up-grade from the Otira end, and 1 mile 37 chains 44 links on the downgrade from the Bealey end. The eleetrirication contr>i;ct was let to the English Electric Company in 'August, 192U, at about £350,000. ■Official''opening date of completed work, August 4, 1923. On August Cls, 1920. the New Zealand Government arranged a contract : with .the English Electric Company for electrification, the price bein<j approximately £350jOCK).' The contract, included the.electrification of 13 miles of track, as follows: Tunnel, 5\ miles; from Otira- end of tunnel to Otiira station, 3 miles;-station sidings at both ends, 5 miles. £ ivT!he'contract," writes a contributor, <:also included the electrical equipment of a .coal-a nd-steam "generating station of 4000 horse-power capacity at Otira; | the sup],' 1./ of six eiectric locomotives (which will draw the ordinary rolling stock of the Government railways) ; the electric lighting of the tunnel; and the equipment of the necessary at Otira. Otira is the headquarters township of the electrified line, Arthur's Pass station (on the Bealey side) being secondary so far as the control of the tunnel is concerned. OTIItA ffOWER-HOUSE.

j "All the important departments, ' power-house, locomotives, batteries, signalling ul-a-nt, etc., are located at Otira, and C'aiiterbury people and those from other parts ot the Dominion who see the West Coast township for the first time are in tor a surprise. The at- . tention of visitors to Otira is first held Iby the imposing, power-house, a very ' fine structure wjt-h modern equipment. j Two steam turbines of 2000' hqrse- ■ power, 160 steam pressure, 29-inch i vacuum, and 3000 revolutions per mm!- -! ute are geur-ed down by a. double helii cal single reduction gear, to drive the j generator o£ 1200 kilowatts and 1650 j volts at a. speed of 450 revolutions per 'minute. There are three marine type j Babeock and "Wilcox boilers with induced draught fans. "The Otira tunnel is the first section of railway to-bS electrified in New Zea- | land, and therefore jjossesses additional j. importance from the viewpoint of progress. Each main, line locomotive, j weighing. 50 tons, is of 680 horse-power, I operated at 1500 volts. Freight trains • will be drawn by two locomotives and passenger trains by one. "The electric signal system at Otira is the very latest idea, and is similar to that used on the London tubes. The claim is made for the Otira system that it absolutely prevents accidents." -.- The electric train will probably take less than twenty minutes to- go through the Si-mile tunnel.

IMPORTANT BRAKING. From another sourse, an article in "Board and Council," it is gathered that the main line electric locomotives, each weighing 50 tons, are constructed to run at 18 miles an hour on-the upgradient (1 in 33) with a fully-loaded train. The resistances are designed to limit, the speed .on the down gradient to '2Q miles an hour when two locomotives are holding a passenger train of 200 tons. On a gradient of :1 in 33, brake gear must be absolutely reliable, I and "the locomotives are, therefore, fitted with four brakes —the rheostatic brake, the Westinghouse automatic air 1 brake, the Westinghouse straight air brake and the hand brake. "The rheostatic brake was adopted in preference to the regenerative - brake, because .th« powerhouse supplies the railway'load only, and therefore there! would be occasions when there would be j no load to absorb the regenerated energy/: The rheostatic brake also renders the 'locomotive independent of the trolly voltage. The locomotives are fitted with hand-operated and air-operated sanding'gear. A large standby battery is carried to. provide energy for the control gear and'compressor motor at 120 volts. Its capacity is sufficient "to enable the locomotive to make a complete-

round trip. Ir, the event of tins 1500 supply failing,' the battery supply enables the driver to use the liieoatatic brake as well as the air brake, and this furnishes an additional factor ot surety." i At present only five main line locomotives are required, but it is anticipated that as the traffic increases ■ eight main line locomotives will eventually be required for the working ot the electrified line. THE PANTAGIIAPHS. The locomotive lias four D X motors ' each of wlucli develops i,Oh.p. at the' jUead or .the wheel at one-hour ratine j In© corresponding speed at 15CX> line j volts ls 18 miles per hour. The motors I are wound fcr 7U>-volts, and are con- | nocted in permanent series. The tractive ; eftort is 14,20U1b at the one-hour ratI o^: i +'j iJle , :uconiotive bogies are | articulated, so that none of the tractive jiorce ot the moLor is taken through tne underri-ame, an important provision niien it i 5 iwueinbered that the ferae- ! tn-e force will be considerable when the trams are double-he.ided." IMPROVING WEAK LINKS. \^^°S t["n that, the South Isla»d Coast) fuias itsejf in with regard to Otira tunnel may b^comoared witu Uie problem that. Ainu,.can 'railway "0^ panics have found ,„ . their R oci£ y fountain crossings. Mr ji,van tariy^ the wek-Knovvn n } dro-e.ectric enginee/to the >,evv Zealand Govenuneut and who is now of the English fclectrie Company (contractor for^the Othi tunthi Ch^^W* ha* P°luted °M that the Chicago, Milwaukee and St Paul Railway Company found that the liocky J^T" } mpF ed a Seveie «strictioZ upon the trattic-cai-ryinjr and earaincapacity of the whole of this company's system from Seattle to Chicago Itthough the mountain division t' but siioit 111 proportion to the whole The company applied electric working to the '»?)%& foanf? ln division, a distance of :J''ft wh»ch has enabled the companj to double its traffic not only on the mountain divison, but throughout the system. i n the words of the presitht °f lcilUs have "forgotten'^thaV the Rocky Mo.vntains exist in regard to their influence on the traffic. llie Otira tunnel crosisng of the\TiT\ AIP4 lH' eT lt, s a sin"lar FP-ob! on\t ir en Government on the Midland Railway. , The mountain division is only short- but the capacity of a bottle, in influx and ef! mix a -S the capacity of its narrowest part, just as the greatest strength of ln + ?S mJ ts We^ est iink- Where, as at Utira, tne grade is too severe for a steam locomotive to work to the b-st advantage and where a limit is thus placed on the movement of traffic, the electrifying "or a comparatively short Tt lOnf T J t^ c the canyiiig capacity of the whole of the railway. WEAK LINKS NEARER HOME

Mr Parry writes: "Mountain divisions generally present very favourable conditions for electric traction, as steam locomotives reach the limit of their capacity very quickly on grade, ana impose limitations on the movement of traffic. It has been proven that the application of electricity to haulage on sections where the grades are severe increases the. carry ing capacity of that section from two to three "times the maximum capacity possible with steam haulage, according to the nature of the grades and the number of tunnels, etc. . . . The same reasoning applies to the division from Springfield to Jackson's, on the Midland Railway from Taumarimui to Waimarino on the North ■Island Main Trunk, and in a lesser degree to the section Ua-,veen Wellington anrd Paekakariki. In these eases the traffic-earning capacity of the whole system, of which tney i:o,rm a part, is substantially increased at the cost of electrifying a, portion only where the gradients arc severe."

Note carefully Mr Parry's words: "From Springfield'to Jackson's on the Midland Knihvay." Tlie present electri-rk-ation from Otira to Arthur's' Pass "station is only a portion of Springfield to Jackson's; the" latter comprises the whole mountain section, 62 miles, whereas the length of the present electrified section i& only 8 miles (plus 5 miles' of sidings). But- Mr Parry says . that the greater application 'is the ■logical ■■ outcome- of the smaller one. When Mr ParrY,, then acting for the New Zealand Government, went into this electrification question, he prepared particulars covering the whole mountain "section ; but, he adds, "it was decided finally to'limit the application of electric, working to the Otka-Ar-thur's Pass section as- a first instalment, as it was desirable to keep down I capital expenditure, and, furthermore, whilst several local sources of power were available which were adequate to the needs of t'jp Otira-Arthurs Pass section, the electrification of the whole line depended upon an extension-pivthe Lake Coleridge powe,r'.plant. Besides this, inasmuch as electric working on the Is'ew Zealand railways- is rather of \an experiment, it was. a" good principle Ito experiment on a sjnall scale, and ttt& familiarise and. to educate a trained i staff of c ectric workers." i

SAVING BLACK DIAMONDS. If strict iy economic reasons alone governed the question of applying e;ecti'icity to railways, its.application might belimited to suburban lines and mountain divisions and tunnels, where it. is needed to get adcljtionat traffic through. .But somer.imes strategic reasons infiur jence the rnpnostion of electricity; and sometimes the desire to conserve coal fuel (a wasting asset) operates. On this point Mr Parity writes.—

"Tliere is another reason for electrification of railways which has a.natiorial aspect, by the saving in coal, which seems more difficult to get as time goes on. Taking the division of the Springfield to Jackson's as an examp'e, it would require- 11,<X)O to ,12.000 tons of coal per annum to maintain by steam locomotive the service specified—viz.-, 1000 tons per day ftro-m west- to east, 700 tons per day from east to west, together with one passenger train each way per day. This coal has to be hauled backward and forward, up" and down steep gradients, at a cost of a further quantity of coal, and additional rolling stock has to he provided.•"'

Uniike the black diamonds, the 'white diamonds"; transport themselves and are inexhaustible. Nor do the na-turally-replenjshed water supplies go on strike.