National Transportation Safety Board officials said the death toll from Friday's collision between a Metrolink commuter train and a freight train north of Los Angeles was 26 with the death Monday of one of the 40 severely injured passengers.
Investigators said it appeared the Metrolink engineer ran through a stop signal prior to the collision, USA Today reported.
The disaster has prompted calls for requiring railroads to install new technology designed to automatically slow trains that miss stop signals, advocates told the newspaper.
"The unwillingness of rail companies to make the needed investments in safety have prevented this technology from being fully implemented," said U.S. Rep. Jim Oberstar, D-Minn., chairman of the House of Representatives Transportation and Infrastructure Committee, adding that he supports legislation that would require train-control systems.
NTSB officials told USA Today that U.S. Sens. Barbara Boxer and Dianne Feinstein, both D-Calif., promised to finalize legislation requiring the installation of "positive train control" systems. Railroads say the technology is too costly and unproven in its effectiveness.
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