GET ready for a whole lot of roads to be dug up and people in hard hats to descend across Australia with the Federal Government said to be gearing up for an infrastructure budget.

Billions of taxpayer dollars are set to be splashed on new motorways, rail projects and runways when the Budget is handed down on May 8.

But transport boffins say infrastructure projects that really should get the green light are often overlooked. Politics can trump economic sense.

Treasurer Scott Morrison’s Budget is a crucial plank in the Coalition’s plan to claw back Labor’s lead in the polls.

Last week, Deputy Prime Minister Michael McCormack got in hot water when he compared the Treasurer to a Santa Claus who would hand down an “infrastructure budget” with “goodies” for everyone.

Mr Morrison slapped down the Deputy PM stating: “I’m not Santa Claus and I’m not bringing a bag of gifts in May.”

But, that didn’t mean there wouldn’t be any infrastructure projects to unwrap, he said: “The Grinch won’t be making an appearance either.”

Michiel Bliemer, a professor in transport and networks at the University of Sydney, said there was a simple reason politicians liked announcing big new roads, rail links and airports at Budget time.

“Building things is very visible so it makes the politicians always look good,” he told news.com.au.

Prof Bliemer said the Federal Government had traditionally been inclined to fund new roads while state governments leaned towards public transport. But with a tram-loving Prime Minister, the pendulum was swinging in the other direction.

Government body Infrastructure Australia produces a regular report on what it sees as the highest priority projects, the latest of which it released last month. This should guide government thinking.

But Jago Dodson, a professor of urban policy and the director of the Centre for Urban Research at RMIT University, said the headline grabbing “mega infrastructure projects” the governments smothered in cash were not always the ones that should be built.

“We’re starting to see both anecdotal and practised evidence there is as variation between what we might ideally see in terms of technical assessment of infrastructure and its economic viability, versus what political representatives do because of their own imperatives,” he told news.com.au.

Essentially, governments are prone to announce projects that make them look good — long-term planning be damned.

Exhibit one, Prof Dodson said, were big new roads like Sydney’s $10 billion WestConnex motorways, several phases of which are nearing completion.

“Major roads through constrained urban spaces are not a viable long-term approach. Most of your urban spending should be in rail with roads in the regions,” he said.

“A single rail line can carry 25,000 per hour while as a single lane of freeway holds 2000 vehicles, most of which have one occupant.”

Prof Bliemer said new motorways could even work against rail.

“Whenever you build a road, people get out of public transport and into cars and that is not actually what you want to happen,” he said.

WHAT’S ALREADY BEING BUILT

There’s a whole load of huge infrastructure projects that are currently in the works and fully, or partially, funded either by the states or Canberra. These include:

● WestConnex motorways, Sydney: $17bn

● North Connex motorway, Sydney: $3bn

● City and South East light rail, Sydney: $2-3bn

● Sydney Metro Northwest: $8.3bn

● Sydney Metro City and Southwest: $12bn

● Newcastle light rail: $300m

● Canberra light rail: $700m

● Level crossing removal, Melbourne: $2.4bn

● Metro rail tunnel, Melbourne: $11bn

● Tullamarine motorway widening: $1.3bn

● Brisbane airport second runway: $1.3bn

● Melbourne to Brisbane Inland rail: $8.4bn

WHAT PROJECTS COULD BE FUNDED?

Melbourne Airport rail link: $10bn*

Earlier this month, the PM pledged $5 billion from central coffers to connect Australia’s second busiest airport to the CBD, with the Victorian Government pressured to fund the shortfall. But Spring St may not want to play ball.

“I have a strong sense the Victorian Government is not totally convinced the project is worth pursuing,” Prof Dodson said.

They would probably prefer Canberra chips into the West Gate tunnel project, he said. But that isn’t even listed as a priority by Infrastructure Australia.

“We don’t even have a business case for the airport line and we have no transport plan so we don’t know if the line is of a higher or lesser priority than other lines,” he said.

East West Link, Melbourne: $4bn

“There is a possibility that the Federal Government may come back with an offer to fund the East West link, which would be strange given that it’s not supported by the Victorian Government,” Prof Dodson said.

Indeed, the East West Link motorway is one of the most expensive non-roads in the country. It cost taxpayers more than $1 billion in 2015 when Labor came to power, which had pledged to scrap a project that the previous government had brazenly signed up to just weeks before the election. Nonetheless, it has cropped up again in a number of future transport studies, including from the Victorian Government.

Western Sydney Airport: $11bn

A tonne of cash has already been poured into building Sydney’s second airport in Badgerys Creek, in the city’s west, including $5.3 billion from Canberra in the 2017 budget. Another $7 billion from state and federal levels of government has also been mooted for a rail link to serve the airport and build the so-called “Aerotropolis” surrounding it, designed to attract manufacturing, research businesses and academia.

WestConnex, Sydney: $17bn in total

This motorway project is so vast sections will likely open before work has even started elsewhere. With the M4 extension and the duplication of the M5 nearing completion, the next announcement could be some serious dollars for an underground connection between the two.

Brisbane Metro: $1bn

Sydney is building a metro, Melbourne is building a metro tunnel, now Brisbane wants a metro too. But truth be told, Brissy’s “Metro” is actually a busway with vehicles that look a lot like trams; but are, in fact, fancy buses. The high frequency service would link up the CBD and inner suburbs.

The Queensland Government would also like its $5.4 billion Cross River Rail Link project to be given some dosh. But that could be wishful thinking.

OTHER PROJECTS THAT COULD GET A BOOST

The upgrade of the M4 motorway from Parramatta, in Sydney’s west, to the Blue Mountains is listed as a project of the highest priority by Infrastructure Australia. In Queensland, the Beerburrum to Nambour rail line upgrade would decrease north coast rail congestion. South Australia’s most pressing project is the Eyre Iron Road Infrastructure Project. In WA, the Mitchell and Kwinana freeway upgrades also merit a mention.

* Dollar amounts are total project figures that could include funding from a number of sources including the Federal Government