If you haven't seen this thread, you might want to consider it. Mianne Lift Bridge Lower Limit Switch Enhancement
I found while you can "usually" get the switches adjusted, the Mianne method of using standard momentary toggles with an angle bracket lends itself to easily getting "out of whack" and you have a real problem on the downward travel if the switch doesn't trip before the lift gate hits the stops. This makes the downward stop about as bulletproof as I can imagine using simple switches.
