l l
______l l_____
l ____****____
l l l l
l l l l

* is the bridge

When you come from the bottom or top the bridge appears overhead,you can go in any direction but not the far left or right(It's too high. When you come from the left or right the bridge is below you and you can not go up or down.

The problem is apparent. The bridge is always below you and can go in any direction.

I have an idea that involves lots of events but I just can't seem to change the direction passabilty.