MAIN TRUNK TUNNEL

Evening Post, Volume CVI, Issue 56, 4 September 1923, Page 7

MAIN TRUNK TUNNEL

LONGER v. SHORTER

KAIWARRA AND NGAHAURANGA ROUTES

AVOID CONGESTION ON EUTT ROAD. -:

(By "Wellingtonian.")

In this article it is suggested that a main trunk railway route that avoids the Hutt road as much as possible, by tunnelling through; at Kaiwarra, instead of at Ngaliaiira-" nga, may save the cost of the -longer tunnel by cutting out the cost of reclamation (and probably quadrupli--. cation of lines) on the Hutt road. Ihe Hutt road will become a bottleneck soon enough without adding to its railway burden, even in part.

The new route out of Wellington of th« North Island Main Trunk railway'is a matter of pressing importance. Accepted notions about it are not necessarily correct notions. / ". '."t".',

There is about twenty miles-of-more or less level railway between'^Wellington Vnew railway station site and" .Upper Hutt. At various places along this railway a branching-ofi point might bo selected,, from which the intervening hills could be pierced by a railway tunnel to the west coast. The nearest point to Wellington City, on the Hutt side/ is Kaiwarra; the farthest, point is Akatarawa. On the west side, the nearest point is somewhere above Tawa Flat ; the farthest is, I suppose, Reikorangi. v A big factor is • the length and cost 6f the tunnel. But there are other factors beside. One of these is the advantage that accrues to. any. route that lies as little as possible along the line of the existing Wellington-Upper- HnttWairarapa railway. -'_- The nearer to Wellington the branch-mg-off point of the Main Trunk line is located, the less the congestion on the narrow Hutt road. From this point of view, a Kaiwarra tunnel would come first. " . . ■ <:-;

HUTT BOTTLE-NECK.

A Ngahautanga tunnel, which everybody speaks of, would, as " The Post" has pointed out, create something of a, bottle-neck between Kaiwarra, and Ngahauranga. This congestion would be prolonged, as far as the Hutt road is concerned, by a Korokoro tunnel route. And a Main Trunk route by Akatarawaj/ or by one of the intervening valleys, would intensify the problem, and would bring into the question that section of single line railway connecting Belmont and Hayward's, which. Mr. Coleman Phillips says is unstable through liver action. - If all the railway traffic-in audout of-; Wellington Jiad to be dragged on one route as far as Upper Hutt, or even asfar as ■ Ngahaurnnga, a certain" penalty' would have to be paid in congestion, orelse in quadrupling the railway line, andreclaiming from the sea. ':''- That expensive item would be eliminated—for a long time, at any-irate—*: it the Main Trunk Railway 1, on issuing from the new Wellington railway station,.. were to strike out for itself an independent route, Tising along .the"hill-side,^ and tunnelling into the lull at a point above and perhaps a little beyond Kaiwavra. _The saving in the'cost of'quadruphcation'ahd reclamation could be usedto off-set the coet of a longer tunneHrom Kaiwarra to the Tawa Flat side, as compared with a,shorter tunnel fr6m Nga--; hauranga to Tawa Flat. ....

I am not prepared to estimate the cost of meeting the congestion if the Mairi Trunk traffic were dragged wholly or partly along the Hutt road. But eyenthe partial use of the Hutt road-(as:in-volved in the Ngahauranga tunnel schema) • would be very costly in the way of reconstruction. Consider the sea-wall alone. s.'. •'."." ""■, SEA-WALL COST AND BISKS.- - The reclamation and duplication work carried out by the Department of Railways, about twenty years ago, was7.both\' slow and expensive. For a long time after it was completed the sea frequent--ly breached the wall, and only lately," after much repairing, has it become sufficiently established to stand satisfactor-* ily. ..Reclamation means that, a great length of existing wall .will have .to be* lost, and the Government will be faced again with heavy initial expenditure andrecurring maintenance charges, until at" last a stable condition is attained. ' Nor am I prepared to estimate JluiT cost of the larger tunnel from Kaiwarr&r to Tawa Flat. . ' •.. "iV: . But I am certain that what is.■.■■, . saved in Hutt road expenditure by a- ■ Kaiwarra tunnel route will offset (or .". . »11 but offset) the greater length arid". v '_. cost of a Kaiwarra tunnel as com»"°: pared with a Ngahauranga tunnel. The case I present is one that has it* appeal to the engineer. Still more does it appeal to a. person with imagination— which Cove says is stronger than".Svilll *.„ Go up in an imaginary aeroplane-and-look.down at this wonderfully walled-off city. Nature's ramparts separate. it..' from the'Manawatu and Wairarapa hinterlands. A narrow ledge between the hills and the harbour is the sole connecting link between the city and its main suburban outlet (the Hutt Valley), and beyond that the Wairarapa. At present the Main Trunk and Manawatu railway traffic hardly touches the Hutt Toad, except to cross it. Anything that: adds that traffic to the Hutt road congest* the already inadequate ledge which, has: been •painfully carved out and built up; partly at the expense of the hills,,partly by toll upon;the harbour space. „:. . :■ ■ '

A ONE-OUTLET CAPITAL CYIY.

Without, any. addition" to its railway burden, the shelf along the harbour shore will become inadequate for. its traffic soon enough. The man in the aeroplane wonders how, even now, it serves the inlet and outlet needs of a capital city and a great port. From; other cities ne sees broad roads radiating out to meet each, of the four winds. In Wellington he sees no relief save by means of a new higher-level Hutt road or mor« pushing back of the harbour. Both- of which will be needed soon enough. But let us not hasten the need by adding,to; the Hutt road's congestion at a, time when the great power of the rural interest in Parliament is pressing for backblocks development, and when every movement in the way of urban improvement k viewed with suspicion, even though the terminal and port facilities of railways are as important a part of the transport system of Cow Flat as is the local flag station. '

Anyone who cannot look ahead far enough to see the need of two independent railway outlets for Wellington, in order that through traffic as well as immense pending suburban development may proceed on business lines, is ignorant of arithmetical progression,, besides being destitute of that imagination connoted by the eternal truth of the city's motto, Suprema a Situ.

The site is indeed-supreme, and'the barrier of lulls was imposed by Nature merely as a tost for people's intcllicence and imagination. The .solution of the problem can only be adva&ed ;it principle that two ways out are h&tJL .than oa^aiui that, V^^|^

I>oses, the barrier Bhould lie pierced at its nearest practicable point. ' The last thing that is in the writer's mind- is to give advice to the Public Works Department, or to attempt .to ehowLthe Department its business. He is prepared to believe that the Department.haa already advanced in the direction pointed in this article. The purpose of hi(j;article is to contribute to the public opinion that is now being formed on «o vital a question.