Decreasing Emergency Railroad Accident Instances Locally Act or the DERAIL Act This bill requires the Department of Transportation (DOT) to expand the statutory definition of a high-hazard flammable train (HHFT), thereby subjecting more trains to additional safety requirements. Specifically, DOT must expand the definition of HHFT to mean a train transporting one or more loaded tank cars of a Class 3 flammable liquid (e.g., benzene residue) or a Class 2 flammable gas (e.g., vinyl chloride) and other materials DOT determines necessary for safety. Current regulations define HHFT as a train transporting 20 or more loaded tank cars of a Class 3 flammable liquid in a continuous block or 35 or more loaded tank cars of a Class 3 flammable liquid dispersed throughout the train. The bill also requires railway carriers to report a train derailment that involves a train carrying material toxic by inhalation within 24 hours of the derailment to the National Response Center, state and local officials, and tribal governments.