For more than a decade, a plan pushed by some South Bronx residents and transportation advocates has sat on the fringes of the State Transportation Department’s to-do list, in part because it would be a radical undoing: tearing down the Sheridan Expressway.

Although the plan has no real precedent in New York, advocates recite the benefits. They say it would ease traffic, improve neighborhood life and right a decades-old wrong committed by the master planner Robert Moses of building an unnecessary highway.

As other proposals for the Sheridan have been tossed aside, the idea to tear it down has improbably progressed to the center of the state’s rethinking of the highway, which runs only a mile and a quarter long between the Cross Bronx and Bruckner Expressways.

In the process, the Sheridan, a reliable thoroughfare for truckers and an eyesore for Hunts Point residents, has become something else: a battleground in a national fight to take urban spaces back from the automobile.