KiwiRail says it has implemented several recommendations after an incident that exposed workers to toxic fumes in in New Zealand's longest rail tunnel and denies there are systemic safety problems.
The Rail and Maritime Transport Union says an incident in which contractors in the Kaimai Tunnel were nearly overcome by toxic gas is a sign of health and safety problems in the rail network.
In August last year, the men were exposed to fumes in the 8.9km tunnel in Bay of Plenty.
The union says they were exposed to carbon monoxide and nitrogen dioxide, and that petrol-driven equipment was being used in a tunnel which has no ventilation system.
Union general secretary Wayne Butson said when gas monitor alarms went off some of the men did not leave the tunnel straight away.
Five of the workers, who were about 3km inside the tunnel, became weak and disoriented and when they did make their way out, they went to the far exit by mistake, he said.
Mr Butson said a KiwiRail worker found them by chance as they were lying on the ground, trying to regain their breath.
He said they would have inhaled a cocktail of fumes from compressors, generators and other machinery mixed with dust which would have led to nausea, disorientation and giddiness. "That would have caused a great deal of distress and panic amongst the workers."
Mr Butson said some of the contractors had not been trained in tunnel gas procedures and did not have the right gas masks.
However KiwiRail's infrastructure and engineering general manager Rick van Barneveld said the men left the tunnel by vehicle.
He said the reason they went to each end of the tunnel was not because they were overcome by fumes and disoriented, but because 20 metres of rail tracks had been lifted and vehicles had to leave in those directions.
He told Radio New Zealand's Morning Report programme the company rejects the notion that the incident indicated a systemic health and safety problem.
Mr van Barneveld said the level of carbon monoxide in the tunnel was not sufficient to make the wearing of gas masks mandatory.
KiwiRail said six contractors were trained in tunnel dangers by a KiwiRail official and the other four were supervised by another trained individual. The company said a new policy since the incident will require everyone to be trained in tunnel dangers.
One contracting firm, Concrete Solutions, is not commenting on this case. Another, Abernethy Civil Ltd, will say only that its staff are trained, and anything needing remedying has been remedied.
Lawyer Hazel Armstrong specialises in health and safety and was asked by the union to investigate the Kaimai Tunnel incident.
She said the gas exposure could have been avoided if recommendations from an earlier review of Otira Tunnel by the union and KiwiRail been implemented.
"Although the tunnels are different many of the risks are the same - which is that if you don't have good ventilation fumes can build up."
The union also objected to the fact that the men were not checked for poisoning after the exposure and were instead taken by a KiwiRail manager for some food and drink to recover.
Mr Barneveld said the recovery procedure for an incident of this level is rest, fresh air and food and drink. KiwiRail has now changed the procedure, however, and anyone affected in future will have a medical test.
A management-union inquiry will consider further improvements and its terms of reference are being finalised.