Surround the bridge with events like this:
Code:
[o][o][o]
[u]=========[u]
[o][o][o] |
The bridge itself would also consist of an event (or a string of events, depending on its length). O events would set the bridge to be above you, while U events would set it to go underneath you.
--------------------------
Bridge Event - 2 pages
Page 1: Preconditions (none)
Event layer: "Below Hero"
Page 2: Preconditions (Switch 0099:BridgeAboveYou is ON)
Event layer: "Above You"
O event - 1 page
Trigger Condition: On Hero Touch
<>Switch Operation: {0099:BridgeAboveYou} ON
<>
U event - 1 page
Trigger Condition: On Hero Touch
<>Switch Operation: {0099:BridgeAboveYou} OFF
<>
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As you can obviously guess, this just switches the bridge to be above or below you, which is the effect you want.