Federal election result a factor in splitting Canberra light rail stage two, Andrew Barr says

But he said he doesn't expect the federal Opposition to be "wreckers" and stand in the way of the full project.

Andrew Barr said fast-tracking work on the second stage of light rail between Alinga Street and Commonwealth Park would help get the project off the ground, rather than wait for federal government approval for the entire route to Woden.

Stage 2A would only involve negotiation with the National Capital Authority and ACT planning authorities, together with the Commonwealth Environment Minister.

Stage 2B - which crosses the lake and runs through the Parliamentary Zone to Woden via the State Circle - would also have to pass through the federal Parliament.

"What we're doing today will allow us to get on with a stage of the project that doesn't involve the federal Parliament," Mr Barr said.

But he said he doesn't expect the federal government to throw major roadblocks in the way of stage two light rail.

"We are yet to have a negative position from the federal government, he said.

"I would describe them as agnostic at this point. They have not said they are opposed.

"Prime Minister Scott Morrison has just won an unexpected victory ... and he wants to get things done, that's what he says publicly all the time.

"The other point I would make is that they won the last election and it doesn't mean they are in government forever."

Mr Barr said the Canberra Liberals' position was to be "blockers, wreckers and destroyers" but he did not believe the same could be said of federal government.

He said any risk of the project being stuck at Commonwealth Park was limited.

"There are time limited risks as well in this current federal Parliament ... they may say no but that doesn't mean that a future federal Parliament will always so no," Mr Barr said.

"If they did say no they would give a reason for that.

"We don't know whether or not they will ... but we would consider whatever reasons were put forward."

Former opposition leader Bill Shorten had pledged $200 million of federal funds to finance stage two of the transport plan, and would have been more likely to help fast track its approval.

"The circumstances changed with the federal election so now we are looking at a different way with getting on with the project," Mr Barr said.

The decision to split the second stage of the route to Commonwealth Park comes as senior economists suggested the ACT government take advantage of record low interest rates to fast-track infrastructure projects, as the ACT economy starts to show signs of decline.

The Chief Minister did not say how much the splitting of stage two would cost or whether it would be more expensive than completing it as one project.

It's estimated construction on the first stage of the route to Woden could begin as early as next year and be operational by 2023.

However, opposition transport spokeswoman Candice Burch said the government should justify their decision to split stage two.

"It's an extraordinary decision, the government doesn't know what it is doing and is making it up as it goes along," Ms Burch said.

"We are open in principle to the expansion of the light rail network but there's still a lot of questions to be answered by the government.

"We still haven't seen the business case or the cost [of stage two to Woden]."

Ms Burch said it was unlikely construction on the split stage would begin in a year's time.

"More than anything, the government didn't consider their options at the time and after the federal election they were too quick to rush to conclusions without all of the options in front of them," she said.