Positive Train Control System

As federal investigators focus on the likelihood of human error being the cause of the Dec. 1 derailment that killed four passengers, attention has been placed on the federal requirement for all railroads to install positive train control systems.
Dec 5, 2013   The Wall Street Journal - New York
A cutting-edge railroad collision avoidance system is being installed in Los Angeles. Dan Weikel and Richard Simon examine the system, and the reasons why the federal government is backing down from requirements to install the system nationwide.
Feb 14, 2012   Los Angeles Times