"This is just the starting point - we may look to go heavier again as part of a larger review.
"There is also potential to extend these rules to allow heavier buses to travel inter-city, carrying more travellers to the regions."
Ritchies Transport already has two double-deckers, each with 86 seats and standing capacity for 15 passengers, running up and down Auckland Northern Busway to Britomart.
That company has another 15 of the same capacity on order from China, all of which it expects to add to its operation by January.
But Auckland Transport chairman Lester Levy says they will be joined by 38 more buses across two other city fleets - all of which are expected to have 91 seats with standing capacity for 11 passengers and are being built in Tauranga.
That will mean carrying capacity of just over 100 passengers for all the new buses, compared with a maximum of 70 for single-deck carriers.
Auckland's largest transport operator, NZ Bus, is expected to roll out 23 double-deckers between April and July on its Mt Eden Rd and Albany to Newmarket services, and the first of 15 on order by Howick and Eastern will be ready in October for runs from Botany to the CBD.
Dr Levy said an unprecedented increase in public transport patronage looked set to continue, and the investments by the three companies in their fleets reinforced confidence in more growth.
"There is only so much road-widening we can so in some areas, so we have to look at more innovative and different ways of utilising what is a limited space," he said.
"Double-deckers along with increased frequency and reliability on buses and trains are key to reducing the city's number one problem, which is congestion."
But Dr Levy has previously warned that even double-deckers would only "buy a little time" before trams would be needed to carry more people without overloading central Auckland streets with buses.
Auckland Transport has so far spent almost $2 million preparing routes for double-deckers, mainly on the Botany route as the Northern Busway did not need any modifications.
It has decided against scheduling Dominion Rd for double-deckers for now, meaning there will be no immediate need to alter the historic route's heritage verandahs, but says some "property requiring adjustments" will be needed in Upper Symonds St and Mt Eden Rd.
Auckland buses provided just over 60 million passenger trips in the year to July 31, a 6.9 per cent increase from the previous 12 months.
Double decker buses
Ritchies Transport: Already has two 86-seater double deckers on its Northern Express service. Expects to add 15 or 16 more by January.
NZ Bus: Expects to have 15 double-deckers with 91 seats running on Mt Eden Rd to the CBD and eight on its Albany to Newmarket route by July.
Howick and Eastern: Expects to have two 91-seater double deckers running on its Botany-CBD route in October, to be joined in subsequent months by 13 more on that and its Howick service.
