When she got to the Somme Parade side of the bridge, she carried onto the walkway under the bridge where she was approached from behind and indecently assaulted by the man she had overtaken on the bridge.
The victim swore at the man, who ran off along Somme Parade. He was seen by a witness crossing the road and running up Plymouth St.
Police have appealed for public help and say anyone with information should contact local police.
The appeal comes as police national prevention manager Eric Tibbott moved to calm fears over an abnormal increase in reported suspicious approaches to children and young people throughout the country in recent months.
"What we are seeing, over the last few months, is an increase in suspicious approaches to children and we can't pinpoint the cause of this increase," Mr Tibbott said. "Although, historically as we see increased publicity we see an increase in reporting," he said.
He said 92 abductions of people up to the age of 19 were recorded by police during the past year which was on par with previous years.
In most cases the offender was known to the victim. It's still extremely rare a person will be taken by a stranger in New Zealand.
Mr Tibbott welcomed people reporting what they believed to be suspicious, but said not all incidents had a sinister motive.
"We encourage people to report them, it's far better for police to spend some time and investigate something and find out it was just something like a miscommunication or breakdown, than someone not reporting it and we find there is someone specifically targeting children."
Only six of the reported 92 cases reported in the last year involved offenders who were unknown to the the victim.
"This is where we're trying to unpick the issue of custody related or custodial related incidents against this suspicious approach or somebody with an ulterior motive," Mr Tibbott said.
An emphasis on potential abuse or abductions by people unknown to them, historically referred to as "stranger danger", was outdated and a potentially dangerous concept which police have steered away from since the late 1980s.
The now used Keeping Ourselves Safe programme for schools focused on a behaviour-based rather than person-based approach, he added.
He also applauded the actions of those children who had been the victim of a suspicious approach in the past few months.
Last Monday, a 10-year-old boy was approached by a man in a black car in front of Upper Hutt College.
The man told the boy, "I need to take you home" - but the youngster asked the man for a password his mum had given him - when the man didn't know the answer, the boy ran home.
"That was a good example of how providing young people with education is helping to keep themselves safe," Mr Tibbott said.
"I'm really impressed with how we're seeing our young people looking after themselves."
He said police were working at a national level with the Ministry of Education to help ensure child safety, while local police have been conducting "high profile patrols" in areas which have seen suspicious approaches.
Mr Tibbott encouraged parents and children to have a plan in place when travelling to and from school, and to continue to report any suspicious behaviour to the school or police.
Recent suspicious approaches
April 10: A 9-year-old schoolgirl who was offered $100 by a stranger to enter their car near St Dominic's School in Blockhouse Bay. The student immediately ran off and told a teacher.
April 6: A female student from North Shore's Birkdale Intermediate School was offered a lift by man in a white van.
April 3: A 10-year-old boy was approached by a man in a black car in front of Upper Hutt College. The boy asked the man for the password, which the man didn't know, before running home.
March 29: A man with a dragon tattoo on his face tried to grab 14-year-old boy in Beach Haven on the North Shore and put him in his car.
March 9: A suspicious white van driven by a man parked near Birkdale Primary School on the North Shore.
March 7: A man in a white van approached an 11-year-old girl near Northcote Intermediate School on the North Shore.
February 28: A man tried to grab an 11-year-old girl on her way to St Heliers School, in Auckland.
Advice for parents and caregivers
• Teach your child how to get safely to and from school and other places they go - whether they walk, bike or go by bus.
• Make clear rules about getting home.
• Go to school with your child so that you can show them the safest route.
• Teach them to deal with hazards like narrow footpaths or busy roads.
• Meet the parents of children in your area and keep in touch.
• Teach the children to walk home together in twos or small groups, not alone.
• Make other arrangements if someone is away.
• Anyone who has an immediate concern for their safety should not hesitate to call 111.