These going before - Going before Paul and Luke. Dr. Doddridge supposes that only Tychicus and Trophimus went before the others. Perhaps the Greek most naturally demands this interpretation.
Tarried for us - The word “us,” here, shows that Luke had again joined Paul as his companion. In Acts 16:12 it appears that Luke was in Philippi, in the house of Lydia. Why he remained there, or why he did not attend Paul in his journey to Athens, Corinth, Ephesus, etc., is not known. It is evident, however, that he here joined him again.
At Troas - See the notes on Acts 16:8.