ROAD TUNNEL TO LYTTELTON

Press, Volume XCVIII, Issue 28795, 16 January 1959, Page 8

ROAD TUNNEL TO LYTTELTON

Authority Approves Plans

Plans and specifications for the construction of the Christchurch-Lyttelton road tunnel, the reading and associated works near each portal and for the ventilation buildings and their equipping were approved yesterday by the Road Tunnel Authority,

perfect job,” was quoted as the opinion of , the City Engineer (Mr E., Somers) ou the work of the engineering consultants, the Ministry of Works.

The approval of the plans, which will now go forward to local authorities for their formal endorsement, was described as a milestone in the progress towards the building of the tunnel. Estimates of costs are expected to be available by the end of this month and application will then be made for consent to a loan. Tenders for the contract will be called immediately the loan proposals are approved. The tunnel will be 6500 feet long and 28 feet wide.

JThe National Roads Board ad vised that. .it had agreed in' prin ciple to construct the approacl road from Ferry road-to the tun nel toll plaza, to standards to b< approved by the board and fit in with the construction pro gramme when the Authority ha( established the practicability o financing the whole tunnel scheme The board will not assume res possibility for any part of thi tunnel construction or roadway paving. An earlier estimate was that th< cost of the approach road ant bridges would be £320,000. Mr W. P. Glue: Does that meai

that the Roads Board will take responsibility for acquiring the necessary land? “Yes—l thihk so,” replied the chairman (Mr W. S. Mac Gibbon). Side-road Access

When the plans and specifications for the tunnel were discussed, Mr L. G. Amos asked if provision was made for a side access road from the Heathcote portal to Humphrey’s Drive to give an outlet to the north of the city. Mr Mac Gibbon: It is not on the plans. It is a matter for a separate contract. The documents had been submitted for perusal to Mr Somers, who was on the advisory engineering panel, said the chairman. Mr Somers had described them as “a perfect job, involving a tremendous amount of paper work.” Mr Amos: When do you estimate we will be able to call for tenders? Mr Mac Gibbon: Immediately we get the loan authority. The City Council was not vitally interested in the plans at the moment but it was necessary that the plans should be submitted to it and also the Heathcote County Council, said Mr Mac Gibbon. As a courtesy, they would also be submitted to the Lyttelton Borough Council. Use of Spoil The specifications provide that the material excavated from the approach cutting and' the fanhouse access at the Heathcote end of the tunnel be placed in approach road fillings. Spoil taken from the north end of the tunnel will be deposited for the construction of fillings on the ap-

proach road. The contractor will be responsible for the removal and disposal of nine houses at the Lyttelton end.

The road work under the contract includes the main approach road to the tunnel entrance and access to the fan house at the

I- north end. At the Lyttelton end it i. includes the deviation road from h Tlcehurst road to Jackson road, access to the fan house and the l “ raising of a lower end of Jacke sons road to provide a turning o area for traffic. >_ Both fan houses will have an d area, of about 2800 square feet. They v*Hl be of reinforced con- » Crete portal frame construction, £ with a corrugated aluminium roof e oh timbered purlins. One wall y of each will be glazed with fixed louvres. The floors will be e plastered and the exterior wall d finish will be of concrete slabs. The equipment entrances will n have folding steel doors.

Geological Report According to the geological report by Mr H. E. Fyfe, flows of water comparable with those experienced in driving the railway tunnel are likely to be

encountered. All the prospecting carried out at the site of the lieathcote portal indicated that rock would be encountered within a few feet of the portal, reported Mr Fyfe. The ground might be heavy for three chains or so until there was sufficient cover to make the rock self-supporting. For roughly a chain and a half from the Lyttelton portal, the ground was likely to consist of loes. possibly grading into slope debris consisting of tumbled volcanic rock, ranging from small fragments to blocks three feet or rtlpre through. It would appear, said Mr Fyfe, that heavy timbering might be necessary for a few chains at the Heathcote end.