Grander projects such as a four-lane highway from Warkworth to Whangarei were possible but considered less likely, he said.
The announcement is due at 11am today.
With at least $6.8 billion of the $12 billion earmarked for transport, new rail projects are also expected with a third main trunk line from Quay St/Britomart station to Wiri Station, plus electrification of Papakura to Pukekohe considered highly likely.
Work on a busway for Auckland's North Western motorway and the extension of bus lanes on the Northern motorway towards Silverdale would make sense, Blair said.
He said he also expected to see a number of smaller projections around the country to improve safety on dangerous stretches of road.
Employers and Manufacturers Association Head of Advocacy and Strategy Alan McDonald said he did not expect to see a four-lane highway to Whangarei get the green light in this announcement, although he believed it was needed.
McDonald's wishlist for the upper North Island included both the Penlink and Mill Rd upgrade, although he felt the later was more likely to get the nod.
The third main trunk rail line for Auckland was a no-brainer because without it the City Rail Link wouldn't be fully functional, McDonald said.
But a more visionary approach would be to do a fourth line at the same time.
"A fourth main rail would also enable an express train service from the terminus at Puhinui to the City and complete the rapid transit link from Puhinui to the airport for a genuine fast, public transport option to the city."
In December Government announced that $6.8 billion would be allocated for new transport projects, with a further $1.2 billion for public hospitals, schools, the shift to more carbon neutral heating of public institutions and other regional initiatives.
Upgrades to New Zealand's water infrastructure are also expected.
That leaves a further $4 billion that can be allocated to entirely new projects and keep alive the possibility of a surprise in today's announcement.
Beyond the debate about the merits of specific projects, business groups say they want to see evidence of long-term strategic thinking in the announcement.
"We don't want to see an election lolly-scramble, said McDonald. "We want to see projects that are complementary and make sense for the whole country."
"Will [the Government] use projects to gain political capital in electorates in election year, or will it use the money to alleviate key problem areas and enhance transport networks between cities and regions to maximum effect?"
It was one thing to announce the new projects and another thing to get them completed in a reasonable time frame, he said.
Unfortunately the two year pause on starting the roads would likely translate to a much longer delay because the it had meant the loss of construction which would now have to be rebuilt.
The Government said in December time that not all of the $12 billion would necessarily be spent in the proposed five year time frame because of the challenges the increased construction programme could create for the already tight New Zealand labour market and the speed with which infrastructure firms are able to do the work.
"Our execution muscle has been left to go a bit flabby," Blair said. "But it is chicken and egg. If you give the industry certainty of a multi-year pipeline, and that it will survive political cycles, then business will invest and we will find the firms lining up to deliver it."