This mobile transloading unit is designed for fast, safe custody transfer of a wide variety of liquids. It features a four-wheeled towable trailer that is easy to operate, one side of which can be used for truck transloading and the other for railcar transloading. Both sides share common transfer equipment, including hoses, filters, strainers, air eliminators, valves, sensors, overfill-protection equipment, pumps, meters and an emergency shut-off switch. Optional safety features include access platforms, gangways, and fall-protection safety cages.