Heavy electric buses being driven where they shouldn't are creating ruts and damaging Tauranga roads, the city council says.
And senior Tauranga City Council staff say they are struggling to find the right people at Bay of Plenty Regional Council to put a stop to it.
The two councils are also at odds over bus patronage data, which city commissioners have waited a year for the regional council - which manages bus routes and use - to provide.
The bus issues were discussed in a meeting of the Tauranga Joint Public Transport Committee on Monday.
The discussion about damage caused by electric buses was raised as the committee considered a trial, proposed by a local commercial group, of electric buses at five-minute frequencies along Cameron Rd.
Tauranga City Council director of transport Brendan Bisley raised concerns at the trial's proposed bus design and axle load.
He said the city's existing electric buses already ran 10.3 tonne rear axles - about 25 per cent more than a standard heavy commercial axle.
The extra weight was mostly caused by the electric buses' batteries and meant more load for roads in Tauranga which are not equipped to handle it.
In a report to the meeting, Bisley said the council had only approved the regional council's five electric buses for use along Cameron Rd where pavements could better cope with the high axle loads.
"But the buses are being used across the city, outside the terms of the trial approval," he said.
"Council staff have recently sought to discuss this with regional council and the bus operators but have been struggling to find who are the right people to discuss the concerns to ensure the electric buses are only used on the approved route."
Bisley told the Bay of Plenty Times the combination of the extra weight and buses travelling a route multiple times a day was damaging roads.
"We can start to see pavement distress in the form of ruts or failed areas over time.
"Our residential streets are not designed to have heavy vehicles use them regularly. They can cope with occasional use, such as a furniture removal truck, or a rubbish truck once a week," he said.
Asked how this problem would be managed, given the Government-imposed deadline to decarbonise New Zealand's bus fleet by 2035, Bisley said buses could be designed with less weight on the rear axle.
Technology advancements could also reduce the weight of low emission buses, he said.
In the meeting, committee deputy chairperson and regional councillor Andrew von Dadelszen said smaller electric buses could be a viable option to help address roading damage.
"That's why I think we should consider that next lot of electric buses to be smaller, because of the problems we have with the big electric buses going around cul de sacs and residential streets and the damage they are doing. They are not designed for that."
The regional council was also asked in the meeting when it would deliver bus patronage figures requested by Tauranga commissioner Stephen Selwood in March last year.
Committee and commission chair Anne Tolley had previously followed up Selwood's request in October. The regional council responded in November but did not provide the information requested. Tolley followed up again in the meeting.
Regional council transport and urban planning manager James Llewellyn said the challenge was getting "data sets" to "talk to each other".
"We are certainly looking at a plan as to how we can provide that data and information".
Appearing frustrated, Tolley said she would write another letter.
Von Dadelszen said: "I don't want to get into tit for tat. I want us to work constructively together."
He said the data was crucial and that he and fellow regional councillor Paula Thompson would be "pushing our staff on the data issue as far as we can".
Regional council general manager of strategy and science Namouta Poutasi said the council had a data action plan.
The committee accepted both the trial's report and a report outlining the wait for bus patronage data.
In response to the concerns raised by Bisley, von Dadelszen said after the meeting that he disputed the introduction of the city's electric buses were ever part of a trial and the regional council "has endeavoured to minimise use on suburban streets".