A group of people walking on the side of a railroad track.
People are near a train.
A train isn't always near at a railroad track.  The train could be far away.  Or the railroad track could no longer be used by a train.
exists e1 x1 x2 x3 x4 x5 x6.(n_side(x4) & a_topic(x1) & of(x1,x2) & on(e1,x4) & of(x4,x5) & n_track(x5) & of(x5,x6) & n_railroad(x6) & Actor(e1,x3) & v_walk(e1) & (x2 = x3) & n_people(x2) & n_group(x1))
exists p1 x1.(exists x2.(near(x1,x2) & n_train(x2)) & n_people(x1))