Avoiding waste is why the court takes this position:
The county decided not to build the road of which the bridge was to be a part, and did not build it. The bridge, built in the midst of the forest, is of no value to the county because of this change of circumstances. When, therefore, the county gave notice to the plaintiff that it would not proceed with the project, plaintiff should have desisted from further work. It had no right thus to pile up damages by proceeding with the erection of a useless bridge.
See the LSS tutorial Remedies 2 for the details of how the approach works.
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