CharController on a rising bridge

I am currently creating a game using a Character Controller. I have already built my code using the FPSWalker script and is able to move my player around using controller.Move with gravity.

I have added a bridge which moves up and down in an interval of seconds. I am having no problem running fast on top of the bridge while it rises. The problem is when my player is standing idle on top of the bridge and the bridge is going up, my player sinks through the bridge collider. It seems as if the character controller collider loses contact with the bridge collider. What can I do to address this problem?