Shake Shake Bridge is a bridge that runs over The Logging Pond on Misty Island. Its name comes from the fact that, when an engine crosses it, it shakes violently.
In real life, the bridge would not be able to hold up the weight of an engine.
The bridge's structure resembles the bridge inside Morgan's Mine.
The bridge as depicted in the series and specials is a severe deviation by the animation team from Sharon Miller's idea; she conceived of the Shake Shake Bridge not as a half-collapsed trestle but as a suspension bridge that felt and sounded to be in worse shape than it actually was.