Within hours of the CSX train derailment that killed two young women in Ellicott City early Tuesday, investigators from the National Transportation Safety board were on the scene to determine why it happened.
When tragedy strikes in the nation's skies or on its roads, rails and waterways, the NTSB is where the nation looks for an explanation of what went wrong, but answers seldom come quickly.
It could take months or even years before the independent federal agency reaches a final conclusion on the cause of the train derailment that ended with Rose Mayr and Elizabeth Nass, both 19, buried in coal on a railroad bridge in the historic downtown.
Jim Southworth, the NTSB's lead investigator, said the agency has not determined the cause of the accident. He said its experts had just begun the painstaking process of examining every aspect of the incident.
"It is a slow process, but it is very productive," he said.
Experts interviewed by The Baltimore Sun also were reluctant to speculate about what might have caused the Ellicott City derailment based on news reports. Derailments can be caused by problems with the tracks or rail bed, excessive speed or defective equipment.
James Remines, a former NTSB investigator who retired two years ago and now lives in Gambrills, said Southworth's statement that the train operator had not applied the air brake but that the air line had ruptured indicated the emergency brake activated only after the derailment had started.
Remines said that if the engineer did not apply the air brake, that would be "a clear indication the victims had no role" in causing the derailment.
"They just happened to be in the wrong place," he said.
John Samuels, a retired senior vice president for operations at Norfolk Southern, said the women were probably "victims of circumstance."
Samuels said a broken air brake line will trigger emergency braking that can cause a derailment. If the derailment comes first, he said, the cars typically fold over one another like an accordion, which separates the air lines, automatically activating the brakes.
The NTSB has not reached a conclusion about whether the women's presence contributed to the derailment, Southworth said. Like all other aspects of the crash, he said, that is still being investigated.
The NTSB seeks to produce not just answers to the questions of how and why a calamity occurred and who was responsible, its mission also is to determine what lessons can be learned to help prevent similar accidents in the future.
Over time, those answers have led to numerous safety improvements in aviation and on railroads, intercity buses, transit lines, ferryboats and other modes of transportation.
In the Ellicott City case, the agency is expected to examine many possible causes — or contributing factors — to a derailment that also blocked traffic and disrupted commerce in the Howard County seat.
Among the factors NTSB investigators will look at are the track conditions along the Old Main Line — one of the oldest railroad rights of way in the United States.
"We will do an exhaustive examination of track maintenance," Southworth said.
Investigators will take the torn-up track apart and piece it together on a flat surface, he said.
Samuels said teams from the agency and the railroad will work their way miles up the track from the scene of the derailment.
"They look for any defects, any indication that the rail has been pocked by something that has been broken," he said.
Other factors the agency will consider are possible equipment failure, how the crew handled the train and weather conditions before the accident, said NTSB spokesman Eric Weiss. The agency will inspect the derailed cars and comb through debris for clues. Crew members will be tested for drug use and quizzed about whether they were fatigued or using cellphones — contributing factors in previous train crashes. Metallurgists will examine rails, wheel assemblies and other equipment for signs of damage.
Russ Quimby, a retired NTSB railroad accident investigator who now operates a rail safety consulting business in Omaha, Neb., said the agency typically arrives with an investigator in charge and a group of team leaders with different areas of expertise.
"You'll have a track guy. You'll have a signals guy. You'll have an operating equipment guy," Quimby said.
A psychologist will examine possible human factors, he said.
Three crew members were aboard the train at the time of the derailment — a conductor, an engineer and an engineer in training. Southworth said the trainee was operating the locomotive at the speed limit of 25 mph. He said he planned to interview the crew late Wednesday.
Historic Ellicott City's tightly confined streets make it more difficult to conduct the investigation, Southworth said.
"This is a well-orchestrated industrial ballet," he said. "It is a uniquely challenging location."
The NTSB team will take as long as it needs to gather evidence at the scene, Quimby said. Investigators typically spend five days to a week at an accident scene — even longer for something such as a major aviation disaster — and then take their investigation into the laboratories, he said.
Interested parties such as railroads, unions, manufacturers and regulatory agencies — in this case the Federal Railroad Administration — will be invited to participate.
Investigators then will begin the painstaking process of compiling the reports from the various team leaders into a draft finding of a probable cause that eventually must be approved by the agency's five-member board of presidential appointees.
The time it takes for the agency to reach its conclusions can be frustrating to those who want instant answers.
"Everybody wants to know yesterday what happened," Quimby said.
In another deadly transportation accident, the sinking of the water taxi Lady D in Baltimore harbor on March 6, 2004, it took two years for the NTSB to produce its final report, which placed much of the blame on the Coast Guard for the overloaded conditions that contributed to the boat's capsizing.
Others have taken longer, but those are relatively unusual.
"We generally say a year or 18 months," Weiss said.
Some retired NTSB employees say the agency is taking far longer than it once did to issue reports.
"When I left, it was frustrating to get the reports out because you had so many levels of reviews," Remines said.
Quimby, who participated in the investigation of several major train disasters in Maryland during his NTSB career, said he thinks the agency takes "an inordinate amount of time" to issue reports.
"Political sensitivity has become more and more involved, regardless of which party is in power," he said.
But the agency doesn't always wait for the final report to identify problems. Quimby said that if the NTSB discovers a condition that it believes poses an imminent danger, it will issue what is called an "urgent recommendation" without waiting for a final finding of probable cause.
That's what it did in the case of the Lady D, when it recommended in December 2004 — more than a year before its final report — that the Coast Guard revise its weight limit table for pontoon boats to more realistically reflect the weight of the average American.
In the Ellicott City investigation, it is far too early to know whether the agency will issue such recommendations. An early indication of what the agency is focusing on could come when the agency releases its "docket" in the case — a compilation of testimony, laboratory reports, maintenance records and other hard data that generally is made public before the agency announces any conclusions.
Quimby said that while the NTSB may be slow in making its final report, the agency is generally accurate.
"The safety board is generally pretty good at getting to root causes," he said.