"We can say with confidence that the signal system was working," National Transportation Safety Board member Kitty Higgins said as she summed up the early stages of what promises to be a lengthy examination.
"That indicates that you stop," she said.
The engineer never hit the brakes, she added. Metrolink's chief spokeswoman, Denise Tyrrell, resigned Monday after she was intensely criticized by superiors who said she had spoken prematurely in attributing the crash to the Metrolink engineer's mistake.
In an interview Tuesday, the Metrolink conductor told investigators he did not talk to the engineer during the last two signals, an apparent breach of protocol. Safety board investigators conducted a reenactment of the accident and a "sight distance survey" on Tuesday to determine at what point the two train engineers might have seen each other.
In the test, two trains drove up to each other on the repaired track, then slowly reversed course until the two test engineers could no longer see each other. Investigators then measured the distance between the two engines.
That test showed that the engineer on the Union Pacific freight had only four seconds to react after he saw the oncoming Metrolink train. The engineer hit the brakes two seconds before the "point of collision," Higgins said.
"By then," she added, "it was too late."
Times staff writers Gale Holland and Steve Hymon contributed to this report.