If the commission determines that the political subdivision, in case of a petition of the first class, has failed to commence the action in a court of competent jurisdiction within 60 days after the commission has made and filed its finding of just compensation, or that the political subdivision, in case of a petition of the second class, has failed to proceed diligently to submit the proposition to its voters or has failed, after its voters have voted in favor of the acquisition of the lands, property or rights, to file such action in a court of competent jurisdiction within 60 days thereafter, the commission shall make and file its order declaring that such finding shall no longer be of any force or effect, and make its finding as to the reasonable expenditures necessarily incurred by the owner in the proceeding before the commission, which should be assessed against the political subdivision. The political subdivision shall thereupon be liable to the owner in the amount thus found by the commission, and the owner may thereupon maintain an action against the political subdivision for such amount in any court of competent jurisdiction.