Sydney Metro tunnel standard unsafe: Labor

Sydney Metro passengers could suffocate and die if a fire breaks out in a tunnel because exits would be too far to reach, NSW Labor says.

The Australian standard ensures maximum cross-passage spacing of 240 metres but Sydney Metro insists its projects will employ the 500m European standard.

A cross-passage is a short tunnel that connects two parallel tunnels.

The passages are an important safety feature that allows people including emergency services personnel and passengers to move from one tunnel to the other in the event of an emergency.

Firefighters union representatives say passengers would be unable to escape in the event of a fire because the distance travelled to an exit would be far too long in a smoke-filled environment.

Massive infrastructure projects under way, such as the $6.5 billion Metro West and $11 billion Metro Western Sydney Airport, are failing to meet minimum Australian standards, Labor says.

"This could lead to a nightmare scenario where firefighters are unable to assist passengers in the event of a fire," opposition transport spokeswoman Jo Haylen said.

Doubling the cross-passage length means firefighters using a self-contained breathing apparatus will run out of air faster, undermining rescue attempts and putting both firefighters and passengers at risk.

"It's unacceptable for these projects to not measure up to Australian fire safety standards," Ms Haylen said.

"People's lives could end up being at stake."