A large crowd waiting at a train crossing.
The people are waiting for the train to pass.
Just because the crowd are waiting at a train crossing doesn't mean they are waiting for a train to pass. They could be waiting for another event.
exists e1 e2 s1 x1 x2 x3 x4.(a_topic(x1) & at(e1,x3) & Actor(e2,x4) & v_cross(e2) & (x3 = x4) & n_train(x3) & Actor(e1,x2) & v_wait(e1) & (x1 = x2) & n_crowd(x1) & a_large(s1) & Theme(s1,x1))
exists e1 p1 x1 x2.(n_train(x2) & n_people(x1) & Topic(e1,p1) & Actor(e1,x1) & v_wait(e1) & exists e2.(Actor(e2,x2) & v_pass(e2)))