redundancy by slowing or stopping a train that's not being operated in accordance with signals, speed limits or other operating rules. ptc is proven technology that can prevent train-to-train collisions, overspeed derailments, and incursions into work zones. since this is a derailment involving a high-speed train, it's possible ptc could have prevented it. while this is our last on-scene media briefing, our work on this investigation is far from complete. investigators will continue interviewing the crew and employees of metro north and will interview passengers on the train and additional first responders as necessary. they will also complete some testing of the signal system and documentation and inspection of the rail cars and the locomotives. i'd like to express my sincere appreciation to all the responders and officials from state and local new york