Note: Matthew L. Wald of The New York Times co-wrote this article.
A day after federal investigators said an engineer in last week's deadly train collision outside Los Angeles had been text-messaging on the job, California's railroad regulators temporarily banned the use of all cellular devices by anyone at the controls of a moving train.
The emergency order was passed unanimously on Thursday by the five-person California Public Utilities Commission, which noted the lack of federal or state rules regarding the use of such devices by on-duty train personnel.
Michael Peevey, the president of the commission, which oversees rail traffic in the state, said in a statement that the prohibition on cellular use was "necessary and reasonable."
The commission's order came after an announcement on Wednesday from the National Transportation Safety Board that investigators had determined from phone records that the engineer, Robert Sanchez, sent and received text messages while at the controls of the Metrolink commuter train that collided head-on with a Union Pacific freight train on September 12.
Sanchez's train, carrying about 225 passengers, ran a red light northwest of downtown Los Angeles. Twenty-five people were killed and more than 130 injured in the worst domestic train accident since 1993. Sanchez, who did not brake before the collision, was killed in the crash.
The timing of the messages Sanchez sent and received was still being determined, according to investigators for the National Transportation Safety Board, who stopped short of saying that the distraction of text-messaging might have been a cause.
"We're trying to coordinate the times," a board spokesman, Peter Knudson, said Thursday.
The board has been looking into reports that Sanchez was text-messaging with a teenage train aficionado at the time of the accident.
Knudson said the teen-ager had said that he received a message at 4:22 p.m. But, Knudson cautioned, "We don't know if his 4:22 is the same as the train's 4:22," he said.
Investigators at the board commonly face this problem. In plane crashes, for example, they must correlate the time-stamped events on a flight data recorder or a cockpit voice recorder with the clock on a radar record or the time as recorded in tapes of air-to-ground communications.
The synchronizing of cell phone data is less common. And, as with cell phones, there is sometimes a lag of several minutes in the sending of text messages, investigators noted.
The board member who was sent to the scene, Kathryn Higgins, said that the object of investigators was to create a timeline of the accident, using data from various sources, including the time marked on the event data recorders of the trains.
Higgins noted that Sanchez had sent and received many text messages over the course of his shift, and that the railroad already bans texting while the operator is running the train. But Sanchez's shift included long periods when he was not operating the train, Higgins said. "During off time, down time, personal time, it's not prohibited then," she said.
Likewise, the commission's decision applies to train personnel working with locomotion, including engineers, brakemen and conductors, but does not cover times when the train is not moving or when use is approved by management.
The panel also said it would consider making the emergency order permanent.
Writing, sending or reading text messages while driving a car could soon be illegal in California, whose legislature recently passed a bill banning such behavior though it has not yet been signed into law by Gov. Arnold Schwarzenegger, a Republican.