The Kim family was intending to follow USFS Road 23 (aka "Bear Camp Road"), a single-lane, paved, windy, twisty, scenic road that more-or-less links (in good weather) the rural area near Interstate 5 to the Oregon coast.
That they even intended to follow that road to the coast was a mistake. This road is not maintained in the winter months and is prone to snowstorms, mudslides, and rock slides. There is no gate stopping anyone from traveling this road. Sure, you could try to attempt it in the winter, but it would be sheer insanity.
Making matters even worse, they turned off this paved road onto an unpaved, dead-end, spur road. They were able to turn off onto this road because the gate in question had been unlocked and left open by vandals.
Eventually, down this spur road, is where they got stranded and the tragedy unfolded.
To even get to that point the Kim family had to pass not one, not two, but about four or five bright yellow warning signs that unequivocally stated the road they wanted to travel on was closed by snowfall/weather conditions. In addition, maps list the road they were trying to use as "Closed in Winter".