CHICAGO -- For young fans of trains, getting an up-close look at the massive machinery can be a dream fulfilled. For train workers, indulging the children' fantasies can be an ego boost.
To rail officials, it's distressing, forbidden and potentially deadly.
A series of recent incidents suggests some engineers are crossing the line and putting passengers at risk by giving fawning young admirers too much access to trains.
An engineer in Chicago was recently suspended after reports that he let a teen operate a commuter train, a ride the 18-year-old boasted about on his MySpace page. And a crash between a freight train and a commuter train that killed 25 people last month in Los Angeles allegedly occurred seconds after the commuter-train engineer sent a text message to some young train buffs.
These and other incidents have unnerved passengers and railway officials alike, and they've raised questions about whether oversight and safety rules are adequate.
Passengers entering locomotive cabs and driving trains "is not an epidemic," said Matthew Melzer, a spokesman for the National Association of Railroad Passengers. "But what it brings into focus is that there are human safety factors."
The crux of the issue is concentration -- ensuring engineers keep their attention on the controls and on the tracks ahead.
As commuter trains barrel along increasingly congested tracks, some sharing lines with freight trains, an accident is at least a possibility at any second, said Judy Pardonnet, a spokeswoman for Chicago's Metra. Among the potential hazards are car drivers who foolishly try to slip around crossing gates.
"Operating a train is lot more complicated than it appears to the average person, who might think, 'It's just a train that goes straight down a track,'" Pardonnet said. "But it is very complicated and it needs an engineer's full attention."
There are rules are designed to help make sure engineers aren't distracted.
They are strictly barred, for instance, from letting passengers into a locomotive cab, and they can't use potentially distracting items such as cell phones, BlackBerries, newspapers and books, Pardonnet said.
Neither Pardonnet nor other Federal Railroad Administration could provide details about the teen's alleged operation of a Metra train, including when and on what line it supposedly occurred. Pardonnet said his MySpace page has been taken down.
The engineer allegedly involved has been suspended pending an investigation, as have two others accused of letting the same teen into their cabs on other routes, Pardonnet said.
"If these allegations are true, there will be very quick proactive actions," possibly including dismissal, she said. An investigative hearing is scheduled for early next month.
"If these alleged actions occurred it is completely unacceptable," said Federal Railroad Administration spokesman Steve Kulm. "No one should be operating a train who is not certified to do so."
A similar incident occurred in Boston earlier this month when a trolley driver was fired after he was caught by a passenger on camera with his young son and nephew with him behind the wheel -- though there was no indication the children operated the trolley. The incident came to the attention of authorities after the photos were posted online.
Among younger Americans, social networking Web sites like MySpace and video sharing sites like YouTube have become the forum of choice for rail aficionados to boast about trains they've seen or ridden, said Wayne Eissele, of the Strasburg Rail Road Company, which provides rides on steam trains to tourists in Lancaster County, Pa.
Eissele has had brushes with die-hard train aficionados -- sometimes called "foamers" because "they foam at the mouth while they're looking at their favorite trains," Eissele said.
Engineers letting children, friends or "railfans" into a locomotive's cab was fairly common decades ago, he said. Now federal, state and train-service rules now prohibit it.
But even those who travel hundreds of miles just to watch trains can pose a hazard, Eissele said.
"Some guys go around with cameras in hand at railroads -- hanging out all day, getting on the tracks, making a nuisances of themselves by annoying employees," he said. "Generally it's not a problem -- but there's always a fringe element."
Among the steps the Federal Railroad Administration took following the Sept. 12 collision in Los Angeles was to issue an emergency order explicitly prohibiting the use of personal electronic devices by railroad employees while operating trains. The commuter-train engineer was among those killed.
Last week, President Bush signed a sweeping railroad safety bill mandating other measures supporters say could have prevented the deadly crash. The legislation had stalled, but lawmakers quickly reached a compromise after the Los Angeles crash.
The law will require more rest for workers and technology that can stop a train to avoid a collision.