It could take more than three months for Greater Wellington Regional Council and Kiwi Rail to fix the screeching made by the Matangi trains on the Johnsonville line.
Residents have complained since April about the metal-on-metal screeching sound the trains make.
Regional council rail projects manager Angus Gabara said the cause of the noise had only recently been identified.
"An acoustics report concluded that . . . as the train manoeuvres through a tight corner, the wheels are interacting with the top of the track in a way which is creating the squealing noise," he said.
The screeching was not detected during the testing of the Matangi trains, he said.
"Our initial noise monitoring indicated that the noise levels emitted by the Matangi were not dissimilar to that of the English Electrics.
"However, since the introduction of the Matangi on regular services, the noise has become more apparent."
Mr Gabara said it could take three months to work out how to solve the problem.
"We're currently identifying all possible solutions.
"This could well require some form of trials and could take up to another 12 weeks, finishing about the end of October 2012.
"When we've selected the best solution, we'll have an idea of how long it will take to implement," he said.
Khandallah resident Doris Heinrich said this was unacceptable.
"They have to make this a total priority and pull out all the stops.
"We can't live with it for 12 more weeks."
Mr Gabara said they needed to take time to test solutions so they did not cause more problems.
"We don't want a solution for this issue that risks creating other problems.
"For example, lubricating the track on a line such as Johnsonville, with a steep gradient and tight curves, could lead to slippage and braking issues."
- The Dominion Post