Rail patronage and city-centre employment targets set by the Government to allow an early start on Auckland's Central Rail Link are unrealistic and impractical, a report commissioned by the council says.
Auckland Mayor Len Brown wants to fast-track the rail link and start construction in 2016.
The Government has promised to fund half of the $3 billion city rail link for construction to start in 2020.
It would consider bringing that forward if CBD employment grew 25 per cent on 2012 levels or if rail use was on track to hit 20 million trips a year by 2020.
However, the report from consultants PwC says the governments targets are taken from data that did not reflect the needs or economic outcomes of the rail link.
The CRL targets were taken from the 2012 City Centre Future Access Study in a way that did not take into account the purpose of the study, the report said.
The Government's rail link patronage target was technically achievable and not inconsistent with growth rates observed since the opening of Britomart, the report said.
However, the timing of full rail electrification in 2015 and 2016 meant that growth was not expected to occur until it was too late to impact on the timing of the Central Rail Link.
The Government's employment target was practically unachievable given short and medium-term constraints on city-centre office space. That meant it would be impossible to accommodate an additional 22,000 jobs in the city centre before 2017, the report said.
Falling city-centre office vacancy rates, coupled with the lead time for construction of new office towers, meant that there was no capacity to accommodate a 25 per cent increase in city-centre employment by 2017.
Brown said a 2016 start to building the rail link was vital to Auckland's economic development and would help to prevent crippling peak-hour road congestion.
"Without the [Central Rail Link], by 2021 Auckland's bus network will have reached capacity, and speeds on city roads will have dropped to a creeping 7kmh during peak time," he said.
The rail link would double the capacity of Auckland's rail network, providing twice as many train journeys and passengers across the entire rail network and trains at most stations every 5-10 minutes at peak, the mayor said.
However, the Ministry of Transport said the targets were reasonable and the mayor's case for starting the rail link in 2016 was based on the same figures.
The 2020 start date was appropriate because growth projections indicated the tunnel would still be open well ahead of demand, the ministry said.
"Arguments that the employment growth target is challenging because the CBD growth can not happen at this rate apply even more strongly to the case for starting the City Rail Link early," a Ministry of Transport spokesperson said.
The PwC report proposed alternative targets for a 2016 CRL start date.
For rail patronage targets until the completion of electrification of Auckland's trains, PwC proposed continued growth at levels observed since the opening of Britomart in 2002. That equated to an annual increase of about 800,000 rail trips.
After rail electrification was completed through 2015/16 rail patronage growth should increase above the previously observed trend, equating to an annual increase in rail patronage of 1.5 million to 2 million trips.
A two-stage target was appropriate given that rail electrification was expected to be associated with a step change in the speed and capacity of Auckland's rail system.
The full impact of this change was not likely to be felt before 2016-2017, and as a result it would be premature to delay the rail link based on outcomes observed before that date, the report said.
Because of constraints on meeting employment targets by 2017, it was more realistic to focus on demand for existing capacity in the city centre and the market response to this demand, the report said.
Sufficient additional city-centre office space to meet forecast employment growth by 2021 should be consented and progressed towards construction, it said.
Speaking at a transport summit this morning Brown said he would not give up on moving the rail link start date forward.
"Three-plus years ago I lost count of the number of people who told me that the Government didn't like the CRL would never back it, and that I should drop it," Brown said.
"Now, those same people are telling me: 'they say 2026, so 2026 it is ... drop it.' Interesting," he said.
"No matter where I go in the region, and indeed the country, the most consistent message I hear is: 'Len, you need to fix Auckland's transport,'" Brown said.
When it comes to holidaying in New Zealand do you choose to drive or fly?