Improvements pertaining to the realty made subsequent to the date of service of summons shall not be taken into account in determining compensation unless one of the following is established:
(a) The improvement is one required to be made by a public utility to its utility system.
(b) The improvement is one made with the written consent of the plaintiff.
(c) The improvement is one authorized to be made by a court order issued after a noticed hearing and upon a finding by the court that the hardship to the defendant of not permitting the improvement outweighs the hardship to the plaintiff of permitting the improvement. The court may, at the time it makes an order under this subdivision authorizing the improvement to be made, limit the extent to which the improvement shall be taken into account in determining compensation.