Alice makes progress un­der­ground

Auckland City Harbour News - - NEWS - By KARINA ABADIA

The bor­ing ma­chine re­spon­si­ble for Auck­land’s Water­view tun­nels has bur­rowed un­der­ground on the first part of its two-year re­turn trip from Owairaka to Water­view.

Known as Alice, the 2200-tonne ma­chine has so far chewed through 12 me­tres of soil. The first of the 2414 re­in­forced con­crete rings that will line the two tun­nels have been in­stalled.

NZ Trans­port Agency high­ways man­ager for Auck­land Tommy Parker says it’s a bal­anc­ing act.

‘‘It’s been im­por­tant to tem­per the ma­chine’s enor­mous power to pre­vent her from dam­ag­ing tem­po­rary sup­port struc­tures as she en­tered the ground.’’

The ma­chine stops work ev­ery two me­tres to lift the con­crete tun­nel lin­ing rings into po­si­tion. Each com­pleted ring is then grouted into place.

Mr Parker says Alice is bor­ing at 40mm per minute com­pared with her top speed of 80mm but will work at a faster pace when more lin­ing rings are in­stalled.

A con­veyor sys­tem will re­move about 800,000 cu­bic me­tres of ex­ca­vated ma­te­rial from the tun­nels and take it to a build­ing al­most one kilo­me­tre from the tun­nel por­tal. From there it will be taken to a dis­used quarry which is be­ing re­ha­bil­i­tated for in­dus­trial de­vel­op­ment.

Alice op­er­ates 24 hours a day with crews of about 20 peo­ple and at least as many oth­ers work­ing in sup­port of the tun­nelling op­er­a­tions. Tun­nelling will be put on hold for sev­eral weeks in the new year to pre­pare for the con­struc­tion of a ven­ti­la­tion shaft build­ing at the south­ern por­tal. The tun­nels are due to open in early 2017.

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