A truss structure is suitable for supporting lighting fixtures or other loads both in use and in transport. The truss has at least four elongated chords defining between said chords a first volume generally rectangular in cross-section. In transport, the truss is supported substantially above a surface by castered carriages bearing upon that surface, the carriages connected to said truss and in a first position producing an additional volume between said first volume and said surface. The carriages are attached to the truss so as to permit their rotation between said first position and at least a second position suitable for use while remaining connected to said truss.