Three volunteer actors trapped inside a small red sedan were cut free by firefighters with hydraulic rescue tools while police officers surveyed the scene, ambulance officers treated victims and WorkSafe inspectors began to look for evidence.

Attorney-General Simon Corbell said the exercise was designed to be as "realistic as possible" to ensure 12 newly recruited WorkSafe inspectors could operate under pressure and in co-operation with emergency services.

"There have been five fatalities at ACT workplaces in recent years and a number of incidents where workers have sustained serious injuries despite repeated safety warnings," he said.

"In response to the tragedies and the Getting Home Safely report, 12 new inspectors have been engaged by WorkSafe ACT, with several joining the new Major Investigations Team."

WorkSafe ACT commissioner Mark McCabe said the training exercise was beneficial for all involved and highlighted a number of skills inspectors could improve.

"Our inspectors wanted to collect all the evidence about how this actually happened but the emergency services staff were still working to get the people out of the car," he said.

"Some of our inspectors were a bit frustrated but that's the real world and saving people has got to be a priority."

Mr Corbell said the training exercise would ensure the inspectors would be able to hold responsible parties accountable after a workplace accident and operate under pressure.

"In order to effectively prosecute parties after a workplace incident, the Major Investigations Team has identified a number of key issues inspectors need to address including the handover at the scene, co-operation with responding emergency services and investigative methodologies," he said.

"When a workplace incident is reported, emergency services must first assist any victims and make the area safe before WorkSafe ACT and ACT Policing can investigate."

Mr McCabe said the 12 new recruits, which takes the total number of inspectors to 30, had already improved the strength of the agency.

"It's already paying off for us as we've been doing some blitzes lately, we've now got a stronger investigations team, and all of this is about building that experience," he said.

Mr Corbell said the government was committed to improving safety on construction sites in the ACT.

"High risk work, such as tasks involving work at height, or with or near electricity, continue to be the most dangerous activities on construction sites," he said.

"It is important companies and their site supervisors act with the highest level of vigilance when this type of work is carried out."