Officials of the Metropolitan Transportation Authority made public yesterday features of the transit agency’s burgeoning capacity to detect biochemical attacks in transit hubs.

The MTA has been stoic in the face of criticism that it has done little to secure the city’s transit system since September 11, 2001, a view bolstered by the agency’s secrecy over its plans. In the aftermath of last Thursday’s terrorist attacks in London, however, officials spoke of various means currently being tested throughout Grand Central Terminal to detect biological and chemical agents, including anthrax and sarin gas. Those plans, though, remain in their trial phases, and transit officials could not say when the technologies would be deployed throughout the system and at what cost.

Plans to implement a closed-circuit video surveillance system in the most heavily traveled and sensitive areas enter a new phase July 22, when three companies cleared by the Department of Defense will submit proposals for installing a communications network that would serve as the foundation for a more comprehensive security system.

Critics of the MTA have complained that it has not moved fast enough in spending the $591 million in federal and state money that was set aside for security in its 2000-04 capital plan.

Officials gave a fuller accounting yesterday of how the rest of that money will now be spent, though they offered little in the way of specifics.

The cost of biological and chemical devices would not come out of the $591 million in the capital plan, transit officials said. Of that money, the authority will spend half on detection devices, such as a closed-circuit television network, according to a manager in charge of the MTA’s security projects, Ashok Patel. He would not give details, however, of the type of technology that would be deployed initially across the system’s major bridges, tunnels, and subway stations.

An assemblyman, Vincent Ignizio, and a member of the City Council, James Oddo, both Republicans of Staten Island, called on the MTA yesterday to use the money to install security cameras in every train, platform, and station.

Though a contract for the closed-circuit network will be awarded in September, current plans would not include outfitting all of the system’s 468 subway stations with the technology, Mr. Patel said.

The remaining half of the $591 million will be allocated toward strengthening the physical infrastructure of the system’s most “critical” stations, such as Grand Central and Penn Station, against possible bomb attacks.

In the coming weeks, a construction company, John Civetta & Sons, will begin to erect bollards – posts that can prevent trucks from crashing into buildings – around the perimeter of Grand Central, replacing the concrete blockade that is in place around part of the exterior, an MTA official, who asked not to be identified, told The New York Sun.

Concrete barriers will also be constructed along the Park Avenue Viaduct, the roadway that winds around the terminal.

Plans to fortify protection at the commuter train station and to heighten video surveillance notwithstanding, last week’s attacks against rush-hour passengers riding London’s Underground underscored the ease with which would-be attackers can infiltrate a transit system. Some of the bombers could have detonated their bombs with as little as a cell phone, one reason New York transit officials disabled cellphone service in the tunnels until yesterday, when the MTA restored cellphone signals in the Midtown and Battery tunnels. The Holland and Lincoln tunnels, controlled by the Port Authority of New York and New Jersey, remain blocked to cell-phone signals.

The MTA is currently drafting a request for proposals from companies for a system to permit cell-phone use on subway platforms but somehow make it impossible as a means of remote detonation of bombs, a spokesman for the agency, Brian Dolan, said.

The MTA’s deputy chief of police told reporters yesterday that even with new technology aimed at improving security, the best protection against assailants remains vigilance by the riding public.

The deputy chief, Ronald Masciana, highlighted the MTA’s public awareness campaign, which was begun in 2002 with billboards that exhort: “If you see something, say something.”

“And in New York,” he said, “thank God, people are not shy. If it looks like a suspicious package, if it looks like suspicious activity, call us. That is the very first step.”

Mr. Masciana took reporters on a tour of three biological detection machines and one chemical detection machine currently being tested throughout Grand Central.

A 6-foot-tall beige steel box equipped with a stovepipe looks and – with its steady rumble – sounds like a furnace. The tall locker sitting in the hallway by Vanderbilt Hall is one of 12 units in the terminal fitted with filters that are analyzed every day by the Department of Health for biological pathogens.

Chained to a post on track 25, two metal boxes represent other forms of bioterror detection. A metallic cube hides an air-monitoring device known as a “dry filter unit,” which has been tested for more than two years – longer than any other detection technology used by the MTA. Next to it, the Autonomous Pathogen Detection System is a portable laboratory that can identify a biological agent within two hours of an attack.

“Keep in mind that all three are being tested now. We kept the first one going because that is the baseline the others grow upon,” Mr. Masciana said. “You can’t depend on lab results. You can’t depend on what the vendor indicates is best for you. … What you want to do is test it real-time to see how it operates.”

The biological detection machines are also being tested in Penn Station, Mr. Masciana said.

The one chemical recognition system that MTA police are now testing, known as the Protect system, is in Grand Central, where its chemical sensors are linked to a host of digital video cameras hidden in various parts of the building.

If an attack were to occur, a camera would home in on the site picked up by the chemical sensors. Police monitoring the video could relay to emergency workers critical information about victims, their health, the location, and how the area should be evacuated, while simultaneously sending the information to a federal laboratory.