As federal investigators piece together exactly why a Metrolink commuter train blew through three signal lights before smashing into a freight train, a debate is emerging over what to do to ensure it never happens again.

In the days since the deadly crash that killed 25 people and injured 135, some public officials have embraced an immediate technical fix. Called Positive Train Control, it would provide a fail-safe system to stop a train automatically if an engineer fails to respond to signals or speed controls on the track.

Others argue that the rail system needs much more than that. They say a big infusion of money could pay for upgrading the infrastructure that has many trains running on single tracks shared by both commuter-rail passengers and freight trains.

In the age of satellite tracking devices and air traffic control, two trains running head-on into each other with disastrous consequences feels out of time, some say.

"A friend of mine said this is such a 19th century accident," said Bill Fulton, a Ventura City Council member and a member of the Ventura County Transportation Commission. "The basic issue is that for the last 85 years we've invested relatively little in rail, especially out in the West."

The Metrolink crash in Chatsworth will push new technological fixes, said Fulton, but it should also start a discussion about the rail system in Southern California. The system is carrying not just a growing number of commuters but also massive loads of freight.

"There's no question there are lots and lots of operational improvements we need to bring this system up to speed so we truly have a world-class system," he said.

While introducing legislation last week to force railroads to install Positive Train Control, Sen. Dianne Feinstein, D-Calif., asked a question many others have posed since the deadly crash.

"How can you put commuter trains on the same track as freight trains — going in opposite directions — with nothing more than a signal that can be missed, and has been missed, to avert disaster?"

Willingness to take action'

The answer to Feinstein's question goes beyond who bears responsibility for the Sept. 12 crash and requires knowing the history of commuter rail in the second-busiest passenger rail system in the country.

Back when Metrolink was being formed in the late 1980s and early 1990s, Southern California had to play catch-up with other metropolitan commuter rail services. Metrolink was cobbled together by six counties as a quick, cost-effective way to get a system up and running.

Instead of building an entirely separate heavy rail system like BART in the San Francisco Bay area or some sort of light rail system, the six counties piggybacked their system onto an existing freight line.

It would have been "orders of magnitude" more expensive to build a whole new alignment, said Mike McGinley, former director of engineering at Metrolink.

At the time, Metrolink and the various counties were able to buy portions of the rail line from the then-floundering Southern Pacific Railroad Co.

Very quickly, the agency was able to jump-start commuter services for an initial cost of about a billion dollars, but there were compromises.

The system is old, with mostly single track, and it has to be shared with freight traffic and Amtrak rail service.

It's time to look at that system and upgrade it, said Paul Dyson, president of RailPAC, which advocates for better rail service in California.

"The thing that's lacking is a willingness to take action before this kind of accident happens," said Dyson. "We have the second-busiest passenger rail system in the country, and yet we still have large sections that are single track. It's embarrassing."

It would cost from $60 million to $80 million to build double tracking along an 8-mile stretch between Van Nuys and Chatsworth — "expensive but needed," said Dyson, a Burbank resident.

"Compare that to the $100 million my city spent to build a new ramp onto the highway," said Dyson, who also serves as vice chairman of Burbank's transportation commission. "That was just to ameliorate rush hour congestion for about one hour each day so that people going to and from the studios don't have to wait, and yet they can't find the $60 to $80 million to improve safety and punctuality."

Already controls in place'

In Ventura County the line is all single-track. The line out of the county, through a tunnel near Santa Susana Pass and into Chatsworth, where the accident occurred, carries 24 passenger trains and 12 freight trains back and forth every day.

"Trains or multiple trains sharing a single track is common throughout the United States," said Ginger Gherardi, former director of the Ventura County Transportation Commission. "Positive Train Control is a good thing, but there are already controls in place — dispatching, control lights, signals and verbal signals. Of course, that all leaves room for human error."

While county officials have long looked at double-tracking, it couldn't happen without some sort of local revenue source, like a transportation sales tax, as seed money for bigger contributions from the state and federal governments.

"There's just never been the money for double-track," Gherardi said.

Voters here twice voted down such measures, and officials are looking to put a measure on the ballot in 2010 that would help raise money for local transportation like road improvements, public transportation and commuter rail.

Many other counties have local sales taxes to pay for transportation, but Ventura County does not, so the county is at a competitive disadvantage in getting matching state or federal money for big projects to improve infrastructure.

Right now the emphasis in Ventura County has been to improve the existing line with sidings, which are short sections of track parallel to the main line. A train can wait on a siding so that a train traveling in the opposite direction can pass it, said Darren Kettle, director of the VCTC.

But even sidings are expensive, Kettle said. It's costing $7.5 million just to improve an existing, 1.5-mile-long siding between Oxnard and Camarillo, he said.

County may be a stepchild

"It's admirable how far Ventura County has gotten without (a transportation sales tax), but it's going to become a sort of stepchild for a lot of improvements without one," said Bart Reed, executive director of the Transit Coalition, which advocates for public transit in the Los Angeles region. "The biggest issue is the lack of passing tracks."

But Reed and others have said neither double-tracking nor more sidings would have prevented the Chatsworth accident.

That section of the line is not likely to be double-tracked anytime soon because it is so close to the tunnel at Santa Susana Pass. A second tunnel would have to be built at significant cost.

In addition, the accident happened right next to a siding. The Metrolink train was supposed to have waited while the freight train pulled into that siding, before the Metrolink train moved forward. But the engineer failed to heed the signals.

"These kinds of accidents can happen on double-track," said McGinley.

He pointed to the 2002 accident in the Orange County city of Placentia, where a fright train ran a red light and rammed into a standing Metrolink train. That accident killed two people.

McGinley also brought up a 1987 Amtrak accident in Maryland that left 16 dead after the engineer ran through a red signal light at over 100 mph and into another train.

"The only way to prevent such accidents is with some sort of automatic train-control system," said McGinley.

"There are good prototypes; I've seen them. The problem is the FRA (Federal Railroad Authority) wants perfection."

The kind of "overlay" system required here — one that would work with multiple rail companies — depends on global position systems that have lapses in coverage because of tunnels and static.

"But they are 99.99 percent reliable," said McGinley.

When you combine that with the current signalling system, you improve the safety performance greatly. He said the system chance for failure is something like 1 in 1 million.

It's several years away'

While the technology for Positive Train Control has been tested and used on more than a dozen lines and was placed on a "most wanted list" by the National Transportation Safety Board in 1990, there is disagreement about whether it can work here.

"There's been some misinformation out there about Positive Train Control," said Keith Millhouse, a member of the Metrolink board of directors and a Moorpark City Council member.

"There isn't something that's just on the shelf ready to use for a system like ours that has multiple users on different tracks with different equipment," Millhouse said. "It's several years away, but Metrolink is taking a leadership role in ensuring that this doesn't happen again."

Millhouse's statement — as well as comments from Metrolink CEO David Solow, who said it wasn't a matter of cost that has kept the technology out of trains here, but a matter of finding a system that works — came just after the transit agency endorsed legislation to make the technology mandatory within four years.

But the backers of that legislation, which has been introduced in both the House and Senate, have argued that the technology would have prevented this accident.

The accident "may have been avoided had the proper technology been in place," said Rep. Adam Schiff, D-Pasadena.

With Rep. Henry Waxman, D-Los Angeles, and Rep. Elton Gallegly, R-Simi Valley, Schiff introduced legislation as a companion to the bill introduced in the Senate by Feinstein and Sen. Barbara Boxer to make Positive Train Control mandatory on trains in "high risk" areas like Southern California by 2012 and the rest of the nation by 2014.

Estimates peg the cost from $2 billion to $4 billion to install the technology on the roughly 40,000 locomotives running on the 140,000 miles of track across the nation.

Under the legislation, the cost would be borne by each railroad company or agency. Metrolink would spend several million dollars to outfit its 40 engines. Others in this region, including Union Pacific, Amtrak and Burlington Northern Santa Fe Railway, would face significantly higher costs because they have many more engines.

"We know that Positive or safe Train Control would prevent 40 to 60 accidents a year and even fatalities and 55 injuries a year," Feinstein said when she introduced the bill in the Senate early last week. "So why hasn't it been put in place? I actually believe it's negligence, and I'll even go so far to say that I believe it's criminal negligence not to do so."