There are few projects, if any, in Louisiana that could provide more economic benefit than the completion of Interstate 49 all the way to New Orleans.

Yet there are also few trickier questions politically than a toll that would pay for the highway between Lafayette and New Orleans.

We do not oppose a toll road solution, but we certainly understand the difficulties of getting tolls applied to a road that is, in parts of the Acadiana I-49 corridor, already up to Interstate standards and already open to the public free of charge.

The numbers are in from a state study of the feasibility of toll financing. Tolls starting at 18 cents a mile could pay from one-quarter to one-half of the more than $3 billion price tag to complete Interstate 49 South from Lafayette to New Orleans.

Given the very substantial cost of this project, and the backlog of at least $12 billion in unmet highway needs, it may be that tolls are a practical way to get the work done.

“Tolls are probably going to have to be an integral part of getting I-49 done, as long as people are getting what they are paying for,” said state Sen. Bret Allain, R-Franklin.

The business and political leadership of Acadiana is behind the I-49 South Coalition. The group is rightly touting the economic development of the region as one reason for the project.

Yet the experience of the New Orleans area, where bridge tolls were a contentious subject for decades, shows that this means of financing has its political hurdles.

The toll study looked at the financial feasibility of tolling the entire 145-mile stretch from Lafayette to New Orleans or tolling only segments within that stretch, with tolls collected in each area supporting work only in that portion of the roadway.

The study found that tolls collected along the entire 145-mile route could pay from 26 percent to 51 percent of the project.

Allain said any toll plan would likely focus on areas where upgraded construction is needed. Still, one takeaway of this study is that an investment of more revenues from either a higher gasoline tax or other state revenues is also necessary.

We hope that state politicians do not flinch from that prospect, as an I-49 corridor all the way from the Crescent City to the Arkansas line, and from there up to the heartland of the country, is a project that has enormous benefits for Louisiana.

Those benefits are garnered sooner if the state’s taxpayers step up their contributions, and that will be necessary whether or not there are tolls on portions of the highway.