The antonym of the phrase "crossing bridge" would be staying put or staying on one side of the bridge. It could also mean avoiding the bridge entirely and taking a detour to reach the other side. In some cases, the antonym could be crossing the bridge multiple times, back and forth, rather than just crossing it once. Additionally, if the bridge signifies a transition or passage from one state to another, the antonym could refer to avoiding any changes and staying in the same state. Ultimately, the antonym of "crossing bridge" would depend on the context in which it is used.