'Efficient' MPs hand PM poll and go home

It was meant to be three weeks of serious debate.

But an "efficient" parliament needed just one day to hand the Turnbull government a double dissolution trigger and abolish a road safety tribunal.

Senators and MPs began heading home on Tuesday, after the House of Representatives sat for three and a half hours and clocked off around 3.30pm.

The Senate, at least, was meant to sit for three weeks after Prime Minister Malcolm Turnbull deemed once-failed legislation to reinstate the building watchdog too important to let slide.

It too is expected to rise on Tuesday evening.

Much of what the 226 MPs and senators were recalled for a special sitting to achieve was wrapped up by adjournment on Monday night.

The prime minister had his double dissolution trigger after the Senate rejected for a second time a bill to reinstate the Australian Building and Construction Commission.

And owner-truck drivers were saved from a minimum wage rate decision of the Road Safety Remuneration Tribunal - which was also scrapped.

Those two events meant two other pieces of legislation - one to crack down on all unions and one to freeze the minimum pay decision by the tribunal - didn't need to go ahead.

Mr Turnbull acknowledged on Tuesday the parliament had been "remarkably" efficient.

But that's unlikely to save the Senate from being dissolved after the budget. Mr Turnbull confirmed he would request - at a later date - a double dissolution election for July 2.

Both houses of parliament can be dissolved if government legislation fails twice.

The efficiency left the lower house with very little to do on Tuesday, and the upper house tackling bits and pieces other than legislation.

Labor labelled the exercise a farce and evidence of chaos among government ranks.

Travel allowances and flights alone for MPs, senators and staff for three nights reach $787,384, according to figures provided by Labor.

But that's without costs of running the building, transport in Canberra and security, and some estimates suggest it could cost up to $1 million per day.

"We were called back, all flown in, in this urgent hearing ... and we're going home tonight," shadow treasurer Chris Bowen told reporters ahead of Tuesday's sitting.

Labor MP Tim Watts comically sang the theme song to US sitcom Seinfeld as he compared the parliament to the show written about nothing.

But for all their ranting, Labor was behind three futile attempts to suspend standing orders in the lower house on Tuesday - each taking over 15 minutes.

The opposition did get two goes at Question Time, giving Labor MPs the floor to grill the government on whatever they chose.

Just one day earlier, Governor-General Peter Cosgrove drove to Parliament House to officially open its second session in a grand display of formality.

It was the first time in 40 years the parliament had been prorogued - meaning all business terminated - other than for a general election.

After just two days of parliament's halls bustling with politicians and staffers, the building will go quiet once again until May 2.

That's a day before the Turnbull government delivers its budget - also in a special sitting, one week earlier than initially scheduled.