The city is moving closer to securing space in the Bronx for a second 911 call center, a long-delayed project that would serve as a crucial fallback if the primary site in downtown Brooklyn is knocked out.

The backup center has been in the works for more than a decade, even before the terrorist attacks of September 11, 2001, and a citywide blackout two years later made its necessity obvious.

In recent years, there has been a struggle to find the right site. That wait may soon be over.

City officials are in talks to lease more than 400,000 square feet of space for a second call center on the 42-acre site of a former state psychiatric hospital in the Bronx, and a deal may be close, sources say. The site is now the Hutchinson Metro Center, which is owned by Simone Development Companies. The company’s president, Joseph Simone, confirmed that negotiations are “very active,” but he would not discuss specifics.

The city has already budgeted $555 million in capital funds for the second center under a $1.3 billion overhaul of the emergency communications system that Mayor Bloomberg unveiled in 2004. Under that plan, the city’s police, fire, and EMT call-takers and dispatchers would be consolidated into an updated computer system at two duplicate sites. The sites would share the load of 30,000 calls that come in to 911 every day, and they would also back each other up – if operations at one center were knocked out, the other would be able to handle calls from the entire city.

Currently, the city’s primary 911 center is at MetroTech in Brooklyn, but call takers there must route calls to separate police, fire, and EMT dispatch centers across the city. As the city negotiates to lease space for a second center, officials are moving quickly to renovate the facilities at MetroTech and plan to consolidate dispatchers there even before a Bronx site is ready. Construction work is scheduled for completion this summer, to be followed by technology upgrades and installations, the acting commissioner of the Department of Information Technology and Telecommunications, Ronald Bergmann, told a City Council hearing last week.

For many, however, the key component of the 911 system is the second call center, known as the Public Safety Answering Center 2. Officials have considered several sites over the years, including a former reservoir in Ridgewood, Queens, and a location next to police headquarters in Lower Manhattan, which was rejected due to concerns over its close proximity to a potential terrorist target.

One lawmaker is losing patience with the delays. “We’ve been constantly told that progress is being made and yet ground zero is apparently moving faster than our backup 911 center,” the chairman of the City Council’s Public Safety Committee, Peter Vallone Jr., said. “I’ve made it crystal clear that the City Council will not stand for any further delays.”

Mr. Vallone said he may press Police Commissioner Raymond Kelly for a status report when he appears before the committee in a budget hearing today.

The president of the Fire Alarm Dispatchers Benevolent Association and a critic of the administration’s 911 system upgrade plans, David Rosenzweig, said he didn’t believe he’d live to see the second center built. Without it, a shutdown of the MetroTech site would result in mayhem, he said.

To administration officials, the situation isn’t nearly that dire. “We have backup systems in place, but this would be a major step forward in redundancy,” a spokesman for the city, Jonathan Werbell, said.

The city has been working to lay the groundwork for the second site with upgrades to circuitry and by making sure security holes are corrected, such as one in 2004 that allowed a Verizon technician to make a data entry mistake that shut down 911 calls from Brooklyn, Queens, and Staten Island for two hours.

Although the need for a redundant 911 call center in New York may be clear, a backup recently proved critical in a far less likely place – Lincoln, Neb. In September, a water main break flooded the city’s Hall of Justice, ruining elevators, furniture, and equipment and shutting down the city’s courthouse and law enforcement headquarters for four days.

The flood delayed court hearings and trials, but it caused no interruption in Lincoln’s 911 operations, also housed in the Hall of Justice. Dispatchers had already been sent to a nearby backup site, which had been built two years earlier. “During the flood, we did not miss one radio transmission. We did not miss one phone call,” the manager of the city’s 911 center, Julie Righter, said. The backup center, located seven miles away, operated for four months while damages at the Hall of Justice were being repaired.