The human error detailed in last week's hearings on the 2008 Metrolink commuter train disaster that killed 25 people has stirred debate over what the rail industry can do to ensure passenger safety for at least six more years until technology is installed that could prevent another collision.

The tragedy occurred when a Metrolink train ran a red traffic signal and collided head-on with a Union Pacific freight train on a single shared track in the San Fernando Valley.

Federal investigators have found a rash of rule violations involving the crews of both trains: The Metrolink engineer was text messaging 22 seconds before the collision and was planning to let a teenage train buff drive the train that evening. Also, the conductor of the freight train was texting while he was on duty and tested positive for marijuana.

After the Sept. 12 disaster in suburban Chatsworth, officials stepped up efforts to improve safety measures. Federal regulators banned cell phone use by train operators and Congress passed a new law requiring technology to stop trains on a collision course. The law requires the installation of a computerized "positive train control" system by 2015.

While making plans to deploy the costly and sophisticated technology, Metrolink has added a second person in the locomotive cab and plans to install security cameras focused on train operators. However, the union representing the nation's train engineers opposes putting cameras in the trains, and some safety experts question its efficacy.