Transit officials announced a pair of plans yesterday to bring a modern-day amenity and greater security to the city’s transit system: a request for a company to design an underground cell phone network, and a $212 million project to safeguard the transit system against terrorist attacks.

In its request for proposals to be issued today, the Metropolitan Transportation Authority is looking to recruit a company to design, install, operate, and maintain a wireless communication network, so that subway riders can use their cell phones at all of the 277 underground stations.

The MTA specified that the cell phone network would have to work for all types of cell phones and carriers, though the network is required to provide service only at stations, and not in underground or underwater tunnels. The design would also have to prevent terrorists from using a cell phone to detonate bombs remotely.

Police officials have supported the idea, saying it would allow riders to call 911 during emergencies, alerting police to suspicious activity.

The cell phone network would bring the MTA much-needed revenue from the 10-year license issued to the winning bidder.

Cell phones have been used by riders in the 46 underground stations of the Washington, D.C., subway since 1994, when Verizon established an underground communications network. That network, however, allows only Verizon subscribers to make calls on underground platforms and trains.

The Metro, as the 29-year-old mass transit system in the nation’s capital is called, also has in place technology that detects chemical agents, a spokeswoman, Taryn McNeil, said. Such technology is not yet part of the multimillion-dollar project announced by the MTA yesterday to detect, monitor, and respond to potential attacks against the transit system.

Over the next three years, under a contract awarded to a leading defense contractor, Lockheed Martin, transit officials plan installation of more than 3,000 motion and perimeter sensors, intrusion detectors, and 1,000 closed-circuit television cameras, as part of an effort to monitor the extensive MTA system. That system includes 468 subway stations, seven bridges, two tunnels, two commuter railroads, and other sensitive sites.

The “integrated electronic security system,” as it was described by the MTA yesterday, could not, however, stop the kind of attack that occurred on London’s Underground on July 7, when men with backpacks detonated charges while riding deep below ground.

The system, touted as the first of its kind to incorporate satellite maps and video recognition software that can detect anomalies in live video feeds, such as abandoned packages on subway platforms, will not be deployed initially with devices that can detect explosives or biological, radiological, or chemical agents.

The MTA has not yet identified the type of technology it wants to use to detect such hazards, though the authority’s executive director, Katherine Lapp, said yesterday that the new security system is “modular in design,” so that the eventual technology could be incorporated.

The technology will not initially be used on any subway cars, trains, or buses.

The newly announced security project is the culmination of an 18-month-long assessment of the subway’s security needs.

Lockheed Martin, which the MTA selected over two rival bidders, will use technology developed by two subcontractors, Intergraph and Object Video, both based in Reston,Va., among other subcontractors, such as Slattery Skanska and ARINC, Inc.

Transit officials demonstrated yesterday how the technology would work, from the perspective of the “command and control” center to be operated by MTA employees. The demonstration consisted of a computer with four monitors.

Two monitors displayed the computer-generated maps and satellite photos used by some emergency-response and fire dispatchers to pinpoint the location of an emergency and its landmarks. A third listed the status of each sensor, and a fourth screen fed live “intelligent video,” which uses algorithms to determine when a passenger becomes separated from a package he may be carrying, sounding an alarm in the control booth that alerts employees to watch and analyze the potentially hazardous situation. The system also monitors and detects security breaches throughout the system.

In one scenario depicted yesterday, a video shows subway passengers disembarking at Penn Station. As the riders scurry up the stairs, one man stops, ties his shoes, looks suspiciously over each shoulder, and walks away, leaving his briefcase by the platform’s wooden benches. A flashing red box immediately surrounds the briefcase, alerting, in this case, the horde of reporters, photographers, and cameramen watching from an MTA conference room that a potentially suspicious package had been identified.

Under normal circumstances, the MTA would notify police to investigate the situation, Ms. Lapp said.

The cameras, which will cost about $1,200 each, and video software developed by Object Video are used elsewhere across the country to patrol unmanned ports of entry on the country’s borders, airports in Miami and Memphis, and the seaports of Jacksonville, Fla., and in the Everglades, a vice president of Object Video, Melchior Baltazar, said.

The contract awarded to Lockheed Martin comes after plans fell through nearly two years ago to use the Army and another defense contractor, Northrop Grumman, to design and manage the transit system’s security. The problem in October 2003 was the MTA’s unwillingness to cede control to the Army. Similarities between the plans, however, prompted criticism yesterday from the former deputy director of security for the MTA, Nicholas Casale.

He said the MTA “is back to step one” after spending $30 million on consultants “after the original plan was rejected and nearly three years wasted.”

Ms. Lapp said the complexity of the task – to secure an open, extensive, and aging transit network – was the primary reason that it took so long to establish a list of 5,000 security requirements the contractor would have to fulfill.

“While we were working very hard, very expeditiously, we wanted to make sure we got it right,” Ms. Lapp said.

Both Mayor Bloomberg and the chairman of the City Council’s Committee on Transportation, John Liu, Democrat of Queens, lauded the progress made by the MTA.