Creating smoother journeys.
Taharoto – Wairau Road Upgrade
Client: Auckland Transport
Project Background
Dempsey Wood was contracted by Auckland Transport to deliver Stages 6 and 8 of the Taharoto-Wairau Road Corridor Upgrade.
Project Overview
The purpose of the upgrade was to replace an old bridge to increase road capacity, provide additional traffic lanes to ease congestion, provide on-road and off-road cycle lanes, more extensive and better quality footpaths, additional pedestrian islands and improved intersections.
Taharoto / Wairau Roads and Forrest Hill Road are significant Level 2 arterial routes providing direct feeder access/egress for the Northern Motorway (SH1) as well as being principal access routes for Wairau Valley, North Shore Hospital, Smales Farm and Takapuna City Centre.
The project site was very constrained and had Westlake Girls and Westlake Boys High Schools and Forrest Hill Primary School directly adjacent or within very close proximity to the site. These schools – and the thousands of school children – required specific TTM as well as safety and stakeholder liaison planning provisions.
There were several other challenges that our team successfully overcame on this project including piling through basalt – the hardest rock in Auckland; and the identification, protection and relocation of services – many of which were pre-World War 2 and unidentified.
Scope of Works
Widening of Wairau, Taharoto and Forrest Hill Roads to accommodate a new/improved intersection. This required replacing existing pavement with a new concrete and deep lift asphalt pavement; cycle and bus lanes; footpath construction/reconstruction and upgrades; kerb and channels; streetlights; traffic signals; road marking; and landscaping and reinstatement works.
Bridge demolition and construction works undertaken using our own resources, entailing replacement of a 1939 bridge and tying the new bridge into another existing 1962 bridge within a heavily trafficked site.
Other structures including two concrete pile and precast panel walls on the new bridge approaches, a reinforced concrete L-shaped retaining wall and footpath, a 30m timber pole retaining wall and a keystone retaining wall.
Modification of existing sanitary sewers and stormwater drainage to accommodate the new kerb alignments involving the relocation of existing and installation of new catch pits, installation of new upsized manholes and complex diversion works.
Utilities relocation and installation, incorporating the challenging relocation of the gas main and watermain from the old bridge structure to the new; undergrounding of all overhead electricity cables; and relocation/installation of all other utility services.
Solutions
Development of innovative and proactive TTM / TMPs was critical in maintaining traffic flows on Level 2 roads.
This was undertaken by Dempsey Wood’s in-house Traffic Division. Pedestrian Marshals were on site to ensure safe passage for the vast number of pedestrians and access was maintained for emergency services to nearby North Shore Hospital.
Notification to the bus companies was also critical in maintaining the bus routes (school and public buses) on this major route.
Innovative solutions included value-engineering to stage the bridge demolition and concrete works in a way that enabled the gas main and watermain to be transferred directly from the old to the new structure ‘in one hit’ – this provided significant cost savings as well as reducing risks and eliminating the need for multiple shutdowns.
