In one of the stages of Tony Hawk's Underground (it is the stadium) you can see the entrance to a road but the game won't let you go there. With this glitch, you can!
How to do itEdit
Go to the area that leads you to part C. On your left there is a bar. Grab the bar, and move as far left as you can. Climb on top of the bar and jump into the audience. Surprisingly, the game doesn't notice that you are there! Go to the stairs and go on the ramps to your left. As you are doing this, watch the stairs near the top. They should be straight bars. Keep moving until you find a staircase with bars sticking out of it. Move left one more time and jump into these stairs. You will fall into the exit and you will be able to enter Glitch Road!
All the cars will be 2-D and there is an invisible wall. If you get off your board and start jumping toward the wall, you will go through it.
Why it worksEdit
When you jump through the stairs you will end up BEHIND the reseting part and you can continue on to Glitch Road.