> you can see the front jack release triggers the green light in the video! Actually, the amazing thing is that it's manually activated. The video explains th

> you can see the front jack release triggers the green light in the video! Actually, the amazing thing is that it's manually activated. The video explains that there is one person in charge of making sure that everyone has finished and there were no problems, which then activates the green light. In addition, there's a second person watching the lane, to check that no cars are incoming. This one even overrides the first switch if necessary.