Midland Highway upgrades are set to receive the lion's share of state road funding, with $50 million promised over the next five years.

Two-hundred million of Commonwealth dollars will also be tipped into touching up the national highway over the same time frame.

No information has yet been released identifying which sections of the Midland Highway will be upgraded first.

The Esk and Rokeby main roads and Murchison and Huon highways will also be the focus of road-fixing funds.

Uncertainty remains over the re-establishment an international shipping service between Tasmania and Asia following yesterday's budget.

The government was expected to announce which company would offer the service and when they would begin operating.

But beyond the $33 million put down on paper supporting the link over the next three years, no further details were made available.

Tasmania's ailing rail network is set to receive a $97 million cash injection over the next five years, with the money coming on top of about $120 million of federal funding.

Treasurer Peter Gutwein yesterday stopped short of flagging a forced merger between TasPorts and TasRail.

But Mr Gutwein said a review was under way to explore opportunities for "closer alignment of operations and investments" between the under-performing state-owned enterprises.

Irrigation was another big winner in yesterday's budget, with $30 million to be poured into water system investments over the next five years.

The money has been flagged for the second tranche of the state's irrigation project, with proposed schemes at Evandale, Scottsdale, Circular Head, Swan Valley and the Southern Highlands set to benefit.

A further $500,000 has been budgeted to improve and connect existing schemes.

The government will also spend $1.5 million to help farmers maximise their own irrigation investments.

The overall infrastructure spend was 12 per cent (or $170 million) more than was forecast by the previous government last year.