Akin to a giant jigsaw, a transport project made up of interlinking and diverse parts is being constructed in Auckland. Richard Silcock reports.
Known as the Northern Corridor Improvements (NCI) programme this transport package will, when completed in four years’ time, extend SH18, provide additional busway facilities, introduce a dedicated route for both cyclists and pedestrians and provide new amenities for a number of sporting codes.
At a cost of $700 million it will include widening a four kilometre section of SH1, connect SH1 and SH18 (Upper Harbour Highway) with a new section of highway, and upgrade two kilometres of the existing SH18.
This will open up a more continuous route for travellers heading to and from SH16 and SH20 (Western Ring Route) and beyond to SH20A and Auckland International Airport to the south.
Fulton Hogan and HEB Construction, together with WSP-Opus and Jacobs as the design consultants, are the NCI alliance partners, having been awarded the project in June last year by the NZ Transport Agency under a Hybrid Competitive Alliance model where the agency stipulated a price threshold prior to tender.
Preparation works and construction started earlier this year.
While the transport agency is the client, Auckland City, Auckland Transport, Watercare, North Harbour Hockey Trust, North Harbour BMX and the Wainoni Park Equestrian Trust also have project involvement.
Alliance project manager, Andrew Johnson says they were awarded the project on the basis of providing a solution that is conceptually customer focussed and meets the Transport Agency’s current concentration on safer roads, more public transport facilities including cycleways and pedestrian pathways, and on their ability to provide the relevant skills and methodology.
“It was not a contest in cutting margins and offering the lowest price, but addressing the customer and client needs in a way that provides for the future growth of the area and the travelling public,” he says.
“Due to the alignment of the new section of highway we also addressed the relocation of several sporting facilities as that is an integral part of the whole project. These include a BMX track, an equestrian training facility, and a new $50 million hockey facility – all of which are contained in the project cost.
“To enable the SH18 component to proceed most of the physical works so far have centred on relocating and building the new sporting facilities.
“The BMX track is almost complete and we are well underway with site works and building the new clubrooms for the new North Harbour Hockey facility at Rosedale Park, which will be of international standard as the Hockey World Cup is to be held there in January 2020. Work is also progressing on the upgrade of the equestrian facility.
“The hockey facility needs to be completed not only in time for the Cup but to also free up the land it presently occupies.
“Any delays will impact on constructing the new section of SH18 and the completion date for the entire project.”
The detailed design for the new section of highway and the busway extension to the Albany Station is well advanced and work has already commenced on widening a section of SH1 and the construction of three of the 18 bridges and ramp connections that will be required as part of the project.
Fulton Hogan and HEB have combined resources for the project works: “With a blending of both plant and a 350 labour force making up the work crews,” says Andrew.
“We will and are utilising subcontractors for all vertical building work such as the hockey clubrooms and bus stations, and for the relocation of utilities.
“This will include a specialist pipe contractor using a boring (AGB) machine to pipe jack the installation of two sewer pipe connections under SH1.”
The machine will install two 1.95-metre diametre pipelines without the need for trenching. A pit is excavated on either side of the highway where the pipe is to be installed, and the machine set in motion to bore through the dividing soil, with the pipe jacked behind using hydraulic rams until it emerges at the exit pit.
Everything else, including the earthworks, drainage, lying of the base course, pavement, retaining walls, and bridge construction work is being undertaken by the JV contractors.
Andrew says the new section of highway does not involve a large amount of earthworks, with around one million cubic metres of material (mainly Waitemata clay) excavated for cut to fill (which will require some stabilisation), cut to waste of unsuitable material and some import to fill.
Where SH1 intersects with SH18, the intersection will be upgraded with two, 260-metre-long viaducts carrying SH18 traffic up and over a local road (Caribbean Drive), and a new underpass will connect southbound SH1 traffic onto SH18.
The strengthening and widening work will involve two kilometres of existing SH18 (Upper Harbour Highway) between the Constellation Drive interchange and the Albany Highway, and a four kilometre section of SH1 which will be widened in both directions.
“To minimise traffic disruption on SH1 we are first widening the north-bound side. We will then move all the traffic lanes west to allow construction of the south-bound side, and then split the traffic between the west and east sides and construct the central median,” says Andrew.
“To accomplish this, the lanes have been slightly reduced in width, down from 3.5 metres to 3.25 metres and this has not shown any decrease in travel time through the site.”
The surface paving will be epoxy modified open graded porous asphalt for both the new section of highway and the widened parts of SHs 1 and 18.
The project will also include an extension of the dedicated northern busway from the Constellation Station to the Albany Station, a distance of four kilometres. The Constellation Station will be upgraded and a new station at Rosedale is likely to be constructed within the next four years.
Rosedale station will be unusual in that it will be built on a widened, 90 metre-long section of the bridge that crosses over Rosedale Road.
This would make it the only bus station built on a bridge in this country, with commuters using feeder bus services from around the surrounding area as there will be no large car parking facility.
Access will be via stairs and lifts from Rosedale Road, with the design also allowing for the station to be converted for use by light rail.
“At this stage, and while we have provided the design and a cost for this station to Auckland Transport, it is presently not part of this project and could be constructed under a separate contract,” says Andrew.
For the busway, which will run alongside the highway, concrete retaining walls will be constructed to provide vertical separation as it will travel both above and below the highway level in places.
The project incorporates a number of large structures and components, with 18 bridges to be constructed using 350 super-tee beams and over 10,000 concrete pre-cast elements featuring in-situ designs will be installed on the six kilometres of busway retaining walls.
A unique, dual purpose 100-metre-long cycle and pedestrian bridge (Tirohanga Whanui), part of the six kilometre long shared cycle/pedestrian path, is to be constructed to provide access between Pine Hill, East Coast Bays and Albany.
It will also carry a bulk water main across SH1. This truss-section, steel bridge, which has been fabricated in three sections by Whangarei based Culham Engineering, is unusual in design, being a bright red lattice-like structure based on a design by local iwi artist Graham Tipene.
It is expected this improvement project once completed will siphon some traffic away from the often congested SH1, which is currently the only main artery for traffic heading north-south to and from the North Shore, Auckland city and the port, with traffic using SH18 predicted to be in the region of 1300 vehicles per hour northbound and 1600 per hour westbound.
“This project will help realise the full benefits of the Western Ring Route and give the travelling public an alternative to SH1 and over the Auckland Harbour Bridge,” says the Transport Agency’s senior manager for project delivery, Chris Hunt.