New York City residents who live in low-lying areas should voluntarily start moving out on Friday, before Hurricane Irene is expected to hit, Mayor Michael Bloomberg said on Thursday.

Otherwise, they risk getting stuck because the mass transit system that millions of New Yorkers rely on might have to be shut down on Saturday, he said at a televised news conference.

New Yorkers should start feeling the effects of Hurricane Irene early Sunday morning. It is expected to hit the city of 8.4 million people as a Category 1 storm, the lowest ranking of major storms.

The mayor made it clear that residents in coastal areas, such as Battery Park City on Manhattan's southern tip, Coney Island and the Rockaways, should not linger until he issues an evacuation order because doing so could endanger emergency workers.

Bloomberg, a political independent, said he would decide by 8 a.m. on Saturday on whether to order about a quarter of a million coastal residents to evacuate.

City shelters will open by 4 p.m. on Friday, Bloomberg said.

To keep traffic flowing, public permits for events -- fairs and block parties, for example -- were revoked for Sunday except in coastal Zone A areas, when they were canceled for Saturday.

On Thursday afternoon, New York Governor Andrew Cuomo declared a state of emergency, which helps the state tap aid from out of state and the federal government.

Even inland areas are expected to be struck by Hurricane Irene, now on course to hit eastern North Carolina on Saturday as a major hurricane, U.S. National Hurricane Center Director Bill Read said on Thursday. The storm then will travel up the U.S. Eastern Seaboard north from there.

SUBWAYS MAY BE SILENCED

New York state's Metropolitan Transportation Authority, which runs the city's buses, subways, and suburban commuter lines, could remain shut through sometime on Monday, Bloomberg said, advising employers to prepare.

The mass transit system is the nation's largest, serving 8 million people a day.

The subways might have to be shut because surging sea water could damage the equipment. Commuter railroads could not only flood, but strong winds could knock down their power lines.

MTA Chairman Jay Walder said the mass transit system must shut if winds top 39 miles per hour.

It takes us a minimum of eight hours to shut the system down, he said.

Some Long Island service is already being modified.

The Hamptons special trains for tomorrow are canceled, he said.

Walder said to the best of his knowledge that such a shutdown was unprecedented.

The MTA also runs major city bridges and tunnels. Whether bridges must be closed will be made on a case-by-case basis, he said.

ELDERLY AND FRAIL TO HIGHER GROUND

In New York City, nursing homes, hospitals and senior centers in the low-lying areas must evacuate -- unless the city and state gives them permission to stay -- by Friday night.

For those who are homebound and not as mobile as we would like (them) to be, we would strongly urge that they move tomorrow, Bloomberg said, because the wheelchair-accessible buses cannot handle them all.

The mayor cautioned that the storm's path was hard to predict with any precision.

Instead of going across the eastern portion of Long Island, it now appears it will (hit) the eastern area of Queens, the mayor said, referring to the borough that borders Long Island's Nassau County.

The five hospitals in the low-lying areas are already canceling and rescheduling elective surgery, and moving patients to hospitals located on higher ground. For more details, see: gis.nyc.gov/oem/he/index.htm

New York Storm Michael bloomberg Michael bloomberg