Brisbane lockdown begins as G20 summit nears G20 legislation has been activated in Brisbane, granting police extra powers before the leaders' summit. THE lock down of Brisbane has begun. The Brisbane Convention and Exhibition Centre at South Bank - the venue for the G20 - officially became the city's first "restricted zone" yesterday. Black Hawk helicopters have also been buzzing over the city's suburbs as part of training exercises, with residents in Brisbane's north reporting low passes by the military vehicles in the early hours of yesterday. But the exercises, which started on October 21, have now come to a close. Defence officials had previously warned residents to expect to see up to five Black Hawk helicopters flying overhead "day and night" as part of the training exercises in the lead-up to the G20. Although the restricted zone around the convention centre officially came into effect yesterday, barricades had not been erected. The Brisbane Convention and Exhibition Centre is in lockdown ahead of the G20 summit. Pic: Robert Shakespeare/Getty Images Work is expected to start next week installing about 3km of 2.4m-high barricades around the centre. Motorists can also expect to have restricted access to streets immediately surrounding the convention centre, including parts of Glenelg, Merivale, Melbourne, Russell and Hope streets. Footpaths, however, will be kept open when possible. The centre has been under a 24/7 police guard since last week as it undergoes a facelift before hosting world leaders and media. It is two weeks out from the start of the summit, which opens on November 15. The first potential troublemakers have been placed on the G20 prohibited persons list in an attempt to stop protests turning violent. An international media centre the size of two soccer fields is being built. Thousands of barricades will also be installed around part of Brisbane's RNA showgrounds, Suncorp Stadium's bus terminal, South Bank's cultural precinct, and several hotels in Brisbane and at Sanctuary Cove on the Gold Coast in the lead-up to the summit. G20 operational police commander Assistant Commissioner Katarina Carroll said most of the barricades would be put up in the week leading up to the summit. "The barriers will form a vital part of our plan to secure venues and accommodation for the summit, and as the city starts setting up (for the G20) they will become highly visible,"" she said. A map showing restricted zones for the G20 at South Bank. Pic Mark Cranitch. Assistant Commissioner Carroll said the barriers would not only protect world leaders but also hundreds of police safeguarding them from any possible outbreak of violence. "Police will be both inside and depending on what the situation is, outside those barriers," she said. There will be a high-visibility policing strategy in place. Police, emergency services, and Defence are going through final preparations for the Brisbane G20 summit.