The Bloomberg administration has moved methodically over the past decade to permit high-rise development in once low-scale, industrial neighborhoods from the Far West Side of Manhattan to Williamsburg, Brooklyn.

But the administration is now moving to rezone a 70-block area around Grand Central Terminal in densely packed Midtown for even taller skyscrapers, an initiative that it says is necessary in order for the district to retain its allure as a premier office district.

With the proposal now wending its way through the public approval process, the New York City Planning Department released a series of minor modifications to its own plan on Wednesday in an attempt to mollify some critics in the real estate industry.

The revisions provided little comfort, however, to those with stronger misgivings about the proposal, including community groups, preservationists and even some landlords who worry that the proposal is needlessly rushed and could result in a drastic increase in density in a neighborhood where the public transportation system is already overwhelmed.