The extra lending, almost $4 billion over the next five years, was announced at this week's state budget as part of a bid to stimulate jobs growth and economic activity.

Projections show the government's overall debt will grow by more than $3 billion to $9.5 billion in 2019/20, and up to $13.2 billion by 2022/23.

The borrowing has come under fire from the opposition and business groups, who claim crippling interest rate levels will burden the state in years to come.

But Mr Lucas on Wednesday defended his policy as a calculated move given the current economic climate.

"An assessment by the rating agencies which says that, in a $22 billion budget, this is a manageable level of debt is an important independent commentary," he said.

"We know that (a 1.66 per cent interest rate) won't continue forever so we'll lock in some long term debt and manage those sorts of issues over a long period of time."

In delivering the budget on Tuesday, Mr Lucas said the debt blowout and extra lending was necessary to fund an $11.9 billion infrastructure pipeline over the next four years and beyond.

Among the spend was an $834 million, four-year road safety package, which includes level crossing removals and intersection upgrades.

A further $1.1 billion was designated for regional road projects and transport infrastructure improvements over the next eight years.

The state's economy will grow by just over two per cent each year between now and 2022/23 and employment growth will be flat at one per cent.

Australian Associated Press