Can we please bury this bad idea?

Among other things, a “Rooftop Highway would take away traffic — and hurt local businesses on state Route 3 in places such as Tupper Lake, seen here. (Enterprise photo — Aaron Cerbone)

We’ve said it before, and now it looks like we now have to say it again: A multi-billion-dollar “Rooftop Highway” between Watertown and Plattsburgh would be an enormous waste of taxpayers’ money — a veritable Bridge to Nowhere.

This old idea never dies. Now we’re hearing about it from Congress candidates — typical — and also because state officials are now taking another look at it as part of the Canton-Potsdam traffic study, a $2.5 million survey that has been going on since 2014.

Back in 2008, the state Department of Transportation recommended against building an interstate across northern New York. Instead, the DOT said, it would be more cost-effective to add some passing lanes and perhaps bypasses on U.S. Route 11 near Canton and Potsdam where the road gets most congested, especially for trucks. That’s what the Canton-Potsdam traffic study is supposed to be about — but now, according to North Country Public Radio, it’s looping back to review two studies on the Rooftop Highway: the 2008 DOT one that rejected it, and one from 2002 by the Development Authority of the North Country that recommended it.

We still call it the Rooftop Highway because that’s how it’s known colloquially. The DOT called it the “Northern Tier Expressway,” and some local advocates called it “Interstate 98.” No matter what you call it, it would be a federally run, four-lane, 65 mph freeway.

Like, for instance, the Adirondack Northway, I-87 — except that it wouldn’t have as strong a reason to exist.

The Northway, built in the 1960s, completed a direct interstate route between the largest city in the U.S., New York, with what was then the largest city in Canada, Montreal. Also, it’s a major corridor for tourism, one of New York’s major industries. Before the Northway, it was a two-day drive for New Jersey tourists to get to the heart of the Adirondacks. Our grandparents used to drive eight or nine hours on U.S. Route 9 to get from the New York City suburbs to Schroon Lake. Now that trip takes less than four hours.

The interstate system also did significant harm. It bypassed towns along old highways such as 9 and 9N — think Schroon Lake, Warrensburg and Port Henry. The business climate in those places never recovered from the loss of traveler traffic. Interstates dealt an even heavier blow to the railroad industry. Passenger train service to Tri-Lakes area ended right around the time the Northway was built.

What’s done is done, and there’s no doubt that the interstate system brought plenty of obvious economic benefits. But with the Rooftop Highway, the benefits would be minimal and the damage significant.

It would mostly follow Route 11, which already lets drivers go up to 55 mph, albeit slower through towns. Currently, according to Google Maps, it takes just under three-and-a-half hours to make the 158-mile trip from Watertown to Plattsburgh on Route 11 and the Military Turnpike. That’s an average of roughly 45 mph. Averaging 65 mph the whole way would shave off an hour, making the trip take two-and-a-half hours.

Not bad, if you need it, but how many people travel between Watertown and Plattsburgh? It’s not the highest-priority route for shipping or tourism. If you’re heading cross-country to the East Coast, it would leave you having to circumnavigate Lake Champlain and then travel on winding — albeit beautiful — roads through Vermont, New Hampshire and Maine. The people who choose to immerse themselves in America on the slower “blue highways” will choose the ones through northern New York, too.

In our experience, Route 11 is not very congested except through Canton and Potsdam. Otherwise, the demand doesn’t exceed the current road’s capacity.

“But what about potential demand?” proponents say. “Build it, and they will come.” Who? Sorry, but that’s too flimsy a promise for such a massive expense.

And yes, this would cost a fortune. More than a decade ago, the expense was pegged at more than $4 billion — with a “b.” Updated cost estimates are expected soon, but a federal government with a $20 trillion debt can’t afford to waste that much money.

Such a highway would also hurt small, locally owned businesses along Route 11, maybe replacing them with corporate chain stores at exits. That would be a step down, not up.

It would also turn a pretty country drive through the North Country’s unique villages into just another interstate haul.

Finally, it would do notable damage to the Adirondack economy. Right now, if you look on Google Maps for a route between Watertown and Plattsburgh, three come up — and the fastest is actually not Route 11 but state Route 3, running through Star Lake, Cranberry Lake, Tupper Lake, Saranac Lake and Saranac. It’s a tiny bit longer in miles, but because there are fewer towns, one can average 50 mph instead of 45 on Route 11. Combine this with the peaceful Adirondack forests and lakes, and plenty of drivers choose to go this way. But if they can save an hour on an interstate, many will. Much of the Rooftop Highway’s traffic would simply be taken from another part of the North Country.

It also means it would hurt small businesses on both of the North Country’s main east-west routes at once.

No way. Fix the routes through Canton and Potsdam, and leave it at that.