It is a huge agency that covers not only railway safety but many other categories of transportation safety.  They include aviation, highway, marine, and pipeline & hazardous materials.

The NTSB is an independent agency.  Its core objective is to determine the probable causes of a transportation accident while promoting transportation safety.  The Board is responsible for investigating and accident, performing safety studies, and evaluating government agency programs’ effectiveness on accident prevention.

The Board also writes safety recommendations based on their investigations and studies with the goal of preventing future accidents thus saving lives and reducing injuries.  These recommendations are one of NTSB’s biggest focuses.

The NTSB investigates the probable cause in all US civil accidents, selected highway accidents, railroad accidents involving passenger trains or a train accident that has fatalities or major property damage.  This list also includes major marine accidents, pipeline accidents with fatalities or property damage, releases of  hazardous materials, and transportation accidents that are recurring.

The NTSB’s website includes updates on ongoing investigations including the Metrolink train accident.