North Shore parents claim students are sitting on knees, standing in door ways and being left behind amid reports of overcrowded buses.
But, Auckland Transport (AT) added another large bus on the service after one incident of overcrowding two weeks ago and believed that had largely solved the problem.
Westlake Boys' and Girls' high schools, Carmel and Rosmini colleges shared a bus service which was often overcrowded after school finished.
Yesterday afternoon, hundreds of Rosmini College students rushed to buses outside the school gate.
The buses came in two waves, with the first leaving almost empty by 3.18pm and the second convoy attracting large numbers of students desperate to get home.
A crowd of students travelling to Verrans Corner in Birkdale said the buses were always very crowded.
"You have to get there early so you can get a seat," one said. "Otherwise you have to stand up with your heavy bag."
"Some people have to stand by the doors," another said.
The students said there were normally three people to a seat.
"It's worse in summer when everyone is hot, sweaty and stinky," one said.
"It's way too packed. Some people get crashed by the doors, and if the bus stops too fast everyone falls over like Ten Pin Bowling," another added.
A Rosmini College staff member in charge of patrolling the bus stop said parents often complained about the overcrowding.
"But there is not a lot I can do. I can only ring the bus company and ask for a second bus but if they say no then that is their call," he said.
He said the school let students on to the bus in "form order" to make sure they were safe.
"The main reason being that it is safer to let the bigger kids on first then the younger kids," he said.
And if students were left behind, he took them to the school office and let them call their parents.
Parent Libby Haskell said her daughter, a Year 10 student at Westlake Girls', rode the bus and had been left behind several times due to overcrowding.
The Starship Hospital paediatric emergency nurse feared it would take a serious injury for there to be some action from Auckland Transport.
The council-owned organisation had underestimated the number of students that would be riding the service, she said.
"From my experience, this is a bit of an ongoing issue. It has been worse this year than last year.
"It's usually at the end of the school day, where there are not enough seats.
"Kid are standing against the footwell and allegedly sitting on laps."
Every time there was overcrowding Haskell reported it through the AT feedback form - but she has not had a reply since her first report on February 13.
"Maybe there are more students taking public transport, there is talk of them [AT] putting on a bigger bus, but it doesn't appear to have happened," she said.
Vanessa Campbell posted to a North Shore community page saying a student had been injured aboard a school bus leaving from Carmel College.
She alleged more than 29 students were standing aboard the bus.
"When they got to Westlake ... a girl's foot was caught in the door as she was right up against it," she said.
Carmel College principal Christine Allen said the school received reports of overcrowding on the Devonport bus route "at least once or twice a week".
She confirmed the school had received an email regarding a student who had her leg trapped in the closing door of a full bus.
"There were three students in the office complaining the other day that they had been left behind.
"They said 'we've been left on the side of the road, the bus wouldn't stop for us' they were genuine about it," Allen said
The route began at Westlake Boys' High School then went to Carmel College.
"Depending on how many Westlake boys gets on depends on how many of our girls can get on," Allen said.
"Obviously if it's overcrowded with our girls, there will be no one to get on after that."
Allen said several students had been left on the side of the road for three days in a row at the start of the school year due to the full bus.
But they had been put on another bus close by which had resolved the issue, she said.
As a school they did not have much input, Allen said. All they could do was report it to AT if there was an issue and encourage parents to do the same.
"Some days they are overcrowded, sometimes they are not. The numbers seem to fluctuate."
AT monitored the capacity of school buses daily and acted quickly when there was a problem, AT media relations manager Mark Hannan said.
"When we noticed overcrowding the week before last, we asked the operator NZ Bus to help.
"From Friday 22 Feb, they have put on an extra large bus on this route."
Last week the numbers on the bus averaged 70 or 80 per cent of the 87 spaces.
The company would continue to monitor the numbers making sure those using it were within the legal limit, Hannan said.