Project details

Mt Roskill Extension is a key part of the Western Ring Route. The Western Ring Route will provide quicker and safer travel between North Shore, Waitakere, Auckland and Manukau, and will play an important role in reducing central Auckland congestion, by enabling traffic to completely bypass the Auckland Harbour Bridge.

Features

Key facts

Four-lane motorway from Queenstown Road through to Richardson Road, Mt Roskill.
4 km long.
Two interchanges at Hillsborough Road and Dominion Road.
Four bridges at May Road, Dominion Road, Hayr Road and Hillsborough Road.
Two pedestrian/cyclist bridges at Keith Hay Park and Ernie Pinches Street.
New roundabout where the motorway intersects Sandringham Road.
Maioro Street will be widened to four lanes.
A dedicated cycleway alongside the motorway is being developed in conjunction with Auckland City. Council.
Rail provision.
Estimated cost – $186 million.
Construction completed in mid-2009.

Quick facts

6,704 metres of boundary fencing.
33,300m³ of top soil.
193,600m of drainage.
15,974m² of retaining walls.
13,127m² of guard rails and safety barriers.
3,409 new trees.
250,000 new plants.
262,457m² of landscaping.
140,000m² of pavement.
800,000m³ of earthworks.
1.7km of noise walls.

Project overview

The Mt Roskill Extension project extends the Southwestern Motorway (State Highway 20) 4 kilometres into Mt Roskill, from Queenstown Road in Hillsborough.

There are interchanges at Hillsborough Road and Dominion Road, with on- and off-ramps in both directions (eastbound and westbound) and motorway overbridges for local traffic.

The extension ends at a new roundabout which links to Sandringham Road Extension. Maioro Street was widened to four lanes to accommodate motorists accessing the motorway extension.

Two pedestrian/cyclist bridges have been constructed at Keith Hay Park and Ernie Pinches Street. A dedicated cycleway was developed in conjunction with Auckland City Council and runs parallel to the motorway.

The project features two dedicated bus shoulder lanes as well as provision for a rail line in the future, connecting to the ARTA (now Auckland Transport) proposed rail link to Auckland Airport.

May Road Bridge

First motorway overbridge to open.
Constructed December 2005–December 2006.
Opened 15 December 2006.
Bridge makes driving easier for local traffic by separating the local road network from motorway traffic.
Estimated traffic flow on May Rd: 14,500 vehicles per day.
Cost: $6 million.
Height: 5.6m.
Length: 61m.
Number of beams: 24 beams, three spans.
Number of piers: two slender piers.
Width of piers: 300mm thick.
Height of piers: 16m.
Approach ramps to the bridge use a reinforced earth system, tied back to concrete facing panels.

Dominion Road Interchange

Dominion Road Bridge was the second motorway overbridge to open.
Constructed March–October 2007.
Opened 24 October 2007.
Full diamond interchange with two on-ramps and two off-ramps.
four-lane overbridge for local traffic.
Bridge will ease congestion on Dominion Road – one of Auckland’s busiest routes – by separating the local road network from motorway traffic.
Estimated traffic flow on Dominion Rd: 13,000 vehicles per day.
Cost: $1.3 million.
Height: 5.25m.
Length: 40m.
Number of beams: 26.
Number of piers: one central pier – 360mm thick and 31m high.

Hayr Road Bridge

Seven spans.
Opened October 2008.

Hillsborough Road Interchange

Hillsborough Road Bridge was third motorway overbridge to open.
Constructed January–December 2007.
Opened 28 December 2007.
Six-lane overbridge will carry traffic over Hillsborough Road while construction continues underneath, to align the future motorway and new eastbound and westbound ramps.
Full diamond interchange under construction, with two on-ramps and two off-ramps to provide access to motorway in both directions.
Estimated traffic flow on Hillsborough Road: 40,000 vehicles per day.
Estimated cost: $1.5 million.
Height: 8m.
Length: 40m.
Number of beams: 26.

Keith Hay Park pedestrian bridge

First pedestrian/cyclist bridge to open.
Constructed January 2006–February 2007.
Opened 16 February 2007.
Cost: $1.2 million.
Bridge creates safe pedestrian and cyclist access by providing a dedicated link across the Southwestern Motorway (SH20) for local residents and students from three local schools: Mt Roskill Primary, Mt Roskill Intermediate, Mt Roskill Grammar.
Estimated pedestrian flow on bridge: 2,000 people per day.
Unique features:

a cable stay bridge design allows cables to support 500 tonnes
downlights have been incorporated into a stainless steel handrail for safety.

Height: 25m above motorway level to the top of the supporting pylon.
Length: 170m.
Number of spans: 13 pre-cast concrete decking slabs.
Length of largest span: 39m across the motorway.
Number of piers: 11.
Width of piers: 600mm square at the base, spreading into a ‘Y’ shape at the top to hold the deck.
Length of pier: Varying heights up to a maximum of 5.5m.
Height of handrail: 1.4m.
Number of cables: 12.
Thickness of cable: 36mm.

Ernie Pinches pedestrian bridge

Second pedestrian/cyclist bridge to open.
Constructed August 2006–March 2007.
Opened 30 March 2007.
Cost: $1.2 million.
Bridge increases safe pedestrian and cyclist access by providing a dedicated link across the Southwestern Motorway (SH20) from Richardson Road, for local residents and students from Wesley Primary and Intermediate schools.
Estimated pedestrian flow on bridge: 500 people per day.
A cable stay bridge design allows cables to support 500 tonnes. Downlights have been incorporated into the stainless steel handrail for safety.
Height: 25m above motorway level to the top of the supporting pylon.
Length: 170m.
Number of spans: 13 pre-cast concrete decking slabs.
Length of largest span: 39m across the motorway.
Number of piers: three (one central pylon, two piers).
Width of piers: 600mm square at the base, spreading into a ‘Y’ shape at the top to hold the deck.
Height of piers: Varying heights up to a maximum of 5.5m.
Height of handrail: 1.4m.
Number of cables: 12.
Thickness of cable: 36mm.

Stoddard Road and Sandringham Road extension intersection

The motorway links to Richardson Road and Stoddard Road at a new roundabout.

These links were created by extending Maioro Street to the new roundabout, from the intersection of Maioro Street and Richardson Road.

Sandringham Road was extended from Stoddard Road to the new roundabout on SH20.

Stoddard Road was also widened and the new intersection has traffic lights in place.

Public transport

A dedicated cycleway running alongside the motorway was developed in conjunction with Auckland City Council. The cycleway links to cycle routes in Hillsborough and Mt Roskill.
Two dedicated bus shoulder lanes.
Enabling works have been completed to make provision for rail in the future and to link with ARTA’s proposed rail link to Auckland Airport.

Benefits

The Mt Roskill Extension project delivered the following benefits:

It created a key link in the Western Ring Route, easing congestion on SH1.
It improved traffic flow on local roads by separating motorway traffic and local traffic with overbridges.
It gave better public transport options with two dedicated bus lanes and provision for rail in the future.
It provides a key link to Auckland International Airport from the Auckland CBD including ARTA’s proposed rail link to the airport.

Public awareness

Local residents and the wider public were kept up to date on construction progress via media releases, letter drops, newsletters and the Transit and NZ Transport Agency websites. Major closures affecting local roads were advertised well in advance.

Online services