There’s a fine line between due diligence and unnecessary delay, and the state authorities who have custody of the environmental impact statement on the city rail project should make sure they don’t step over it.

The $5.5 billion plan to build an elevated rail line linking Kapolei and Ala Moana moved a bit closer to reality with the Federal Transit Administration giving its thumbs-up to the EIS. But it is by no means a done deal, with several key signatures lacking on the approval document.

Among them is the governor’s. Linda Lingle has raised objections to the project’s financial plan, which the city is revising as part of the standard process of federal review. City officials included the plan as a section of the EIS, though environmental rules don’t require the study to cover the financials; they said they hoped it would help expedite approvals by consolidating as much information as possible.

That approach seems to have backfired badly. According to staff at the Office of Environmental Quality Control, which oversees the EIS process for the state, it’s highly unusual, if not unprecedented, for a governor to hinge approval on a project’s financial plan; that aspect usually falls to the final approving agency — in this case, the FTA.

Nonetheless, the financial plan will be vetted the governor. This extra pause at least has a rational benefit for the taxpayers, who probably want some details at this stage on how they’ll be paying for the rail.

Also still outstanding, and crucial to a successful project, is a "programmatic agreement" among the FTA, the state Historic Preservation Division, the National Park Service, the Navy and the federal Advisory Council on Historic Preservation. This will be a complex accord that will serve as a guide to how construction should proceed with sensitivity to Hawaiian burials, historic sites and other complexities of the route.

Laura Thielen, who directs the state’s overseeing Department of Land and Natural Resources, said consultation among all those parties is continuing. This is not an issue that lends itself to shortcuts. Especially on contentious and emotional issues such as burials, it’s important to see that the i’s are dotted and t’s are crossed. Burial sites should be given due respect as a matter of conscience and legal prudence.

While it’s true that most of the burial sites are anticipated to be in the urban core, accelerating past this concern to an Ewa groundbreaking would invite lawsuits, conflict and expensive delays that would be better avoided with a careful legal agreement.

What makes far less sense is Lingle’s notion of conducting her own set of public hearings on the project. This is where she crosses the line to create unnecessary delay. There’s already a scheduled period for public comment on the EIS.

And those comments will be focused, as they should, on the environmental impacts identified in the EIS. An ad hoc governor’s hearing is likely to dredge up every critique and alternative that was reviewed and dispensed with in the city’s earlier planning stages.

It’s long past time to move beyond that point. A study dealing with a project this massive should be combed and discussed, but that discussion should stick to the issues that are still relevant, rather than going over old ground again.