MINNEAPOLIS — The Minnesota Vikings have produced a plan for funding road improvements necessary for their desired new suburban stadium, a piece of the $1.1 billion puzzle unaccounted for in the original proposal.

The Vikings and Ramsey County are asking the state to either issue a bond or an interest-free loan that would cover between $60 million and $81 million, which would be paid back over 30 years through stadium-user-based sales taxes and surchages on items such as tickets, merchandise, concessions and parking. A $20 per car sales excise tax in the county also would go to repaying the money.

Vikings vice president for stadium development and public affairs Lester Bagley revealed the plan in an interview Monday.

“We think it’s a proposal that gets the job done,” Bagley said. “Many of the road improvements that have been identified would serve a much broader purpose, whether or not the stadium is built.”

The stadium campaign essentially has been pushed into the background by the still-elusive state budget agreement that’s needed to avoid a government shutdown, but the Vikings have begun the final year of their lease at the Metrodome.

Lead owner Zygi Wilf has publicly maintained a commitment to keep the team in Minnesota, but developers in Los Angeles have inquired about a purchase.

The team and the county also identified available ancillary funding, mostly in transportation-related and site-cleanup grants, that could supply the remaining $50 million. Commissioner Rafael Ortega said he was confident that money could be secured.

The Minnesota Department of Transportation’s last estimate of the stadium road project was $131 million, $86 million for highway improvements and $45 million to improve adjoining roads and interchanges, but Ortega said Monday that figure is marked up. He said it’s based on a “30 percent contingency,” a liberal estimate of cost overruns and inflation. The team-county payment proposal for the roads is based on a range between $110 million and $131 million.

“Maybe even under $110 million,” Ortega said, pointing to a number of other construction projects in the county that have come in under budget. “It’s not like we’re building on swampland or something. It’s just reconstructing and rehabilitating existing highways.”

Kevin Gutknecht, a spokesman for MnDOT, declined comment on the commissioner’s cost contention.

Katie Tinucci, a spokeswoman for Gov. Mark Dayton, said the Governor’s office had not yet seen the proposal.

The Vikings struck a partnership with key county leaders calling for a $1.1 billion, 65,000-seat stadium with a retractable roof at the site of a former Army ammunition plant in Arden Hills, a suburb about 10 miles northeast of the team’s current home at the Metrodome in downtown Minneapolis.