Photo: RNZ / Taiha Molyneux
Transport officials have been giving lawmakers plenty of advice about congestion charging, but will not reveal what that is.
Charges at peak times on Auckland motorways could be introduced as early as 2025, after investigations that stretch back at least six years.
However, efforts to get legislation on congestion charging through before the October election foundered.
The Ministry of Transport in an OIA response listed four lots of advice that went to previous ministers or the Cabinet during those efforts.
However, it has refused to release any of the actual advice to RNZ, on the grounds it needed to protect the confidentiality of advice tendered by ministers and officials.
Congestion costs Auckland an estimated $1.3 billion a year.
Auckland Transport and Auckland Council have teamed up to advance the plan to introduce congestion charges to the city's roads within the next two years, hoping to coax commuters off the motorways during peak hour.
In November, the council's Transport and Infrastructure Committee voted in favour of setting up a team to oversee the implementation of the 'time of use' charges.
Mayor Wayne Brown had earlier proposed charges between $3.50 and $5 a trip for travel during peak times on State Highway 1 between Penrose and Greenlane, and State Highway 16 between Lincoln Road and Te Atatū Road.
There is concern the charges will hit the worse-off the hardest, however, the Employers and Manufacturers Association says the extra funds would bring economic and social benefits to the city.