Some Illawarra train station platforms will be lengthened to fit the introduction of 10-car sets - but Unanderra won't be one of them.
This is despite it being the only shortened platform on the run for express services to and from Sydney.
The platform at Unanderra is designated SP6, meaning the first two carriages of an eight-car train stop past the end of the platform.
Commuters wanting to get off at Unanderra have to travel in the last six carriages.
Just before the last election, the government promised that all peak-hour express services between Wollongong and Sydney would be 10 cars.
This means that, when these trains stop at Unanderra almost half the carriages will be past the platform.
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A Transport for NSW spokeswoman said further planning for rail upgrades would include changes to platforms.
"Planning for future stages of the More Trains, More Services program is currently under way, including stopping patterns and fleet across different time periods," the spokeswoman said.
"This planning work also includes platform extensions for some stations to accommodate 10-car trains."
At this stage, the spokeswoman said only six stations would be extended - Port Kembla, Wollongong, Thirroul, Waterfall, Bellambi and Kiama.
Of those, only Bellambi is a shortened platform - like Unanderra it is designated SP6.
However, the spokeswoman suggested Unanderra may not be permanently left as a shortened platform.
"Detailed planning is underway on the stopping patterns for future services, and we may consider platform extensions at other stations," the spokeswoman said.
Measures in the New Intercity Fleet will improve safety for trains at shortened platforms.
"To maintain customer safety and allow trains to stop at stations with shorter platforms, the fleet will feature automatic selective door operation technology to make sure that doors only open when carriages are aligned to the platform."