WASHINGTON — An incident Monday in which one passenger was killed and scores were hurt when smoke filled a Washington Metro car during a chaotic rush hour commute has raised new concerns about Washington’s aging, troubled transit system.  The incident — the most calamitous on the Metro since a 2009 crash that killed eight riders and a train operator — was the most serious among a string of almost daily problems that befall riders of the system, like perpetually broken escalators, frequent delays and minor track fires. Earlier this week, the freezing weather cracked some aboveground rails in Virginia, causing extensive disruptions.  Riders, transit advocates and elected officials expressed concern and exasperation Tuesday with the response to Monday’s incident, including what appeared to be a chaotic evacuation of the affected train, which was headed from downtown Washington toward Virginia.  “Metro passengers deserve to know as soon as possible about Metro’s safety protocols for this type of incident, and those answers should be provided right away,” said Senator Mark Warner, Democrat of Virginia, in a letter to Richard Sarles, the Washington Metropolitan Area Transit Authority general manager and chief executive.  An ambitious capital plan to fix the system — the second-largest mass transit system in the nation — has been undermined by its unwieldy, multijurisdictional governing system in which everyone wants more services but few wish to pay for it, critics say.  The smoke that filled the car was probably abetted by an electrical phenomenon known as arcing, caused when the insulators on the third rail are somehow compromised through deterioration or debris, investigators said. But the federal authorities said it would take months to figure out precisely what had happened.  Eleanor Holmes Norton, Washington’s nonvoting congressional delegate, requested a congressional briefing for the region on the Metro’s safety and emergency response procedures. “The delay in terminating the third rail caused what appears to be an unnecessary delay in rescuing riders trapped underground and without any information,” Ms. Norton said in an email.  The Yellow Line train was at L’Enfant Plaza on its way to the Pentagon station about 3:30 p.m. Monday when smoke in the tunnel began filling the cars and the engineer was unable to back the train into the station, trapping some passengers in the cars. Many told reporters later that it had taken well over a half-hour for firefighters and the police to arrive. Witnesses described fear and panic as smoke billowed in and information was scarce, and some moved to evacuate themselves.  According to preliminary findings from the National Transportation Safety Board, electrical arcing — essentially like static electricity escaping from the third rail that powers the system’s trains — happened about 1,100 feet in front of the train.  “The train stopped in the tunnel,” said Peter Knudson, a National Transportation Safety Board spokesman, “but we don’t know if that was because of a loss of power, or if the operator saw too much smoke” to proceed. Investigators concluded their initial work at the scene Tuesday.  The source of the smoke remained unclear Tuesday as there was no fire present, according to investigators. “Something had to create smoke,” said Augustine F. Ubaldi, a railroad engineering expert. “Arcing is not unusual; arcing with smoke is.”  The key, he said, will be to find “what caused it to burn, and is this a fluke or systematic and what can get done to prevent it in the future within reason.”  The agency that oversees the rail line was largely silent Monday. But on Tuesday, Tom Downs, the Metro Board chairman, released an open letter to customers in which he offered “my deepest condolences to the family of the passenger who died yesterday following the incident on the Yellow Line.” He also promised that “once the cause of this incident is understood, we are prepared to take the actions needed to prevent this from happening again.”  The Washington Metropolitan Area Transit Authority, which serves 3.4 million bus and train riders over a 1,500-square-mile region, was created in 1967 by an interstate compact serving Washington, suburban Maryland and Northern Virginia. Its board has eight voting directors appointed by the Northern Virginia Transportation Commission, the Washington City Council, the Washington Suburban Transit Commission and the federal government’s administrator of general services. Funding comes from all four.  “This is the sort of thing that makes people roll their eyes,” Charlie Bryant, who commutes between Washington and Rockville, Md., said as the Red Line was delayed at a station briefly Tuesday night. He said riding the Metro was better than sitting in traffic, but he added, “There is always stuff out of service.”  Ricardo Wright, who commutes to suburban Maryland, also expressed frustration. “You think they’d have it figured out by now, but they don’t,” he said. “They keep raising the prices to pay for more malfunctioning”  A version of this article appears in print on January 14, 2015, on page A12 of the New York edition with the headline: For Washington Metro, a Death Is Rare but Problems Are Almost Daily. 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National Transportation Safety Board investigators were on the scene a day after an electrical malfunction filled a Metrorail tunnel with smoke and killed a woman.