Complex sentence: González Bastías is a small town which marks the halfway point at 44 km, and an obligatory stop for the trains in both directions, as there is only one track, and this is where they pass each other.
Split into simpler sentences: González Bastías is a small town which, at 44 km, is the line's halfway point. It is an obligatory stop for trains in both directions, since there is only one track and they must pass each other.