Here is a video of me doing five of the attractions at Typhoon Lagoon, one of which is Storm Slides.
In the video you can see the red/green light system, the attendant at the top of the slide, the pool at the bottom as well as the audio announcements made about how to proceed.
You can also gauge the speed of the slides.
Hope this sheds some insight.
http://vimeo.com/22100919
cool video.