Low fuel prices are contributing to Tauranga's increasingly congested roads, with a big drop in the number of adults and tertiary students catching the bus.

The spate of crashes which gridlocked roads along the 15th Ave corridor on Wednesday highlighted growing concern with the ability of the network to bounce back quickly from disruptions.

Mayor Stuart Crosby said peak traffic delays had increased across the city since the middle of last year. He put it down to lower fuel costs putting more cars on the road more often, the withdrawal of free bus services and Tauranga's growth.

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Latest figures on Tauranga's BayHopper bus service showed the number of adults using buses had dropped by nearly 13 per cent and tertiary students by 11 per cent for the nine months to March compared to the same period a year earlier.

Offsetting the drop was a 38 per cent rise in the number of children catching the bus and a 5 per cent increase in senior SuperGold passengers. Child passengers included intermediate and college pupils who now had the option of using BayHopper services to get to school.

Bay of Plenty Regional Council's public transport subcommittee chairman Lyall Thurston said there was a direct correlation between drops in fuel prices and people catching the bus.

"When the cost of petrol goes down, people tend to get their car out of the garage."

But the drop in adults and tertiary students catching the bus was not the only reason for Tauranga's busier roads. "It is a mixture of a whole raft of things. A major contributing factor is the phenomenal growth in Tauranga, it's nothing short of staggering," he said.

This growth meant it was a challenge to keep the city's public transport system efficient, he said.

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One of Tauranga's transport issues was its unique geography of being built around the harbour and estuaries.

Mr Thurston said the subcommittee had recommended that the hot spot of Welcome Bay would continue to operate a "banker bus" that followed behind scheduled services to scoop up people left behind by buses reaching capacity.

The banker bus would operate until the outcome of a public transport network review needed for when the council calls for tenders to operate the bus service. The current contract expires in December 2017.

Part of the longer term planning work was to review the basis on which the regional council set fares for its contracted bus services. The council's target was for fares to contribute 35 to 40 per cent of costs by 2018.

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The subcommittee made an "in principle" decision earlier this year to increase fares by 5 per cent from the start of next year. It could be reviewed as more information came to light on patronage trends and inflation.

Other data presented to this week's public transport meeting showed there had scarcely been any impact on patronage of Tauranga's SchoolHopper service from this year's student fare increase.

There was a suggestion that the fare increase had led to more pupils being driven to school - worsening the congestion clearly evident between term breaks and when schools were operating.

SchoolHopper patronage dropped 1 per cent (36 passengers a day) between the first two terms of this year and the same period in 2015.