She said cars in one lane would often stop to allow the lollipop signs to go out, but cars in the opposite lane would continue. Eventually cars in the first lane would carry on again instead of waiting.
Ms O'Connor said police told her in the past there was nothing further that could be done in regard to the crossing.
"You're talking about nearly 300 children," she said, calling for more "in your face" warnings, or a set of traffic lights.
Mother Anna Scoullar-Jones said her husband had dropped their daughter off at school last week when he stopped at the crossing to let children put out the barriers and was tooted at by a car behind him. She said that had happened to her more than once.
She didn't believe traffic lights were the right option, as traffic was only an issue during certain times in the morning and afternoon, but said she would like to see lower speed signs.
She was aware of several children who were frightened to use the crossing because of the traffic.
She posted a complaint about it on the Wanganui Mummies Facebook page and received a large number of responses from people who were also unhappy.
Another mother, Mary Trevethick, said she had been abused by the same woman more than once for stopping at the crossing after dropping off her son, Hunter, 7.
Ms O'Connor said the school had to be fenced off three years back due to worries about traffic.
Acting Senior Sergeant Andrew McDonald said police would be getting in touch with the school to do work around compliance.
"Road safety and crime prevention is an important focus of the police, especially around children," he said. "We will take a very hard line with motorists who put our children at risk on the roads."
Sergeant Colin Wright said police would patrol around the school during school hours more frequently.
"If vehicles are driving around the barriers then it is dangerous and an offence," he said.
"If vehicles aren't letting children out to put their signs out this is bad manners.
"As long as the children don't go on to the road while traffic is behaving this way they should be safe."
Mr Wright said the children were trained not to go on to the road if traffic was within a certain distance from the crossing.
He said there was not a blanket law that all schools had a 40km/h speed around them, and that it was negotiable with the New Zealand Transport Authority.
However, he said: "The speed limit is already 50km/h and it is a state highway so I doubt whether the authorities will consider reducing it."
School Community officer Senior Constable Rob Condor had been working with the children and monitoring the crossing patrols.
He said he had seen cars driving around the barriers and believed it was a case of drivers not paying attention, rather than being impatient.
"People are totally oblivious to their surroundings," he said.
"Their behaviour does endanger children."
Mr Condor said it was important drivers were aware of the rules at crossings, and that they knew to stop for anyone waiting or coming up to cross, even if the stop signs weren't there.
He also said motorists weren't driving to the conditions, and that with so many children and other cars around, 30km/h would be a more reasonable speed.
Mr Condor said there were two other crossings in Totara St near a school where there were issues.
For Mrs Scoullar-Jones it was important the public was aware of the crossing.
"Is it going to take a child being run down at the crossing before people's eyes are opened and something's done?"