Protesters have arrived, en masse, for today's hikoi over the Auckland Harbour Bridge

Hundreds are expected to take part in the protest against the Treaty Principles Bill, crossing the bridge in groups from about 9.30am.

NZTA has closed some lanes on the bridge and several nearby on and off ramps, and is warning people to expect significant delays over the course of today.

The Herald's Rachel Maher has been with protesters, preparing to march from Northcote's Onepoto Reserve.

She says one man told her he's spent thousands of dollars and taken his two children out of school to take part.