any 'alternate route' would add hours to the crossing.
Last time it was shut down you had to just exit there, go down the ramp, and right up the on-ramp to bypass the bridge. Delays were minimal. A lot of traffic flows thru there of course, but it's not like a gridlock situation, you are pretty much out in the boonies. Mostly slowed down for the semis coming to a stop and then getting back up to speed.
I commuted from Asheville to E.TN (jefferson city) for a year via 40. That was miserable (but a beautiful drive on the days I wasnt thru before the sun came up).