At this point, we had no idea why there was a detour… As you can see, straight ahead, is the "real" road, but it's been shut down…
So, I jumped out and shot a few photos of the bridge and the area, for posterity.
We were the first car in the queue, and waited about 12 minutes or so, when suddenly this very long line of cars began coming over the bridge!
After about 3 minutes the cars stopped flowing, and another minute or two the light changed to green, and we proceeded, cautiously, over the bridge. About 1/4 mile up the road we saw why there was a detour!