I got a lesson in this last night. The limo driver I had passed the on-ramp to Hwy 16 by a long shot. We were at about Fort Lewis when he thought to ask me. We then turned around to go back to Hwy 16, but the on-ramp was closed. I told him "this would normally be the right exit," and he decided to go through the barricades anyway. A surly State Trooper parked there gave the driver a ticket. We then had to find a way to get on Hwy 16. Fortunately, I knew the way, but the detour took some time.
Once we got on Hwy 16 an hour later than we should have, it was fairly smooth sailing. That extra hour of time meant I got home at 3am instea d of 2am.
Most of this would have been avoided had I paid attention and took a more active role in the process.