Auckland's successful Northern Busway has been set back by a Government decision to exclude an extension to Albany from an $815 million package of accelerated roading projects.

A Treasury paper shows the Government considered a Transport Agency plan to extend the dedicated bus highway from Constellation Drive, but backed off after being told it would cost an extra $250 million.

But it is pressing ahead with northern corridor roading improvements costing $460 million, including a full motorway-to-motorway "elbow" link extending four kilometres from State Highway 18 to Greville Rd on SH1 - parallel to the first part of the busway extension route of similar length.

Also included in May's Budget was $210 million for Southern Motorway projects from Manurewa to Papakura and $140 million for State Highway 20A to the airport from the city.


Labour's transport spokesman Phil Twyford says it reflects "the entrenched motorways bias that this Government has."

"This is more evidence of this Government's blind irrationality when it comes to public transport," he said yesterday.

The Treasury paper points to 2019-20 as the target date for completing the rest of the roading components, including sweeping motorway-to-motorway ramps above Constellation Drive, but gives no indication when the busway will be extended.

But it reports Transport Agency advice that investigations and route projection for the busway - expected ultimately to run alongside the motorway to the east - can continue without extra financial help.

A spokesman for Transport Minister Gerry Brownlee said last night that although a $350 million Government loan to the agency for motorway improvements did not provide for the busway extension, the project "has not been dropped from the list of projects that may be considered for acceleration in the future".

But Auckland transport blogger Matt Lowrie said agency officials had indicated to him their surprise that busway funding had been excluded.

The busway snub has disappointed former North Shore mayor George Wood, now an Auckland councillor. Mr Wood, under whose mayoralty the existing 6.5km two-lane busway was built from Takapuna to Constellation Drive for $300 million, said he was "immensely" disappointed by the knockback.