Transport authorities have urged people to stay away from Sydney's CBD due to the ongoing siege in Martin Place.
Authorities have also advised people already in the CBD to follow the directions of emergency services personnel and transport staff.
People heading home from the Sydney CBD have been told to leave the city at their regular time but to expect delays.
Motorists and commuters in the city have been advised to plan their evening journey to take account of disruption to traffic and public transport.
Transport Management Centre spokesman David Wright warned commuters and motorists that changes to traffic and public transport could happen at short notice.
"Keep in mind in an event like this it's very, very common that things may close and change very, very quickly," Mr Wright said.
"So what you're seeing now may change in five minutes and we're doing our best to communicate that.
"But if you need to go into the city please try and change your planning because I don't think they're [going] away anytime soon."
Mr Wright said trains had resumed on the Eastern Suburbs and Illawarra line however trains were not stopping at Martin Place station.
"Of course the thing in an operational environment like this, we may also see lines like the Eastern Suburbs Illawarra line as well once again be partially closed at very, very short notice so obviously everything is being done to keep these lines open and the scenario like this we could have them closed very quickly," he said.
Road closures in the CBD
The Transport Management Centre said road closures in the CBD had changed as the police operation in Martin Place continued.
Elizabeth Street is closed northbound between Market Street and Hunter Street, and closed southbound between Hunter Street and King Street.
Macquarie Street remains closed in both directions between St James Road and Hunter Street.
Phillip Street is closed in both direction between King Street and Hunter Street.
King Street is closed in both direction between Elizabeth Street and Phillip Street.
All city-bound traffic travelling over the Sydney Harbour Bridge is being diverted via the Western Distributor and there is no southbound access to the Cahill Expressway, York Street or Harbour Street.
The Transport Management Centre said the Sydney Harbour Bridge, the Sydney Harbour Tunnel and the Cahill Expressway remained open, but northbound traffic on the Western Distributor could not use the Kind Street exits.
Motorists are being advised to use the Bathurst Street exit to access the Sydney CBD.
Motorists using the Cahill Expressway are no longer being diverted via the Domain Tunnel and traffic travelling city-bound on the Bradfield Highway are no longer being diverted via the Western Distributor.
City-bound motorists can use the Sydney Harbour Tunnel and the Gladesville Bridge as alternative routes.
City Road between Broadway and Cleveland Street at Chippendale has now been reopened in both directions.
Buses diverted in the CBD
The Transport Management Centre said buses entering and exiting the city were also being diverted and schedules and routes may change at short notice.
Buses on Elizabeth Street that normally run to Circular Quay are being terminated at Hyde Park, with services leaving the city starting from St James Station.
Newtown-bound bus services 422, 423, 426 and 428 that usually run via Castlereagh Street are operating on George Street instead.
Buses travelling in and out of the city from a southerly direction are terminating at Central Station.
Passengers are able to use tickets across all modes of transport.
For the latest traffic information visit www.livetraffic.com or call 132 701.
For the latest public transport information visit www.transportnsw.info or call 131 500.