Thousands perched on picnic blankets and camped out in tents hours ahead just to catch a glimpse of the iconic Sydney New Year's Eve tradition, which was nothing short of impressive.

A rainbow waterfall from the Harbour Bridge served as a tribute to same-sex marriage, with 2018 to be the first year in which same-sex Australian couples can marry.

Beyond that, hundreds of different formations and colours from all over the spectrum shot into the sky to welcome the new year in the 12-minute spectacular that cost $7 million.

Dazzled, drowsy, and perhaps a little bit drunk, thousands turned away from Sydney's Harbour Bridge after the midnight fireworks on the first day of the year and set their minds on the long journey home.

With an estimated turnout of 1.5 million, transport authorities urged people to rely on public transport to get home safely, with road closures across the city.

All roads north of Goulburn Street in the CBD were closed, as well as citybound lanes of the Western Distributor and Anzac Bridge, and all lanes on the Harbour Bridge.

The Harbour Bridge and citybound lanes of the Western Distributor and Anzac Bridge were scheduled to reopen at 1.30am, but most roads were set to remain closed until 4am.

Additional late night services are running from the city on most lines, but trains leaving Central Station between 1am and 5am won't stop at Domestic Airport and International Airport stations.

Road closures are affecting buses, with those that normally travel over the bridge terminating at North Sydney, while buses in the CBD were running from Hyde Park, Wynyard and Town Hall until 1.30am.

Four secure taxi ranks were set up across the city, staffed by security guards to help people get home safely.

They are operating until 4am at Pyrmont Bridge Road, between Edward and Murray streets; Sussex Street, between King and Market streets; Liverpool Street, between Wentworth Avenue and Elizabeth Street; as well as Lime Street.

Limited ferries are running from Circular Quay following the fireworks, but they are expected to be very busy, while light rail services are running every eight to 10 minutes until 4am.

Police said several people were arrested in Sydney for minor offences, including offensive behaviour and affray, but that the night was largely trouble-free.

A 17-year-old teenage boy also sustained serious burns after a firework exploded in Cromer Heights about 11.40pm. He was taken to Royal North Shore Hospital for treatment.

While both the 9pm and midnight fireworks went off without a hitch in Sydney, crowds on Terrigal Beach were evacuated during the 9pm fireworks after a barge caught fire, forcing the two technicians to dive into the water to escape.

The technicians were rescued by passing boats and received treatment for minor injuries.