Thousands of students are travelling long distances across Auckland to avoid their local schools.
Figures show that each day around 3,100 students in West Auckland travel to secondary schools in the central isthmus, with a further 800 leaving the area to attend North Shore schools.
South Auckland similarly loses a net 3,000 high-school students to central Auckland.
The volume of the movement is particular to Auckland. Morning trains are often filled with students leaving their area, and special buses move others out of their communities.
School holidays - which start today - cut the number of vehicles on Auckland's arterial roads by nearly 15 per cent, Auckland Transport said, with journey times reduced by 15 to 20 per cent.
Principals worry the problems facing schools in poorer communities are worsened because the more well-off students in an area go elsewhere - deepening the social divides between haves and have-nots.
"There is a serious problem ... in that too many parents don't believe they can get the education their children need at their local school," said Allan Vester, chairman of the NZ Secondary Principals' Council and head of Edgewater College in Pakuranga.
"This is reflected in property prices and doubtful practices by parents to get their children into more favoured schools."
A report delivered to Education Minister Hekia Parata this year outlined how the Ministry of Education planned to cope with Auckland's school-age population.
The report said: "[But] there are significant numbers of students, for example, travelling from South Auckland into the city and from West Auckland and Kumeu [and] Huapai to North Shore schools. If enrolment schemes were used to require students to attend schools in their local communities, this would shift the impact of the school-age population growth rather than addressing it."
Kelston Boys' High School principal Brian Evans said schools in the west were well aware of the issue.
"Having choice is great for parents but hopefully families look closely at their local options. Colleges in the west all have a uniqueness and special character of their own and achievement in the area continues to grow."
How do out-of-zone students enrol?
Such students have priority if they have siblings currently or previously at the school, or are children of former students. If applications exceed available places a ballot is held.
How are zones set?
A school's board of trustees prepares a zone in consultation with the Ministry of Education. The community and neighbouring schools must be consulted. The ministry has the final say.
What's a school zone?
Some schools have enrolment schemes to prevent overcrowding. This restricts guaranteed places to students living in a specified area, the school's home zone. About a third of NZ's 2,500 schools have such schemes.
5 things to do these holidays
The country needs clever inventors. Encourage your budding engineers to explore Motat's Invention Nation holiday experience. Until October 12. Normal admission prices. motat.org.nz.
Kids get to create a city from white Lego on a big table as part of the Cubic Structural Evolution Project at the Auckland Art Gallery. Also check out the kid-friendly Japanese movies in the downstairs theatre. Cubic is on until March 1, 2015. Taste of Japan, weekdays, 1.30pm, until October 10. aucklandartgallery.com.
Meet a kiwi
Auckland Zoo has a new behind-the-scenes kiwi experience to get up close to chicks hatched at the zoo as part of the kiwi recovery programme, Operation Nest Egg Kiwi Experience, Monday, Tuesday Thursday, Saturday (minimum age 6 years). Check out the Eye Spy holiday programme and daily young photographers' workshops. aucklandzoo.co.nz.
There's plenty of fun stuff around the airport. Ride the family-friendly mountain bike track designed by Auckland Mountain Bike Club , explore the outdoor sculpture gallery (maps from venturehere.co.nz) or visit Butterfly Creek and and Rocket Ropes. butterflycreek.co.nz, regionalparks, aucklandcouncil.govt.nz.