On I-25 southbound, just before Steele Street, there are a set of skidmarks that literally run from the left lane to the right wall. I see things like that, and my mind starts to work- I try to figure how empty the highway had to be to leave uninterrupted skidmarks across that many lanes of traffic. I try to figure how fast the car had to be going. And I wonder if anyone was hurt, hoping not.
The world is full of tracks of things that have gone before- rabbits on a snowy street- dogs in mud- cats across your car roof. If you stop to examine them, imagine what happened, sometimes it's pretty interesting. Down on Champa street between 16th and 15th in denver, there are gouges running across the street, up onto the sidewalk, and all the way to the doors of a building. it looks to me like the Light Rail train derailed, but I have not been able to find any definite confirmation
For Further reading on tracking- The Tracker by Tom Brown Jr.
and Tom Brown Jr.s page at wikipedia