I've lived in Austin for 20 years, and have encountered snow there exactly three times (if you want to call that snow). It freezes over about once every two years.
Due to infrequency, Austin drivers can't deal with it: there's always a ridiculous number of accidents with even the slightest bit of ice on the road. Even worse, the city doesn't know what to do about it either. They always pour sand on the road, but sand doesn't do anything to make it less slippery, salt on the road is what helps that, as I understand.
This sand actually makes it slippery even after the ice and snow are gone, which is ironic because everyone wants to drive fast again now that the ice has disappeared.
A lovely creation by University of Texas graduate Ed Bluestein, the split deck portion of I35 running next to the University of Texas was rated one of the 10 most dangerous sections of road in America. I'm not so sure that it's urban legend, but I have also heard that Ed committed suicide due to the tragic number of deaths.
It is difficult to detail the public menace that is I35, but, in general, the problems are three-fold.
- blind entrance ramps - The lower deck is lower than the feeder roads, causing difficulty in alignment. No prep time, you just have to go for it and hope for some friendly drivers.
- short entrance ramps - One has about 30 meters (100 feet) to merge. This is accentuated by several problems: 1) the aforementioned blindness, 2) the entrance ramp ends in a concrete wall. The shoulder technicall exists, but is only 1 car width wide, give or take a foot. 3) You're expected to merge from the 40 mph feeder to 60 mph on the freeway in that time.
- reversed exit lanes - As /dev/joe mentioned, the right two lanes go to the upper deck; the left two are your exits for midtown. While it's well labeled, people frequently make a last second sweep back across the median to switch back to lower deck lanes. I've seen them flip back and forth several times in indecision.
The first two combine with panicky drivers to cause people to STOP at the end of the accelleration lane because they are terrified. Then you have a bunch of cars lined up who all have to wait for gaps in traffic. Also, they now have to accellerate from 0 to 60 to get in. Number three often has people stopped on the median in the middle of traffic as well. In driving on the lower deck, you have to deal with people who are dealing with these problems, so it's sometimes not pleasant on either side.
Now for the tips to survive I-35.
- The yuppies don't want to scratch their SUV's, so they're pretty generous about letting you in. You can't see them from the access ramp, but they can see you, and will get out of the way.
- There is the upper deck. If you aren't an aggressive driver, use it. I personally prefer the thrill of the lower deck, because most of the Sunday driver types will stick to the upper deck out of fear for their lives.
- Skip it. It's often convenient to take Highway 183 over to Mopac and and go south from there. No I35 Split Deck Death Trap over there, although we used to have an artificial rain system.
- Wait. The city is actually in the process of repairing I-35, extending the entrance ramps all the way to the exit ramps by pushing the concrete walls back a few feet. I'll be sad to see this fine stretch of badlands dissapear, but The City of Austin appreciates it.