Sydney Metro has proposed using “squeezeways” for emergency access in its Metro West and Western Sydney Airport lines instead of the elevated walkways built in previous metro tunnels, prompting concerns that passengers may not be able to evacuate as quickly.
Squeezeways are walkways built into the bottom part of the round underground tunnels. They are about 80cm wide and involve the user literally squeezing along the side of a train stuck in the tunnel.
Guardian Australia has obtained documents that show Sydney Metro is actively considering the option, which was rejected on earlier projects, for the two newest metro lines: Metro West from the CBD to Parramatta and the line from St Marys to the new airport at Badgerys Creek.
The move appears to have been motivated by pruning costs and has caused consternation among staff, who fear the cheaper option will compromise safety.
“The project span is about 80cm, give or take, and a person who is not ambulatory will certainly have trouble getting though it,” one insider said.
“The issue from an engineering safety perspective is: we have no idea who proposed this idea and why our leaders are supporting it. Why are they deviating from an already approved design used on the City Southwest line?”
Sydney Metro said: “The squeezeway design is a low-level walkway to allow access along the side of the train designed for operational activities and emergency services only, including Fire and Rescue NSW – not for passenger use.
“Passengers would need to exit from the front or back of a stuck train,” it said.
The elevated walkways which have been elsewhere in the metro network are about 1m wide, are cantilevered from the wall at the widest part of the circular tunnels and have a hand rail. They can be accessed from all doors in the train.
“The squeezeway is to support the movement of tunnel occupants or emergency services alongside a stranded train or for regular access by maintenance staff,” one document explains.
It is described as a “value-based solution of modifying the low level side walkway within the tunnels”.
Last year Sydney Metro was forced to backtrack on a plan to build cross-passages every 500 metres instead of the Australian standard of 240 metres apart on the same two lines, after safety concerns were raised by Fire and Rescue NSW.
The greater spacing between the cross-passages, which link the main tunnels going in either direction, would have shaved $100m from the $27bn Metro West and the $11bn airport line.
The squeezeway proposal will require the approval of safety authorities.
Sydney Metro said it continued to consult Fire and Rescue NSW, adhering to the agreed formal process of engagement to ensure design specifications met relevant standards.
A number of metros around the world had used the same approach, including Munich, Singapore and Hong Kong, it said.
The documents appear to indicate that the cross-passage exits have already been designed low down to align with squeezeways.
Fire and Rescue NSW declined to comment specifically on the sqeezeway design, referring enquiries to Sydney Metro.
The acting deputy commissioner of Fire and Rescue NSW, Trent Curtin, said his organisation had a very important role in reviewing tunnel design in relation to the safe evacuation of occupants and safe access for emergency responders.
A spokesman for the Office of the National Rail Safety Regulator said the organisation was “actively monitoring this process” and when the designs were finalised the proponent would need to satisfy the regulator that it had addressed safety risks to the legal standard required.
“ONRSR is not a technical regulator with responsibility for approving designs. While we are aware of squeezeway solutions being used in major infrastructure projects overseas, each project and design is unique, as are any and all associated safety risks,” the regulator said.
The source inside Sydney Metro said a variation of the squeezeway design had been rejected by the ONRSR previously on a different line.
