...or, This isn't the only thing wrong with the freeways running through downtown San Antonio.
For one, they put only a one-lane ramp for motorists coming onto I-35 North from I-10 West into downtown as I-35 North and I-10 West merge. Not only that, but they also built that lane in a manner in which all the traffic being shunted onto I-35 from I-10 has to yield the right of way to the folks in the right lane on the upper level of I-35, where the I-10 ramp goes. I suppose I-10 on the east side might not have as much traffic as I-10 on the west side, but I still think that design's dangerous because there are going to be times when the traffic from I-10 has to come to a dead stop to yield to the I-35 traffic. (I know this because I have seen it happen with my own two eyes and therefore had to do it myself.) It's not so bad coming from the other direction (where I-10 eastbound and I-35 southbound split), as the ramp from I-35 South to I-10 East goes into its own lane for a short distance -- but, again, there's one lane going from I-35 South to I-10 East on that south-side split, and two from I-35 South to Highway 90 West. And because of that, more than once I have had to take Highway 90 West instead of I-10 East because I couldn't get into that ONE LANE I needed to get into.
I know all that would be a pain in the ass to fix -- a fat lot more so than the lower level drainage problems -- but I don't understand why they built it like that in the first place. Like I tell my wife all the time going through there (and certain other places, such as the I-10/Loop 410 interchange on the east side), "The engineers who designed this need to go the hell back to school."