Instructions
Perform a search of your hard drive for the following file location and open it:
C:\Documents and Settings\[your Windows username]\Application Data\Atari\RCT3\Options.txt
Add the following lines to the options.txt page you just opened: AttractionSceneryAllowTerrainIntersect 1
AttractionSceneryAllowSceneryIntersect 1
TrackAllowSameTrackIntersect 1
These lines of text need to be on separate lines and need to be typed exactly as they appear.
Open the game normally and either start a new park or open an existing park. Collision detected should now be turned off and the cars on your rollercoasters should fly off the tracks. If the cheat is not working, double check the text, as it is very easy to make a mistake.