Walking and cycling campaigners will ask the Government to consider according "road of national significance" status to foot and pedal links across Auckland Harbour Bridge.

Leaders of the Getacross campaign hope Prime Minister John Key's promotion of a national cycleway - for which last week's Budget allocated $50 million over three years - will boost their chances of gaining lawful access to the 50-year-old bridge.

The sum is in addition to an indicative allocation of $50 million for other cycling and walking facilities throughout the country, from which the Transport Agency says it cannot justify adding pathways to each side of the bridge for as much as $43 million.

But the campaigners intend asking Mr Key to add bridge links to a list of seven roads of national significance already announced for priority funding, following the allocation of an extra $961 million to state highways over the three years.

The seven top roading projects include digging a northbound tunnel under Victoria Park and widening the motorway between there and the harbour bridge for up to $430 million from early next year.

Transport Agency regional director Wayne McDonald said, after failing to stop more than 2000 protesters crossing the bridge eight days ago, that a walkway or cycleway would not be possible for at least 30 years, until a $4 billion set of harbour tunnels could be available for motorway traffic and passenger trains.

The agency late last year rejected a consultants' recommendation that walking and cycling paths be added to the bridge for up to $43 million, in addition to $45 million of structural strengthening already being applied to its clip-ons.

Getacross spokesman Bevan Woodward admitted the protest crossing was "a bit of an aberration" and insisted it was not the aim of the campaign to inconvenience motorists by repeating the exercise on a regular basis.

"But we're not going to wait 30 years for tunnels before getting walking and cycling on the harbour bridge," he said. "We'll either have a little add-on to the clip-ons, or maybe something much more exciting architecturally, such as a larger version of the tube you walk through at Kelly Tarlton's Underwater World.

"Imagine that suspended under the main part of the bridge - it would be a real architectural feature and really worthy of calling it the Sir Edmund Hillary Pathway."

Mr Woodward said the campaigners were hesitant about approaching the Hillary family on that idea just yet, given the controversy surrounding access to the bridge.

But the most popular suggestion from visitors to their website was for "an exciting, aspirational" pathway to be named in honour of Sir Ed, especially given the adventurer's love of Waitemata Harbour and his encouragement to New Zealanders to become more active in the outdoors.

Transport Minister Steven Joyce said yesterday that walking and cycling links would not qualify as a road of national significance, and the difficulty with adding them to the bridge was not just their cost, but also the impact the extra weight of the necessary infrastructure would have on the life of the clip-ons.