The golden sphere for pork-barrelling is surely transport projects. The winners are often concentrated in a single electorate, whereas the losers are taxpayers dispersed across the state or country. The pork-barrelling politicians can tell semi-plausible stories about jobs created and economic opportunities unleashed, and – best of all – there are great hard-hat photo opportunities.

But politicians are not supposed to spend public money to promote their private interest, including their private political advantage. This report shows that avoiding such conflicts of interest would be more straightforward if the federal government stuck to its national role, and did its due diligence before spending public money.

Pork-barrelling happens year-round, but there’s more of it during election campaigns, when promises are often particularly poorly thought-through. In the 2019 federal campaign, only one of the Coalition’s 71 transport promises valued at $100 million or more had a business case approved by Infrastructure Australia; for Labor, it was two projects of 61.

Federal pork-barrelling on transport projects favours electorally important states. Queensland and NSW, where federal elections tend to be won and lost, consistently receive more, and Victoria less, than can be explained by population, population growth, size of the road network, share of passenger or freight travel, or what it actually costs the state government to run the transport system.

Voters should demand better. Whichever party wins the 2022 federal election should strengthen the transport spending guardrails. The government, whether Coalition or Labor, should require a minister, before approving funding, to consider and publish Infrastructure Australia’s assessment of a project, including the business case, cost/benefit analysis, and ranking on national significance grounds. And the next federal government should also stick to its job: no more roundabouts, overpasses, or carparks, just nationally significant infrastructure on the National Land Transport Network.