Stage Lines, as a matter of policy, did most of their travel by daylight.  There were exceptions, especially when the shorter days approached and what was usually daylight was fast growing darker.  They had running lights on each side of the coach but they were not headlights as we know today.  This stage is trying it's best to make time so they can arrive on the flatlands before darkness overtakes them.  These mountain passes saved time but you didn't want to drive a stage with six in hand in the dark.  I think they make it.