Rush hour for Mauna Kea is just before sunset. This is when the day crews are coming down, while the summit tours and telescope operators are heading up.
The timing of this rush can be variable depending on time of year and what time sunset occurs. Twice a year this rush is at its worst, when everyone heads up and down at the same time. This can lead to some difficult driving conditions… A lot of vehicles on a road that can be challenging. A cloud of fine cinder dust and a setting Sun just adding to the confusion…
