Transit officials are again considering plans to dispose of old subway cars by donating the hulking metal cabs as material for artificial reefs to states along the East Coast.

The disposal effort would be a repeat of a program that transformed 1,261 “redbird” subway cars – with their distinct blood-red exterior – from underground vehicles into underwater abodes for plankton and other fish food.

This time, however, New York City Transit will have to look farther down the coast for takers of the cars. After receiving 250 subway cars in 2003, New Jersey enacted an eight-year moratorium on using subway cars, over concerns that asbestos in the cars’ floorboards and wall panels would leach into the marine habitat as the cars decomposed.

As a result of similar concerns, New York and Maryland, states with active artificial reef programs, remain opposed to using subway cars as reef material, according to the groups that manage those states’ reef programs. Neither state accepted the city’s subway cars in the program that ran between 2001 and 2003.

The need to discard 2,500 of the oldest subway cars will become acute beginning in mid-October 2006, when the first of 660 new subway cars for the system’s lettered lines come into service and storage space is filled to capacity, the assistant chief operations officer in the asset recovery department of New York City Transit, Michael Zacchea, told The New York Sun.

By then, Mr. Zacchea said, the transit agency will have decided whether to sink the cars or disassemble them for sale as scrap metal. He said turning the cars into reefs would be preferable, since there are economic and environmental benefits for the sport-fishing and maritime industries of coastal states.

The high cost of preparing cars for scrap yards and the low price the material commands on the market will probably make “reefing” old subway cars a cheaper alternative, just as it was between 2001 and 2003, when the authority says it saved $22 million by removing the redbirds’ wheels, windows, seats, and other grease-laden or floatable parts and pushing the 80,000-pound cars off barges along the coast.

“The program made quite a splash, if you will, from New Jersey to Georgia,” Mr. Zacchea said. If possible, he said, the same disposal method “would be our goal” for the next batch.

A New Jersey environmental group instrumental in implementing the ban – much to the dismay of that state’s sport divers and fisherman – has said the scientific advisory committee set up to monitor the durability of the subway cars and the effects of asbestos on marine life has met only a handful of times, stalling the research. “Its unfortunate,” the principal scientist for Clean Ocean Action, Jennifer Samson, said. “We may have an opportunity to discuss subway cars, but we haven’t answered the pertinent scientific and environmental questions from the first dumping.”

The artificial reefs are managed by the Army Corps of Engineers, along with the U.S. Environmental Protection Agency, which hands out permits that allow states to dump material – from old airplanes, tanks, oil cranes, and nontoxic construction rubble – onto the ocean floor to simulate the topography of naturally occurring reefs.

A biologist with the Army Corps, Edward Bonner, said the EPA has determined the amount of asbestos in subway cars was “way below” a level of concern. Because the asbestos was in water, it could not easily crumble and become an airborne hazard, as it can when it is used as insulation. The corps had not made durability a precondition for using certain materials as reefs.

Despite concerns over asbestos in New York and nearby states, Virginia, South Carolina, and Georgia have expressed interest in the subway cars, Mr. Zacchea said.

States have an added incentive to use the cars. In 2003, New York City Transit spent $6.2 million on preparations and shipping for nearly 500 cars it sent to Delaware. That qualified Delaware’s Department of Natural Resources and Environmental Control for as much as three times that sum in matching federal funds from the U.S. Fish and Wildlife Service, money to be used to help restore sport-fishing populations.

“The cars create value for the reef that is used to get matching federal funds,” the coordinator of that effort in Delaware, Lynn Herman, said. He said Delaware would be interested in receiving another lot of subway cars from New York in 2007.

New York City Transit is not the only source for artificial reef material, one reason it cannot pass the cost of furnishing the car shells onto the end user – though in the past, Southern states have agreed to pay the cost of shipping the cars south of Delaware.

Airplanes, Army tanks, old Navy ships, tugboats, and even part of the Robert Moses Causeway off the coast of Long Island have all been used to create artificial reefs. Still, with thousands of miles of coastline and the impermanence of even the hardiest materials in the sea, demand for materials to build artificial reefs is sure to persist.

“The ocean does have a way of consuming things sitting on the bottom,” the Army’s Mr. Bonner said.