Engineer Robert M. Sanchez pulled Metrolink 111 out of the Chatsworth station and was rolling north at 54 mph. About a mile later, he entered a restricted speed zone and throttled down to 42 mph.
Just ahead, on his right side, was a red light. It was a warning to stop so that an oncoming Union Pacific freight train could move off the main track and onto a siding. But Sanchez sped past the light and barreled over a switch mechanism that was supposed to guide the other train onto the side rail, according to federal investigators.
A quarter mile later, along a sharp curve in the tracks, the two trains collided at a combined speed of 83 mph. Sanchez never hit his brakes.
The job of sorting out what happened at 4:23 p.m. Sept. 12 now falls to a group of National Transportation Safety Board investigators led by Wayne Workman.
"It's about gathering facts and only facts," he said. "Our purpose is to investigate this and provide the best possible results."
Sanchez's actions are at the center of a federal investigation into the worst train accident in modern California history, which killed 25 people and injured 135.
Yet even as investigators uncover evidence suggesting Sanchez may have been responsible for the devastating collision, they are vowing to conduct a wide-ranging inquiry that will examine any number of possible causes and probably take a year to complete.
"The more narrow your investigation, the less clarity you have," Workman said.
He and other federal officials said in interviews this week that they plan to produce a detailed report that pinpoints a probable cause and lists recommendations to address factors contributing to the crash.
"It's a very deliberative, careful process," said agency board member Kitty Higgins, who responded from Washington, D.C., with the safety board's 17-member "Go Team."
The group, which includes rail experts, electrical engineers and psychologists, was on call when the Sept. 12 crash occurred and flew to Los Angeles the next morning.
Some of them, like Workman, are railroad veterans. The 59-year-old lead investigator is a fourth-generation railroad employee who started as an engineer and became a general manager of a rail company operating on the East Coast before joining the agency.
The NTSB is one of the smallest federal agencies in Washington. It has 400 employees, half of them dedicated to investigations. Typically, it investigates about 2,000 aviation accidents each year and about 500 other accidents on railways, highways and waterways.
