People gathered to look at trains.
People are boarding the train.
Looking at a train is different than boarding it.
exists e1 p1 x1.(Topic(e1,p1) & Actor(e1,x1) & v_gather(e1) & exists e2 x2.(at(e2,x2) & n_train(x2) & Actor(e2,x1) & v_look(e2)) & n_people(x1))
exists e1 x1 x2.(n_train(x2) & Theme(e1,x2) & Actor(e1,x1) & v_board(e1) & n_people(x1))