The Green Party and Campaign for Better Transport are concerned a business case for the harbour crossing is being prepared before the western ring route can be mostly completed in 2017 and the rail link built by the early 2020s.
Transport Agency northern director Ernst Zollner is confident any influence those may have on future demand can be modelled in advance.
He said the agency could not wait until the ring route was completed with a $450 million tie-in to the Northern Motorway by 2021.
He added that until a business case could be compiled, there was no certainty another harbour crossing would be needed.
The Auckland budget allocates $1.175 billion for public transport and $91 million for cycleways and walking paths.
Green Party transport spokeswoman Julie Anne Genter is concerned only 5 per cent of the funding will be spent on busway or rail infrastructure.
"Auckland's public transport system is at breaking point, with people crammed into buses and trains at peak time, and yet National refuses to start building the urgently needed City Rail Link."
The national transport budget is 15 per cent heftier than what was spent over the past three years, and the Government is contributing $10.5 billion from fuel taxes, leaving local councils to pay $3.4 billion.
Christchurch receives the second largest allocation, of $1.575 billion, followed by Wellington's $1.439 billion. The Waikato gains $1.812 billion, compared with the Bay of Plenty's $591 million and Northland's $460 million.
Funding
• Western Ring Route from Mt Roskill to Westgate budget up from $2b to $2.27b.
• Southern Mway widening: $268m
• Airport Mway: $120m
• Design and property purchases for freight routes between Penrose and Onehunga: $78m
• Bus interchanges at Manukau, Otahuhu and Te Atatu: $24m
