But after the Maryland system's accident in 1996 and another fatal accident a week earlier in New Jersey, the Federal Railroad Administration issued an emergency safety order to review some aspects of push operations and the safety of putting passengers in lead cars.
"Occupants of cab cars may incur a significantly higher risk of serious injury when compared with occupants of a locomotive-hauled [train], if the cab car collides with a heavier rail vehicle or any highway or rail vehicle transporting hazardous materials," the Federal Railroad Administration concluded in its safety order.
The agency never restricted the practice of operating trains in push mode, and today each commuter line is allowed to determine many of its own practices, speed limits and safety measures.
In 1999, the Federal Railroad Administration did issue tougher crash standards for cab cars, requiring, for example, structural posts on the outside corners of cab cars that are designed to withstand hitting a 41,000-pound rigid object at up to 15 mph. Earlier standards had required that cab cars withstand crashes up to 11 mph.
But the rules apply only to cars built after 2002. Cars not up to standard but already in use were grandfathered in. Because passenger coaches last 30 years or more, it will be decades before the 1999 improvements are fully implemented.
The Metrolink cars in the Glendale crash were built before 1999 and do not meet the tougher standards, said agency spokeswoman Denise Tyrrell. But even if they met all of the 1999 rules, it is not clear how many deaths and injuries could have been prevented.
And despite the Federal Railroad Administration's 1996 safety order, no one ever conducted a comprehensive examination of push-pull operations, says the American Public Transportation Assn., a trade group representing the public transit industry, including commuter rail systems.
"There is no central data repository that says this accident was a pushing operation and that accident was a pulling operation," said Greg Hull, the group's director for operations, safety and security. "We know it anecdotally."
After the Glendale accident, Metrolink and the Federal Railroad Administration have said that they continue to believe in the safety of cab cars. "There is no evidence to indicate that pull operations are necessarily safer than push operations," the Federal Railroad Administration said in a statement to The Times.
