58 is only closed for a few hundred yards at Sand Canyon Road. I went through it a couple of months ago. The freeway bridge is being rebuilt so what they do is take the traffic off the freeway on the off ramp and then you drive right back up the on ramp past the bridge. They have closed Sand Canyon Road so there is no cross traffic. There was no back up at all when I went through it. I didn't even remember it until I saw this post. The Caltrans website is a little weird the way they have this worded.