Newmarket's new railway station will receive its first trains this morning, but passengers face a giant step climbing on or off them.
The Rail and Maritime Transport Union believes the $35 million station's platforms are too low for elderly or disabled passengers, many of whom are likely to need help to step up more than a third of a metre to catch a train.
KiwiRail says the platforms have been built to a standard height of 750mm above the top of the tracks, similar to other new stations along the western line, and low enough to allow freight trains to pass safely by.
An exception is Britomart, where the platforms are 850mm above the tracks in the absence of freight trains.
But union industrial officer Scott Wilson says members believe the step up to catch trains at Newmarket will be higher than elsewhere.
"It is not exactly what you would expect for a new station," he said.
"It will be difficult for the elderly, infirm or disabled."
Trains have ramps for passengers in wheelchairs or on mobility scooters, but Mr Wilson said the low height of the platforms would make these difficult for rail staff to operate.
A rail employee said he understood only one class of railway wagon required platforms as low as Newmarket's.
"Why should the whole passenger network they are spending hundreds of millions on be compromised for one class of freight wagon?"
Auckland Regional Transport Authority spokeswoman Sharon Hunter confirmed the height of trains above the Newmarket platforms would be more than a third of a metre in some cases.
The floors of the older ADL and ADK diesel multiple unit (DMU) trains would be 374mm above the platforms.
Ms Hunter said Auckland had a mixed-use rail network, with maximum platform heights set by KiwiRail to accommodate freight movements.
But new electric trains due on the network from 2013 would be designed specifically for Auckland conditions, so could minimise stepping distances.
Ms Hunter also said trains would stop at specified points along Newmarket's platforms, to ensure ramps for disabled passengers were away from chokepoints, such as where zig-zag shelters were close to tracks.
The zig-zag seating is designed to given passengers ample shelter as daily patronage through Newmarket soars from 3500 now to an expected 17,000 within six years.
Newmarket Business Association chief executive Cameron Brewer intends being on the first train to pull in there from Britomart at 5.30am today and has offered to pay the $1.40c fare for others who may wish to join him.