People riding escalators.
People are being transported on an escalator.
Riding and transported as synonyms.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_escalator(x3) & (x1 = x2) & n_people(x1))
exists e1 x1 x2.(on(e1,x2) & n_escalator(x2) & Theme(e1,x1) & v_transport(e1) & n_people(x1))