wow what a c unty thing to say and as far as what your asking anywhere in austin for the most part is safe. but if you stay on the downtown side of I35 you should be fine. on weekend nights around that time there should be numerous people everywhere and everywhere is also well lit. have fun
If you do make it to sixth come in to Pete's Piano bar and I'll buy you some drinks. I'm one of the piano players so I'm pretty easy to find.