A blunt message to Canberra to spend more on infrastructure might run into a simple problem of mathematics.
Grattan Institute chief executive John Daley says the Reserve Bank's call for more federal infrastructure spending could run into capacity constraints already hitting the road and rail construction sector.
"Not enough concrete, not enough steel, not enough stones from quarries, not enough engineers to design it, not enough people to hold the (road safety) paddle-pop sticks," he told AAP on Wednesday.
Reserve Bank Governor Philip Lowe cut official interest rates to a record low of one per cent on Tuesday, before calling on the federal government to spend more on infrastructure.
"This spending adds to demand in the economy and - provided the right projects are selected - it also adds to the country's productive capacity," Dr Lowe said on Tuesday night.
"It is appropriate to be thinking about further investments in this area, especially with interest rates at a record low, the economy having spare capacity and some of our existing infrastructure struggling to cope with ongoing population growth."
Finance Minister Mathias Cormann pointed to the coalition's infrastructure spending, which Mr Daley said was in line with the long-term average.
Instead he praised NSW and Victoria for doing the heavy lifting on infrastructure, particularly on the list of projects over $500 million.
"That used to be running at around $6-$7 billion a year. For the current year it's running at $15 billion," Mr Daley said.
"So that's jumped in just about three years, and it's forecast by Macromonitor to go to something like $23 billion or $24 billion by 2022.
"There are real questions about whether it is realistic to push anything more into that pipe over the next three years."
Instead, Mr Daley said if the government wants to pump money into the economy it should look at social housing like Kevin Rudd did in 2009.
Deloitte Access Economics partner Chris Richardson praised the states for continuing their infrastructure spending, but pointed to a different option to get more money flowing.
"Probably the smartest play for the federal government would be to raise unemployment benefits," he told AAP.
"You want dollars to ricochet through the economy, then you not only give them to the poorest people in the nation, but you remember the poorest people in the nation mostly live in the poorest regions and suburbs in the nation."
