The Liberal MP has chosen to go against his own government for just the second time, calling for urgent action on the stretch of rail line between Helensburgh and Central.

In parliament this week, Mr Evans spoke of the 2013 timetable change and the effect on the northern Illawarra.

“That came at a cost to the small villages along the escarpment such as Stanwell Park, Coalcliff and Scarborough, where services were severely restricted, forcing those commuters to drive to the hub stations of either Thirroul or Helensburgh,” Mr Evans said in NSW Parliament.

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He also called for urgent planning to untangle the “spaghetti junction” that is the T4 Illawarra line, which includes different lines sharing the same rails or crossing over each other.

“I stand here asking for urgent planning for the future of the T4 and Illawarra lines to ensure that we have an efficient and flexible rail network from the south, which will provide commuters all the way from Bomaderry into the city with faster, more efficient travelling times,” he said.

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Speaking to the Mercury later this week, Mr Evans said transport officials had told him the rail line would be at capacity in only a few years.

“When they tell you from 2021 we’ll hit the wall and we’re at capacity and we can’t put another train on the line, that’s ringing alarm bells for me,” Mr Evans said.

“That’s telling me we’ve got to do something.”

He claimed that, without an urgent upgrade, the Illawarra would remain “the poor cousins when it comes to services into the city”.

“We’ve got some major issues on our line which, two decades ago should have been fixed but everyone kicks it down the road,” he said.

“But it’s now time we have to look at these seriously.”

He said drilling tunnels through the escarpment was “not ideal” due to geotechnical issues; instead the solution would be either laying another rail line altogether or duplicating sections wherever possible.

A Transport for NSW spokesman there were restrictions on what was possible.

“The T4 line is one of the busiest on Sydney’s rail network and is constrained by operational and infrastructure limitations,” the spokesman said.

“We are constantly striving to manage services in the best way possible, making changes and improvements where we can for customers on this complex part of the rail network and are investigating options to further improve services.”