Friday's disastrous collision that took the lives of at least 25 people might have been prevented if Metrolink and the region's freight railroads had installed sophisticated warning and control devices, according to safety experts who have been calling for such improvements for decades.
The National Transportation Safety Board, which investigates crashes and recommends ways to avoid them, began calling for the technology 30 years ago, after a train wreck in Louisiana. The safety board has repeatedly advocated the technology for high-risk corridors where freight and passenger trains operate side by side.
Southern California has more freight trains and commuter trains sharing tracks than any other place in the United States. But railroads and commuter lines here have not installed the technology, which is in use in parts of the Northeast and on routes between Chicago and Detroit.
Railroad officials have said the collision avoidance systems, known as positive train control, cost too much and are not yet reliable enough to install nationwide. That response frustrates safety experts.
"I'm not surprised that once again there has been a terrible, preventable train collision," said Barry M. Sweedler, a former senior director of the NTSB, who retired after 31 years. "It's extremely frustrating. They know what to do to solve these things."
The Federal Railroad Administration estimates that putting positive train control on 100,000 miles of track nationwide would cost more than $2.3 billion. Currently, about 4,000 miles are covered. Metrolink officials said they did not have cost estimates for installing controls on their system.
Positive train control combines digital communications with Global Positioning System technology to monitor train locations and speeds. If engineers fail to comply with signals, which Metrolink says was the case in the Chatsworth accident, the electronic devices automatically apply the brakes.
The sophisticated systems can detect speed-limit violations, improperly aligned switches, unauthorized train movements and whether trains are on the wrong track or have missed signals to slow or stop. It does not warn crews about obstacles on tracks.
The systems are "applicable any place you have freight and passenger trains occupying the same track," said William Keppen, a railroad consultant based in Annapolis, Md. "You need to look at putting them in areas with the highest risks. The Los Angeles area is exactly what we are talking about."
Francisco Oaxaca, a Metrolink spokesman, said Metrolink does not use positive train control because of the complexity of its track system, which is shared by Union Pacific Railroad and Burlington Northern Santa Fe Railway Corp. He contends that to be effective, positive train control systems would need to be installed nationwide because freight trains move across the country.
Metrolink is "on the forefront of safety enhancements," Oaxaca said, and would not hesitate to use any technology that worked across different railroad systems.
Positive train controls "don't exist in any form currently in this country other than test installations in limited locations or as pilot programs," Oaxaca said, adding that "I think every railroad operator has looked into it."
According to the Federal Railroad Administration, positive train control projects exist at nine railroads in at least 16 states, but not in California.
The railroad administration asked its safety advisory committee to address positive train control in 1997. The agency has said in the past that railroads, labor unions and the agency's own staff have agreed that the costs of the systems outweigh the safety benefits.
Railroad industry representatives said developing positive train control has taken so long because of high costs and reliability problems. Hundreds of millions have been invested in research, they said.
Edward R. Hamberger, president of the Assn. of American Railroads, the industry's trade organization, said one of the technical challenges is designing a uniform system that works across the nation's 140,000 miles of track. He also said the devices can give false readings and that railroads don't quite know how much distance should be maintained between trains.
"Technical problems remain, but we are getting them worked out," Hamberger said. "You just can't put something out there and hope it works. It has to be proven."
The NTSB said that automated warning systems were needed to compensate for human error. The safety board has investigated a long list of train accidents in which operator fatigue, sleep disorders, medications, inattentiveness or mistakes in judgment led to accidents. The board has power to investigate and make recommendations after crashes. It cannot order federal agencies to take action.