An $80 million promise to speed up NSW train services could result in the closure of Picton, Tahmoor and Bargo stations.
The Coalition announced the multi-million dollar investment into the Canberra to Sydney route last Sunday, as a part of a $295 million investment in a fast rail network.
Wollondilly Council has written an urgent letter to Premier Gladys Berejiklian and Minister for Transport and Infrastructure Andrew Constance to clarify what this means for three of Wollondilly's train stations.
Wollondilly mayor Matthew Deeth said he had "grave concerns" about plans for the new straightened route between Menangle and Yerrinbool.
"We are seeking clarification on whether this means that Picton, Tahmoor and Bargo stations will be bypassed as identified in previous state government reports," he said.
"This could have a huge impact on the shire.
"To take out a number of public transport options would be a huge backwards step."
The state government's Future Transport 2056 plan first identified the proposal for a straightened route 12 months ago.
Cr Deeth said he was concerned that track straightening would further impact the ability of Wollondilly residents to access public transport.
"Effectively we are looking at a 50 per cent reduction of public transport in the shire," he said.
"These are the three main stations people use to access the city.
"Our only other options would be to travel to Macarthur stations which we know are already packed, or to drive on the M5 which is just insane during peak times."
Mr Constance could not provide an estimated timeframe for completion of the planned route, however he said the Liberal and National government was committed to start work in the next term of government.
"The transport bureaucracy is already working on it. Transport for NSW will work with our train operators in terms of NSW trains and Sydney trains and just get on with it," he said.
"We've done a lot of assessment work already on this line. There are constraints but sometimes just doing simple things can have a profound impact."
Cr Deeth said Wollondilly Council would advocate strongly for the shire to maintain all of its stations and to have the rail network in the region improved.
"Our population is expected to grow by approximately 100,000 people in the next decade," he said.
"If we were to lose three train stations I think this would be the worst plan we've ever seen.
"Our community needs to know the details of this plan with certainty - and if public transport links are going to be cut in our region they need to show us where the jobs will be.
"We have already had a poor commitment to job provision in the future plans for Wilton and Appin.
"The state government has plans for a '30-minute city', which is great, but what are the plans for Wollondilly?"