Auckland will have 17 new electric trains by 2019.

The Council has voted to purchase the new engines at a cost of around $198 million, down from an original estimate of $207 million.

The trains will run on the Southern Line, using the electrified wire system between Britomart and Papakura, and battery power between Papakura and Pukekohe.

Mayor Phil Goff said huge new housing developments are being built in the south, and better public transport options are vital.

"Anyone with experience of State Highway One and the south of the city knows that it's already at maximum capacity, and the third lane on the motorway will only help temporarily."

Mr Goff said it's a giant leap forward for Auckland.

"This is great news for public transport and great news for relieving some of the congestion problems that will otherwise be increasing in the south."

Councillor Mike Lee was the only councillor to reject the proposal.