The rebuilding of ground zero has received a boost following the largest insurance settlement of all time. An agreement yesterday between developer Larry Silverstein and seven insurers of the World Trade Center paves the way for $9 billion of new construction.

For the developer, the $2 billion settlement, which he must share with the Port Authority, is a significant source of cash at hand with which to start paying for his portion of the monumental rebuilding effort, set to begin in January.

The settlement, whose terms are favorable to Silverstein Properties, brings to a close a nearly six-year legal battle between the developer and the insurers of the World Trade Center. The settlement, reached in the early hours yesterday, brings the total amount the insurers of the site have paid to $4.55 billion. Several insurers had already paid Mr. Silverstein $2.55 billion.

On the same day that one legal battle over ground zero concluded, another one ramped up. For the first time, the city’s medical examiner, Charles Hirsch, said he is amending a death certificate of a woman to say exposure to dust from the September 11, 2001, attacks on the World Trade Center was “contributory” to her death.

The case involved Felicia Dunn-Jones, a government attorney who died at 42, four months after she was exposed to the dust cloud. The medical finding could prove a boost for a class action on behalf of thousands involved in the rescue and cleanup of ground zero who now say they are ill with respiratory ailments. Dr. Hirsch’s decision will likely be raised by the plaintiffs before the 2nd Circuit U.S. Court of Appeals, which currently has the case, Marc Bern, a lawyer whose firm, Worby Groner Edelman & Napoli Bern, represents nearly 10,000 of the plaintiffs, said.

Yesterday’s settlement with the insurers is a major victory for Mr. Silverstein, who was limited by court rulings to recouping no more than $4.68 billion.

A year after ceding responsibility for about half the site to the Port Authority, the settlement gives Mr. Silverstein the option of proceeding with fewer investors or banks behind him than had the insurance money still been tied up in court. It also provides some security for Mr. Silverstein, 76, and his continued leadership role in the project.

“This settlement is going to strengthen Mr. Silverstein’s position,” a managing director at Real Capital Analytics, Daniel Fasulo, said. “This will ensure the he will be the managing partner in this project.”

Mr. Silverstein will now use his share of the settlement, $1.12 billion, to help construct three soaring office buildings along Church Street. The Port Authority, which will recoup $880 million, will put the money toward the construction of the Freedom Tower, said to cost an estimated $3 billion.

The settlement was reached with the direct involvement of Governor Spitzer, who can now claim it as a success that eluded Governor Pataki.

The holdup on construction at the site has been largely due to wrangling over site plans, development rights, security measures, and financing. The dispute between Mr. Silverstein and the insurance companies has never called the redevelopment effort into question. Still, its conclusion seemed a great source of relief for everyone involved in the rebuilding.

The settlement, which Mr. Spitzer characterized as the largest in regulatory history, “will now assure that we go forward,” he said.

Absent a settlement, the Port Authority chairman, Anthony Coscia said, starting construction on the site would have been “like beginning a long journey with your gas tank half filled and hoping you are going to find a gas station somewhere along the way.”

At a press conference yesterday announcing the settlement, Mr. Silverstein noted that one year ago to the day he opened 7 World Trade Center, the only office building destroyed by the terrorist attacks that has been rebuilt.

“This agreement puts to rest the last uncertainty about the World Trade Center redevelopment, and will now allow rebuilding to continue moving full steam ahead,” Mr. Silverstein said in a statement.

The legal strategy of Mr. Silverstein, who leased the World Trade Center six weeks before the terrorist attacks was to argue that the two planes that struck the towers were two distinct events, allowing him to seek double his $3.5 billion in coverage. Lawyers for Mr. Silverstein were partially victorious, although lawyers for some insurers convinced a jury that the policy terms precluded Mr. Silverstein’s claim.

At the time of the settlement the task of appraising the value of the World Trade Center remained a chief sticking point, and Mr. Silverstein’s suit against the insurers seemed far from being resolved.

“We will be very happy to see this scar left by the terrorist attack finally healing,” the claims crisis coordinator at Allianz Group, Andreas Shell, said yesterday.

Allianz Global Risks was one of seven insurers that were a part of yesterday’s settlement (they also included Travelers Companies and Swiss Reinsurance Company). The share each company gave toward the $2 billion total is secret under a confidentiality agreement.

The vast majority of the settlement will be paid in 30 days.