The Doctoroff plan for 10th Ave. station is something the city should start to seriously consider.

The first subway service expansion in 25 years opens Sunday with the inaugural run of the No. 7 line from Times Square to 34th St. and 11th Ave. All aboard this longawaited train! Doubly remarkable is the fact that New York City, and not the Metropolitan Transportation Authority, engineered the $2.5 billion project based on the vision of former Mayor Bloomberg and Deputy Mayor Dan Doctoroff.

They imagined that bringing mass transit to the far West Side wasteland would generate a building boom there, in turn producing tax revenues large enough to more than pay for the work. Boy, have they been proven right.

Just look at the forest of cranes on 10th Ave., and, more closely, at the thousands of construction workers swarming acres of steel. A new neighborhood, called Hudson Yards, rises in what had been thin air above tracks where Long Island Rail Road and NJTransit trains idle between runs.

Atop a soon-to-be-completed platform over the tracks, steelworkers are assembling a microcity that, at completion around decade’s end, will be occupied by 40,000 workers and residents.

They’ll be joined by consumers of food, fashion and culture, who now would be lucky to find a hot dog vendor on desolate 11th Ave.

A spur of the High Line will weave through the soon-to-be headquarters of style giants Coach and L’Oreal, which in turn will welcome New York Fashion Week when the event relocates to a permanent home in the Hudson Yards Culture Shed and central plaza.

To their north, the 90-story future home of Time Warner, CNN and HBO promises a cantilevered observation deck that will be the highest outdoor spot in the city.

And all this is in just the zone being built by one developer, Related Cos. Anticipating the area’s birth, other builders have staked fresh turf up 10th and 11th Aves. toward 42nd St., lining a new park.

Yet even though the No. 7 subway will run beneath, tenants and visitors will have access to only the one station at 34th St. The original plan called for a second stop at 42nd and 11th but was dropped for cost reasons.

And unnecessarily so, Doctoroff writes in the Daily News. He offers a solution that’s hard to dismiss — because it follows the playbook he and Bloomberg wrote to fund the extension to Hudson Yards in the first place.

He projects that the coming gusher in tax revenues would more than cover the expense of adding the station.

With the financing concept proven, Doctoroff is confident the city could sell more bonds to install the facility in a shell that awaits activation.

The proposal demands serious consideration, because thinking and acting big about the city’s future must not be a thing of the past.