Three companies want to join the state in building and operating a new cargo terminal at Mack Point in Searsport; only one will be chosen. How the Department of Transportation answers the “who” question is important, but just as crucial is the “how.”

Two of the contestants — Bangor & Aroostook Railroad and Sprague Energy — have piers and land at Mack Point and have shipped cargo from them for decades. The third, International Bulk Handling of New Hampshire, is a newcomer and a bit of a cipher. The DOT plans to keep the proposals confidential, review them in-house and pick a winner by the end of the month.

That would be a mistake. Eventually — June, actually — this project will go to the voters in the form of a bond issue for as much as $13 million. Eventually, voters will want proof that they’re getting the most for their money. Eventually, the details of the three proposals will come out. Since the deadline for bids came and went on Monday, since the bids submitted cannot now be changed, sooner is better than later.

B&A voluntarily has made its proposal public. It appears to be a good plan (and cheaper — the railroad says it can do the job for $9.8 million with a short payback period), but for now the public is left comparing apples to nothing. Sprague and IBH are private entities, they can decide for themselves what to release, but the DOT is public and should act accordingly.

Certainly, DOT staff engineers must review the proposals, but the scope of the review must be broader. This project isn’t just about nuts, bolts and pilings; it’s about a lot of other things, such as the economy of northern and central Maine and the ecology of Penobscot Bay.

Just a quick skim of the B&A proposal raises a few questions of the type that should be answered before the Legislature and the voters are presented with a done deal:

B&A now handles some of the cargo envisioned for the new terminal. If Sprague or IBH wins, will B&A then be competing against a state subsidy?

There now are two old, outdated piers at Mack Point, one owned by B&A, the other by Sprague, and the ocean bottom after 70 years of shipping can hardly be pristine. If one pier is picked for an upgrade, will it be the one needing the least amount of dredging, and if not, why not? It would be far better to address that issue now than in June, when regulatory agencies and environmental groups are accusing the state of not pursuing the least damaging option. Have the lessons of Sears Island been forgotten so soon?

The DOT has at its disposal a tool to get this important decision out of the office cubicles and into the light of day — the Maine Port Authority. After years of inactivity, this board was revived last fall by Gov. King to assist the DOT with port and rail issues. Mack Point is port and rail issues in one tidy package. Among the authority’s five members are non-DOT experts in economic development, international trade and commercial shipping. Throw in a representative of an established environmental group for good measure, let them work side by side and in public with department staff, and the DOT should get the answer it wants in June.