THE ROUNDELL ROUTE FOR THE RAILWAY.

Nelson Evening Mail, Volume XIV, Issue 290, 18 December 1879, Page 2

THE ROUNDELL ROUTE FOR THE RAILWAY.

MEMO BY MR BLAIR, C.E. The following letter has been addressed by Mr Blair to Mr Acton Adams and the Nelson members of the House of Representatives : — Dear Sirs — With reference to our several conversations on the subject, and my subse quent promise to Mr Shephard, I beg to submit the following memoranda of the leading points of comparison between the various routes that have been suggested for the railway between Foxhill and the Buller Valley, and the reasons that lead to a decision in favor of the one by Blue Glen and the Roundell. As you are aware, the principal element in determining the carrying capacity of a rail way is the gradients. Heavy loads cannot be pulled up steep gradients without heavy locomotives, and heavy locomotives must have heavy rails with an expensive line to run cm. Under ordinary circumstances the limit of steepness ought to be about 1 in 50; tho usual type of locomotive will draw a fair load up this gradient without an undue waste of power on the easier ones; it being utterly impossible to get anythiug approachiny a level line for any distance in any part of New Zealand. The ruling gradient on the Hope route is 1 in 33, that on the Blue Glen route 1 in 50; the locomotive that will pull 100 tons on the latter will pull less than 70 on the former. The advantages are therefore immensely in favor of the Blue Glen line. You have already some experience of the evils of steep gradients on the Nelson and Foxbill railway; those on the Hope line would be considerably worse than this, and it is practically impossible to reduce them to the workable limit of I in 50 above referred to. So far as distance is concerned the Hope line has the advantage by 10 miles, and probably the cost will also be somewhat less, but the difference in the latter particular is too small to be worth considering, and if we take the coat in proportion to the relative carrying capacities of the lines the balance will be greatly in favor of the Blue Glen route. With reference to the amount of tunnelling required there is practically no difference between the two routes now under comparison. As to the accommodation afforded to the country generally, this is a matter on which you are probably better able to judge than I am. So far as my opinion is worth anything I think the lines are about equal. The Blue Glen line misses the Motueka Valley, which is accommodated by the Hope one; but the latter misses the traffic from the interior by To|> House, which is intercepted by the former. Altogether I have no hesitation in saying that there i 3no comparison between the Hope and Blue Glen routes. The latter is infinitely the better of the two, and inconsequence of its flatter gradients the balance would still be on the same side, even if it were very much longer aud more expensive. Having compared the two main routes, I shall now compare the Blue Glen route and an alternative thereto which haa been proposed going through the Spooner Range by Rochfoot's line, but with 1 in 50 grades, then following up the Motupiko Valley to a junction with the Blue Glen line in the Big Bu9h. The object of this line would be to accommodate the Motueka Valley settlers without necessitating the heavy gradients of the Hope Saddle, These advantages are not, however, commensurate with the extra length of line and heavy outlay involved. The line will be 9 miles longer than the Blue Glen one, and will cost at least £240,000 more ; the tunnel through the Spooner Range being 202 chains (2J miles) long— nearly a mile longer than the Lyttelton tunnel — the longest in the colony. Another line was proposed through the Spaoner Range by way of Pretty Bridge Creek and Brown's Gully. This route was strongly advocated by some of the Motueka Valley settlers, and pressed on the attention of the Minister of Public Works by yourselves. From an inspection of the ground I knew that it was quite impracticable, but, out of deference to your wishes, I had some levels taken. These ahow that with 1 in 50 grades it would be necessary to have a tunnel of 210 chains (2-J- miles) through the main range, and one of 36 chains (nearly £ a mile) through a subsidiary spur. The latter might be avoided by running up the Motueka Valley about a mile, and doubling back to the confluence of the Motupiko, but this would be worse than the second tunnel Even with grades of 1 in 35, as on Rochfort's , line, it would require 100 chains (1^ miles) of tunnelling at the Spooner Range. Altogether, the Pretty Bridge route ia the most objectionable of the lot, and the idea of bringing a railway in that direction is quite out of the question. In addition to the three above-named, several other routes through the Spooner Range have been examined, but. none of them bear comparison with tha "Blue Glen 1 one ; Unless we commence far back on the Foxhill line and go round the coast, there is no way of getting through the range without heavy tunnelling. This is in consequence of the lines coming square at the range, where there is no suitable ground in which to run np a gradient. In the case of the Blue Glen route, the range is parallel with the lines, consequently the whole length i 3 available for running up a gradient. There is no saddle in the Spooner Range less than 1,200 feet high till within four miles of the sea, where there is a drop of 250 feet. I may add that, with the exception of a tunnel 55 chains long between the Motueka and Motupiko -watershed , the works on the route are comparatively easy, and a very good line cau be got. I am, &c, W. W. Blaik.