MORE commuters would have to change trains to get to the city centre under a planned overhaul of Sydney’s train system that will attempt to make trains run more frequently and reliably.

The overhaul would mean commuters from a clutch of stations in Sydney’s west and north-west would lose direct services to the city, but they would be promised better and more regular services on the express line when they change trains.

The principles behind the planned redesign, which remain controversial inside the transport bureaucracy, are expected to be laid out in the coming weeks.

They promise an easier to understand timetable and simpler and faster train movements.

But they contradict a long-standing feature of Sydney’s train system that enables commuters on any station to get a direct service to the core of the city. Presently, only commuters on the Carlingford line cannot take a direct train to the city in the morning peak.

The redesign will aim to reduce the number of train lines feeding into the western line, which runs from the Blue Mountains through Penrith, Blacktown, Parramatta and the inner west.

The idea is that by merging fewer train lines into the western line it will be able to accommodate an increased number of trains in the morning peak.

Under one scenario seen by the Herald, trains on the Richmond line would no longer continue through the city, but turn south at Granville and head to Campbelltown. This would mean commuters on these trains would need to change at either Blacktown or Seven Hills for services to the city.

From Blacktown or Seven Hills, they would be able to transfer to express city services running every three minutes. The western line does not reliably operate services every three minutes.

Another feature of the plan is that trains that run to the city from Epping via Strathfield, picking up passengers at stations such as Eastwood, Denistone, and the apartment-heavy area around Rhodes, would terminate at Central.

Commuters on these trains with jobs in the inner city would have to transfer for Wynyard and Town Hall.

Multiple sources have told the Herald running this plan would require RailCorp to use more trains. RailCorp would have to retain old non-airconditioned train sets even as it receives more new Waratah trains over the next three years. It had planned to retire the older trains.

The Herald put its understanding of the rail plan to the office of the Transport Minister, Gladys Berejiklian. She said: “Transport for NSW is undertaking the most fundamental rewrite of the rail timetable in a decade to ensure we get the most out of the current network for customers.

“There is a lot of work to do and plans have not been finalised. The new timetable will be implemented late next year to improve service reliability and increase capacity,” she said.

The plan being worked on would also affect commuters at smaller stations west of Parramatta. Commuters from stations such as St Marys, Rooty Hill, Toongabbie and Wentworthville would have to transfer at larger stations such as Blacktown and Parramatta to make it to the city.

The Herald this month revealed the government is preparing to commit to a second rail crossing of Sydney Harbour as its next major train project after the North West Rail Link is finished about 2019.