Mrs Blennerhassett has two children riding the SchoolHopper bus from Welcome Bay to Tauranga Boys' College and Tauranga Intermediate and said it was a "lucky day" if they managed to get a seat.
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Since starting the petition she had received support from other parents.
"One mum told me her child stood at the bus stop for 40 minutes waiting for another bus because the school bus was too full and the driver told her she couldn't get on and would have to catch a BayHopper."
She said young children would not know which public bus route to get on or where to get off if this happened.
The price of riding the bus to school was already a thorn in the side of parents, as at the start of the school year, the price had increased from $1.15 to $1.51 for a child/student fare for a Smartride concession trip and $1.90 without the concession, she said.
Mrs Blennerhassett said her two kids catching the bus to school was costing her $1200 a year but they were not receiving the service they were paying for.
"People complained about the buses before, when they were free, but now that they are user pays I expect better service than what we're getting."
"Ideally what would be achieved is council puts on two buses on the overcrowded runs.
"The buses could leave the depot at the same time and tag-team follow each other and when the first bus gets full it would head to the schools while the second bus carries on to pick up the other kids."
Mrs Blennerhassett said she planned to speak to the regional council and present the petition to them.
She said overcrowding had been going on since February last year.
"They've had a year to try to sort it and they haven't."
Bay of Plenty Regional Council councillor Lyall Thurston, who chairs the public transport subcommittee, told the Bay of Plenty Times Weekend the bus service was experiencing "first-term teething issues" due to an increase in demand for SchoolHopper services.
Councillor and chair of the public transport subcommittee Lyall Thurston said of the 51 routes that operate each day, it had become clear at least three - Welcome Bay, Ohauiti and Hairini - were operating at capacity.
He said the start of the year was always a balancing act as council had no prior knowledge of changes in population growth, roll numbers or confirmed numbers of which children would take the bus.
Larger buses had already been moved to the areas experiencing capacity issues.
"We're working with the bus companies and NZ Transport Agency to see what can be done," Cr Thurston said.