Federal officials have begun drafting safety standards for the nation’s subway and light-rail systems, three years after the deadly Red Line crash exposed vast gaps in oversight of trains that transport millions of people a day.

The Transportation Department has long regulated safety for airlines and Amtrak, but it had no authority to impose safety standards for subway and light-rail systems. The result, federal officials said, was a patchwork of rules and regulations covering systems from San Francisco to Washington.

Now, the U.S. government is carving out a bigger role in the safety of such systems. In the summer, Congress approved a measure expanding the authority of the Federal Transit Administration and strengthening the role of state monitoring agencies, such as the Tri-state Oversight Committee (TOC), the official safety monitor for the Washington Metropolitan Area Transit Authority.

“These first-ever federal safety standards will ensure we can bring the full force of our national transit expertise to help promote a culture of safety on our nation’s rail-transit systems,” said Sen. Barbara A. Mikulski (D-Md.), who led the push for federal oversight along with Rep. Donna F. Edwards (D-Md).

“My promises made are promises kept,” Mikulski said. “I will not rest until Metro is safe for those who work on it and those who ride on it.”

Federal officials met last month in the District to discuss the new rules, which will take several months to write. At a minimum, transit agencies will be required to have strategies for identifying safety risks, to employ a trained safety officer who reports directly to the head of the transit agency and to have training programs for employees responsible for safety. State agencies, such as the TOC, will be required to meet new standards and to be certified by federal officials.

The push for federal oversight was prompted in part by the growing number of derailments, collisions and worker fatalities on subways — notably the 2009 Red Line crash that killed nine people and injured more than 80 others. Federal officials expressed frustration that a 1965 law prohibiting federal regulation of subways was preventing them from taking necessary steps to ensure public safety.

“The law actually prohibited DOT and FTA from being involved in safety oversight,” Transportation Secretary Ray LaHood said. “The fact is there is no standard, no transit safety program that people nationally can look to as a model.”

LaHood said the goal of the new rules is not to drown local agencies in federal regulations. Rather, federal officials will focus on a common-sense approach that puts safety first, he said. Although the U.S. government will set minimum standards, it will not regularly monitor local operations unless state oversight is inadequate or nonexistent.

A spokesman for the American Public Transportation Association, an industry group that has published its own set of safety standards, said it is too early to know what the fiscal effect of the new standards will be. Subway systems in some cities, including Washington, Chicago and San Francisco, already have some elements in place.

“We think it’s a very safe industry,” APTA’s Mantill Williams said. “But at the same time, we’re open to making it safe and improving things.”

Metro officials said they welcome the additional oversight.

“It’s important that nationally we all play by the same rules,” said Richard Sarles, Metro’s general manager.

After the 2009 crash, Metro and the TOC were subjected to intense federal scrutiny. A federal investigation identified significant flaws in the authority’s safety practices, including safety problems that went uncorrected for years, and lent urgency to the lawmakers’ campaign for federal oversight.

The investigation also found that, at the time of the crash, the TOC had no full-time employees and a structure that hampered its ability to make decisions quickly. Those conclusions were reinforced in a Washington Post investigation, which found that the group had no enforcement powers.

As a result of that scrutiny, Metro has already put into place some of the changes that probably will be called for under the new law.

“We are in the lead in many respects,” Sarles said.

Metro revised its safety training program for workers in 2010. The authority also has a chief safety officer who reports directly to Sarles.

Still, this summer, the transit agency was dogged by a series of events that raised questions about safety practices. After a problematic train evacuation in College Park, Metro revised its procedures for such a situation.

In the three years since the crash, regional leaders have taken steps to strengthen the role of TOC. The committee now has three full-time staff members, a Web site and an office. The region’s three top transportation officials meet quarterly to discuss Metro-related issues.

James J. Benton, chairman of TOC since 2010, said the relationship between the committee and Metro, once antagonistic, is now cooperative. Benton said the committee and WMATA officials have developed a regular system for reporting accidents or incidents of note.

Metro officials said they have worked aggressively to correct a long list of safety deficiencies dating to 2006. Last month, officials announced that WMATA had closed out five recommendations issued by the National Transportation Safety Board, including two related to the fatal Red Line crash.

“For us, it’s safety first,” Sarles said.

LaHood endorses that idea.

“When somebody gets on Metro, they shouldn’t have to worry about whether the train is safe, whether the driver has received proper training,” he said. “Thankfully, now we’re going to have some kind of say in [how systems operate]. It’s something we take on very willingly.”