Census NZ 2018 Travel to Work data. (Travel to Education data at the bottom of dropdown list). Each location dot is the centre of an SA2 area unit. Data is truncated below 6 people, for privacy reasons. So any specifc origin-destination (commute) which has less than 6 people using a particular mode, will not show. For example, if 5 people normally ride their bike from Te Atatu Peninsula to Wynyard-Viaduct, their trips are not displayed. If 6 people did, we would see a line representing them.