American Association of State Highway & Transportation Officials (AASHTO)
Crossing Inventory & Accident reports Federal Railroad Administration, Office of Safety Analysis
Federal Railroad Administration (FRA)
Manual on Uniform Traffic Control Devices
Railroad Crossing Safety & Trespass Prevention, Federal Railroad Administration
Surface Transportation Board (STB)
USDOT Guidance on Traffic Control Devices at Highway-Rail Grade Crossings
USDOT Railroad-Highway Grade Crossing Handbook
US EPA on locomotive emissions