Timeline: Transmission Gully's 103-year history

There's been public interest in a route inland through Transmission Gully for more than 100 years.

Spanning multiple governments since the first chunk of dirt was turned (former Prime Minister John Key was the one holding the shovel) and multiple completion dates later, the $1.25 billion motorway has finally opened.

1919: A headline reading 'Transport links with Manawatu' makes page 4 of The Evening Post documenting Ōtaki MP William Field's proposal for "road and railway communications between Wellington and the coastal plain that begins at Paekākāriki".

1940s: Proposals to develop the route for military purposes floated

1980s: Wellington Regional Council first seriously considers building a route through Transmission Gully

1996: Designation was sought to include the proposed route in district plans after the region realised the project would not be possible through normal funding means

1997: Designation is approved and accepted by Transit NZ with modifications

2005: $405 million in funding announced by Minister of Transport to improve the road between Linden and MacKay's Crossing

2006: Government's transport planners agree to investigate an inland route instead up upgrading and widening the coastal road

2008:

• January: Transit Wellington regional manager Graeme Taylor says they are on schedule to have scheme assessment complete by mid-year
• June: Government gives the project the green light, despite a shortfall of $600 million. The route is moved slightly from original plan. Regional mayors still to agree
• July: New route is revealed, Wellington Regional Council and Transit say this will save $275 million. The revised cost of the project is $1.025 billion
• October: Wellington City Council threatens to pull support for Transmission Gully after Porirua reveals plans for a business park near the route

2009:

• January: Public consultation finds 88.6 percent support for Transmission Gully proposal
• March: Transport Minister Steven Joyce says previous government had not set aside $400 million for the project, expects decision on whether to build it to be made by end of year
• December: National government gives the project the green light, tolls still likely

2010:

• Waka Kotahi engaged with iwi, community groups, statutory agencies and territorial/local authority stakeholders on design and environmental matters
• The agency lodged a request with the EPA seeking changes to the Wellington Regional Freshwater Plan

2011:

• September: Transmission Gully project is fast-tracked by the government by referring it to an independent board of injuiry
• Transport Agency, Porirua City Council and Transpower jointly seek approval to build the 27km route
• October: The board of injuiry announces its final decision on the request for changes to the Wellington Regional Freshwater Plan
• November: Rational Transport Society challenges the legality of the development on environmental grounds

2012: Independent board of injuiry administered by Environmental Protection Authority grants Transport Agency, Porirua City Council and Transpower consent for the motorway. Funding process still needed

2013:

• NZTA confirms to a parliamentary committee that a Public Private Partnership would cost the taxpayer three times as much as if the agency built the road itself. Cabinet papers show the agency would pay service payment totalling about $2.4 billion over 25 years. It will cost $1 billion, plus ongoing maintainance, if the agency builds it itself
• April: NZTA selects two foreign-led consortiums Wellington Gateway Partnership and Positive Connection to bid for contract
• Build expected to begin second half of 2014

2014:

• July: Waka Kotahi and Wellington Gateway Partnership sign a Public Private Partnership (PPP) for the design, construction, finance, operation and maintance of the new motorway.
• September: Prime Minister John Key turns first sod on Transmission Gully
• A number of midden found
• October: Transport Minister officially marks start of site works
• November: Government considers raising the speed limit to 110 km
• Road tolls shelved

2016: Project delayed by a month after Kaikōura earthquake

2017: Developers underestimate amount of earthworks required by 50 percent, new resource consents sought for extra 3 million cubic metres of earthworks

2018:

• One hundred workers brought in from the Phillippines to operate heavy machinery
• Road tolls back on the table under Labour government

2019:

• Survey finds runoff from the project is contributing to a massive buildup of sludge in Porirua Harbour that's suffocating wildlife.
• NZTA rejects road tolls, decides motorway will be free
• New Zealand Transport Agency says delays to some "critical construction" of the project mean they have to reassess the May 2020 opening date
• A Porirua City Council official tells Stuff the opening is now likely to be November next year

2020:

• Transmission Gully originially scheduled to open for traffic
• Poject cost blows out by extra $191 million. The Transport Agency says it settled a dispute with the joint venture builder by agreeing to pay the extra sum and avoid costly and lengthy legal action. It says the cost blowout was because of delays and the need for extra earthworks.
• February: Transmission Gully is now expected to be finished by 1 November, or the builder could be fined $16,000 per day. It will be hit with a further $10 million charge if not complete by 18 December, NZTA says
• Covid-19 pandemic hits and project is put on hold
• Many of the roading sub-contractors are no longer employed and the opening is extended into 2021
• The Transport Agency admits that sections of the motorway need to be re-laid after an error
• May: he project gets a $14 million boost to kick the project back into action as negotiations continue
• July: NZTA coughs up another $5 million to keep workers on site
• August: After five months of negotiations, NZTA Waka Kotahi has been forced to fork out another $208 million - which includes changing the design - to get the troubled road back on track
• November: The Transport Agency calls for tenders to build an additional 650m merge lane extension at Linden heading south, towards Wellington
• NZTA issues a promise: Come hell or highwater, Wellington's Transmission Gully will be open for motorists next September

2021:

• A review finds the project was flawed from the start. The National Party defends is role in the project
• The company in charge of building Transmission Gully is convicted and fined $70,000 for unconsented earthworks and discharging sediment into the Belmont Regional Park in early 2019
• August: The project is unlikely to meet the September deadline
• 18 September: Contractor advises NZTA it can no longer meet 27 September deadline
• A builder of the much-delayed motorway project goes to court seeking $75 million from the engineer alleging "defective" designs when costing the project
• November: Only a quarter of the safety and quality assurance tests required under the contract to build Transmission Gully have been signed off on, as the opening date for the highway refuses to be pinned down
• December: NZTA puts pressure on the contractor to meet Christmas target
• Road surfacing reports released by the Transport Agency show attempted repairs to Transmission Gully actually made the highway worse

2022:

• February: Transport Minister says he expects Transmission Gully to be open by the end of the year
• March: A litter of kittens is found on the constuction site
• The Transport Agency allows the road builder CPB HEB todefer completion of 19 safety and quality assurance tests, and drops some requirements of a further 30 tests
• 17 March: NZTA tells the contractor it must open the Wellington highway within the next two weeks
• 30 March: The official opening of Transmission Gully finally takes place with the road expected to open to the public 31 March

Prime Minister Jacinda Ardern cuts the ribbon on Transmission Gully during the opening ceremony, 30 March 2022. Photo: RNZ / Jake McKee