Bümer-45/60; Trans-Dimensional Alloy:

The steel that the bridge is made of isn’t just metal, it is a crystalline structure that has a fourth coordinate. That fourth coordinate in its structure makes this alloy non-Euclidian.

The metal reaches forward and backward through time, transferring energy across a range rather than a point. It defers the problem into the future, sometimes the past, but mostly it is lost in hyperdimensional gaps.  This makes it unbreakable under normal circumstances.