In the next few weeks, new federal regulations will outline what the systems must do, experts said, but technical and financial challenges remain.
Some officials lament that it took one of the state's deadliest train wrecks to get things moving.
"There's no question that this tragedy made it easier," said Sen. Barbara Boxer, D-Calif. "It's a terrible thing."
The deadly Sept. 12, 2008, crash in Chatsworth -- that also injured 135 people -- left rail riders shaken. Days of television footage showed firefighters combing through the massive wreck area. Many riders on the train that fateful day had to be pulled from twisted railcars that were tossed from the tracks by the impact.
Officials pledged quick action to remedy problems and assure riders that the trains were safe. Investigators immediately focused on the possibility the train's engineer had failed to heed warnings telling him to stop. The National Transportation Safety Board confirmed that engineer Robert Sanchez received a text message 22 seconds before the crash.
Rail experts have said positive train control could have prevented the collision by alerting Sanchez or stopping the train if Sanchez did not.
"This tragedy revealed a basic flaw in rail safety in America: that there are thousands of miles of track in this country shared by passenger and freight trains headed in the opposite direction with nothing more than an engineer and signal lights to avert disaster," said Sen. Dianne Feinstein.
Feinstein, D-Calif., and Boxer were instrumental in passing the Rail Safety Improvement Act, mandating positive train control on all U.S. railroad tracks shared by passenger and freight trains by 2015. Both senators sought a 2012 deadline, which Southern California rail officials pledged to meet in October.
It will cost Metrolink $201.6 million to install positive train control on county and company-owned tracks in the Metrolink service area and on its locomotives, the company estimated. So far, officials have $74.6 million set aside.
Metrolink spokesman Francisco Oaxaca said the agency has enough money to start designing a control system to handle the passenger trains and tracks.
Officials are hopeful the remaining $127 million will come, either through federal channels explored by Metrolink, or counties in Southern California raising it their own way. Riverside, San Bernardino, Los Angeles, Orange and Ventura counties are all members of Metrolink.
Los Angeles County pledged $40 million, from a combination of state and local sources.