NEW YORK—The sheer volume of the work being done at the World Trade Center site in New York can be daunting.

There are 13 integrated “megaprojects” predicted to cost between $15 billion and $20 billion in total, approximately 435 subcontractors employing some 3,500 on-site workers, and more than 167,300 tons of structural steel—enough to build Yankee Stadium 15 times over.

And the work—much of it done by mid-market companies—is being done in a space no bigger than a few football fields, on top of three active subway lines, in a neighborhood packed to capacity with residents, commuters and tourists.

“It's one of the most complex redevelopment projects in the world because of the combination and co-location of so many separate projects,” said James Keane, general manager of inspection and safety risk management for the Port Authority of New York and New Jersey, which owns the site and is one of two principal developers in its rebuilding. “It's become quite a complicated and intricate formula that we're working with each and every day.”

One of the more effective ways the Port Authority and Silverstein Properties Inc.—the site's other principal developer—have gone about mitigating the ever-shifting constellation of safety, security and other risks associated with the WTC rebuilding has been to implement comprehensive incident, claims and observation-tracking systems for their respective projects on the site.

Since putting in place their Safety Management Systems Tracking Tool three years ago, risk managers for the Port Authority and Chartis Inc.—the agency's principal insurer for World Trade Center projects, including the 1,776-foot-tall tower at 1 WTC and the sprawling underground transportation hub—said they've have seen workplace injuries, reported hazards and workers compensation claims at the site “trending downward.”

“Prior to 2008, the World Trade Center was being handled like a normal construction site,” said Michael Castelli, a senior vp and World Trade Center site manager for Chartis. “You would see a whole bunch of claims come in, and there was really no control of that system.”

On most conventional construction projects, electronic site safety and performance records usually are segmented according to the individual insurers of the project, meaning most projects have separate databases for things such as workers compensation, property claims, injury and on-site medical reports, site safety observations and payroll. By combining all of these fields into a single, multichannel tracking system, Mr. Castelli said the Port Authority -has been able to more accurately assess and prevent injuries and accidents on its projects by enabling analysts to cross-reference corresponding entries.

“Our goal is to investigate every incident on the site, not only from a safety standpoint but from a claims standpoint,” Mr. Castelli said.

Mr. Castelli said combining payroll figures with incident reports, safety observations and insurance claims gives the Port Authority a much more thorough view of the projects' overall performance by tracking construction progress against workforce safety and spending trends.

“In the real world, as production goes up, safety goes down,” Mr. Castelli said. “What we've tried to do is find the point at which those two lines intersect, so that we're operating at peak efficiency while maintaining our safety performance. That's a challenge not only at this site, but across the industry on the whole.”

Similarly, risk managers at Silverstein Properties, itself a midsize company by virtue of its employee head count, said they recognized the need for comprehensive data monitoring when work began in earnest on the company's three skyscrapers in 2007.

By 2009, Silverstein and its broker, Willis North America, had developed through San Diego-based eSafety Systems a program that closely resembles the Port Authority/Chartis model.

“The powerful thing about the eSafety program is that it pulls everything on the site from a data perspective together,” said Robert Azarian, safety and loss control leader at Willis North America, noting that their system also tracks on-site medical incidents, insurance claims, payroll and site safety observations. “It's a living document that we're constantly reviewing and trying to make better.”

Like their counterparts at the Port Authority, Mr. Azarian and Shari Natovitz, Silverstein's vp of risk management, said the payroll metric becomes particularly important when combined with other performance indicators, “because it's part of the measure of how well they're doing from a safety standpoint.”

“If you don't know how many work hours you've got and what kind of payroll you're generating, you can't really correlate that with the number of incidents you're having,” Ms. Natovitz said. “We need those numbers to help us understand what we're seeing at the job site.”

Because of work delays in 2009 caused by financial disagreements between Silverstein and the Port Authority, Mr. Azarian said the company has yet to determine the actual year-over-year effects of the program. However, he said, predictive modeling based on work hours and claims data indicate “positive results.”

“The key thing about this is it allows us to close these incidents and these claims out much faster and more accurately,” Mr. Azarian said. “On a project of this size and scope, it's very easy for things to get lost in the shuffle if you're not tracking things.”