CMJ - Project Development

HISTORY

The Central Motorway Junction (CMJ) is the heart of Auckland's motorway network and is broadly configured as a 'T' interchange between the Northern/ Southern Motorways and the Northwestern Motorway.

Planning for the Auckland motorway system began in earnest in 1955 with the release of the 'Master Transportation Plan' by the Auckland Regional Planning Authority. Between 1965 and 1968, engineering consultants De Leuw Cather, from the United States, were commissioned to review the adequacy of the Auckland Master Plan and found that the traffic forecasts were based on data that would under estimate traffic volumes.

Following a review of the proposed layout, De Leuw Cather recommended connecting the Southern Motorway to the Auckland Harbour Bridge (AHB) through Kingsland and Ponsonby, but this was rejected in favour of the current location of the Southern and Northern Motorways.

Various components of CMJ were built in the 1970's to provide links between the north, south and northwest. The original CMJ design included a link from the Karangahape Road area to a new motorway that ran parallel to Dominion Road, which would have provided a more direct link to the airport. For various reasons, this link was not completed.

The link from the Northwestern Motorway to Grafton Gully was opened in 1988, and in 1989 the link from the Northwestern Motorway to the Southern Motorway was completed.

THE EXISTING NETWORK

CMJ is bound by Wellington St to the north, Newmarket Viaduct to the south and Bond St to the northwest.

CMJ is the busiest section of road in New Zealand, with about 200,000 vehicles passing through each day. During off peak times traffic volumes only drop to about 80% of peak levels. The following situations describe the existing congestion experienced through CMJ:

Northbound on the Southern Motorway:

The Gillies Ave on-ramp is heavily used during peak periods. Congestion is due in part to weaving traffic and very large volumes of traffic using Khyber Pass Rd, Wellesley St and Northwestern Motorway off-ramps.

The afternoon peak traffic travelling to the AHB is as heavy as the morning peak traffic travelling south.

Heavy volumes of traffic heading into the CBD via Nelson St, and north to the Harbour Bridge cause congestion during both peaks. The right hand exit to the Nelson St off-ramp contributes to this problem.

Traffic entering the motorway at the Wellington St on-ramp causes congestion during the afternoon peak.

Southbound on the Southern Motorway:

There are no off-ramps from the motorway between Cook St and Gillies Ave southbound. There are 4 on-ramps in this length. Nearly one third of traffic from the Harbour Bridge travels beyond Gillies Ave.

Heavy traffic volumes using the main on-ramp to the Southern Motorway at Hobson St cause congestion on city streets and on the motorway, especially in the afternoon peak.

The Gillies Ave exit is heavily used. Traffic weaving to exit at this location encounter traffic merging from the Symonds/Grafton/Khyber on-ramps, causing congestion.

Eastbound on the Northwestern Motorway:

The Northwestern Motorway is heavily used particularly during the morning peak. Congestion is made worse because traffic entering on the left and exiting to the city (on the right) must weave across traffic exiting to the Port and Southern Motorway.

Westbound on the Northwestern Motorway:

Heavy traffic flows on the link from the Southern Motorway to the Northwestern Motorway cause congestion during the afternoon peak westbound on the Northwestern Motorway. Queues back up to further disrupt the Southern Motorway.

Current deficiencies of the existing network include:

• No motorway links are provided for traffic travelling to and from the Northwestern and Northern Motorways.
• No motorway links are provided for traffic travelling to and from the Northern Motorway and the Port (via Grafton Gully).
• The Southern Motorway is at or above capacity in both the morning and evening peaks and minor interruption in flow (i.e: an accident) creates major delays.
• There is congestion at the Southern Motorway, Newton Rd and Nelson St off-ramps from the Northwestern Motorway restricting traffic flows.
• There is a right hand exit from the Southern Motorway to Nelson St, where a left hand exit should be.

THE CMJ SCHEME

CMJ Stage 1

CMJ Stage 1 covers the area between the Symonds St over-bridge and Gillies Ave and includes the addition of extra lanes southbound. Work began in September 2002 was completed in stages with the final stage completed in January 2005.

For more details on Stage 1 work please click on the link below.

Stage 1 >

CMJ Stage 2

CMJ Stage 2 covers the "core" Central Motorway Junction area - bound by Cook Street to the north, Symonds Street in the south and St Lukes/Western Springs to the Northwestern Motorway. The initial CMJ Stage 2 project area was expanded in November 2004 with the addition of the Northern Tie-in works. In February 2005 the Transit project to add an auxiliary lane from Newton Road to the Northwestern Motorway to Western Springs, was also incorporated into the CMJ Stage 2 works. These additions to the CMJ Stage 2 project are scheduled for completion late 2006.

A contract has been awarded for this section of the project and work is underway.

For more details on Stage 2 please click on the link below.

Stage 2 >

ACTIVITIES / MILESTONES

Transit is bringing an early Christmas present to Auckland motorists with the opening of four new motorway links on the CMJ.

The new links form what is known as the Northern Tie-In, which joins the Northwestern Motorway with the Northern Motorway, completing all motorway to motorway connections in the central city and heralding the completion of the entire CMJ project.

The Northern Tie-In comprises the following connections:

Northern to Northwestern (SH1 -SH16 heading west)

Motorists can now drive direct from the North Shore, across the Harbour Bridge, to West Auckland on the Northwestern Motorway.

Northwestern to Northern (SH16 -SH1 heading north)

Motorists can now drive direct from West Auckland on the Northwestern Motorway, across the Harbour Bridge to the North Shore.

Northern to Port (SH1 - SH16 heading east)

Motorists can now drive direct from the North Shore, across the Harbour Bridge to the Eastern suburbs - via Grafton Gully and the Ports of Auckland.

Port to Northern (SH16 -SH1 heading north)

Motorists can now drive direct from the Eastern suburbs, across the Harbour Bridge to the North Shore - via Grafton Gully and the Ports of Auckland.

Due to the tight restrictions on space in the CMJ, various measures have been taken to fit all links in. These range from lowering an entire section of the motorway by around 6.5 metres to build the North to Northwest bridge above, to the veritable musical chairs style of closures and lane shifts needed to move all traffic onto the right lanes.

Over the four years it has taken to complete the CMJ project, it has been described in all manner of ways. By the public it is referred to as Spaghetti Junction; by Transit project managers it has been summed up as a complex network of “overs and unders”; and by one journalist it has been described as looking like “the cat got in the knitting.”