Some railroads - including Metrolink - prohibit operators from using cell phones on the job, but the commission's president, Michael R. Peevey, has said the rules are widely ignored. There is no federal regulation of cell-phone use by railroad workers and until Thursday there had been no California rules.
Richard Clark, the commission's director of consumer protection and safety, said the use of cell phones was "implicated" in two earlier accidents this year involving other rail systems, but he declined to comment on its specific role in either case until the investigations are completed.
Under the new order the board approved in San Francisco, violators could be fined up to $20,000 per violation or have their operations shut down.
"Today's action will protect the public," Peevey said. "What we're doing today is just a modest first step in a much larger effort to improve railroad safety."
The National Transportation Safety Board requested the cell phone records of engineer Robert Sanchez after two teenage train fans said they exchanged text messages with him shortly before the crash Friday in the San Fernando Valley neighborhood of Chatsworth.
An NTSB statement issued Wednesday night did not say how many messages were found in the records or if any texting occurred shortly before the crash.
Sanchez's cell phone was not found in the severely crushed and burned wreckage, but the teens told KCBS-TV last week that they received a text message from the engineer at 4:22 p.m. - a minute before the collision.
The crash occurred at a curve in the track just short of where a 500-foot-long tunnel separates Chatsworth from Simi Valley and Moorpark in Ventura County.
Less than an hour before the wreck, Sanchez had called in an order for a roast beef sandwich that he was to pick up after making the train's final scheduled stop in Moorpark, the owner of the sandwich shop said Thursday.
"He said he was at Union Station (downtown) and that he wanted to call ahead to place his order," said Randy Richardson, owner of The Hub sandwich shop. "He wanted to make sure we were going to be open when he got to Moorpark, and said he would pick it up during his layover."
Richardson said Sanchez regularly stopped by his shop in the last two years.
"He was a super nice guy. We talked about sports, the weather, politics, what's going on in the news. Just a regular Joe," Richardson said.
The NTSB has determined Sanchez did not apply the brakes before the collision and ran a red light that could have prevented it. The agency said the tracks and signals were working properly and that human error was to blame.
Investigators are looking into Sanchez's work schedule. He was working an 10½-hour split shift at the time of the crash. He began his shift at 6 a.m., took a nap during a 4½-hour break and resumed duty at 2 p.m., about 2½ hours before the crash, the NTSB said. His shift was to have ended at 9 p.m.
Memorial services were held Thursday for some of the crash victims, including Los Angeles police Officer Spree Desha. "She was all we could ever ask of someone who puts this badge on their chest," Chief William Bratton said.
One of the most compelling images in the hours after the crash came when police officers and sheriff's deputies formed lines and saluted as Desha's flag-draped body was carried from a crumpled train car.
In 2003, the NTSB recommended that the Federal Railroad Administration regulate the use of cell phones after finding that an engineer's phone use contributed to a fatal May 2002 accident in Texas.
Members of the FRA's railroad safety advisory committee have been considering restricting electronic device usage in the locomotive cab as it develops new safety rules, agency spokesman Steven Kulm said. He said the group discussed the matter in meetings earlier in the year and plans to meet next week in Chicago.
Associated Press Writer Terence Chea contributed to this story from San Francisco.