The policy of only replacing a main when a sufficient number of breaks occur is mentioned in case law. See, e.g., Roberts Realty Corp. v. City of Great Falls, 500 P.2d 956, 959 (Mont. 1972); Grace Co. v. City of Los Angeles, 168 F. Supp. 344, 349 (S.D.Cal. 1958), aff'd 278 F.2d 771, 773 (9th Cir. 1960). In Roberts, the city's replacement formula called for installation of new pipe when "the annual cost of repairing the breaks becomes greater than the annual cost of replacing the main."
There is a split of authority as to whether breaks in buried water mains occur in the absence of negligence. See, e. g., City of Houston v. Church, 554 S.W.2d 242 (Tex.Civ.App.1977), and Roberts Realty Corp. v. City of Great Falls, 160 Mont. 144, 500 P.2d 956 (1972), discussed below. Here the trial court had to defer to expert opinion as the answer to this question is not a matter of common knowledge.
However, many jurisdictions refuse to apply res ipsa loquitur to water main breaks. E.g., Jennings Buick, Inc. v. City of Cincinnati, 63 Ohio St.2d 167, 406 N.E.2d 1385, 1390 (1980); City of Houston v. Church, 554 S.W.2d 242, 243-44 (Tex.App. 1977); Roberts Realty Corp. v. City of Great Falls, 160 Mont. 144, 500 P.2d 956, 963 (1972). As the court in City of Houston correctly observed, where there is evidence that in the locality a particular type of accident frequently occurs as the result of unpredictable natural forces, res ipsa loquitur should not apply; it cannot then be said that the accident "does not ordinarily occur in the absence of someone's negligence."
"Where it is impossible to say upon what theory or under what part of the court's instructions a verdict is based, error in any one of the instructions which is prejudicial and which may influence the jury entitles the unsuccessful party to a new trial." Roberts Realty Corp. v. City of Great Falls (1972), 160 Mont. 144, 159, 500 P.2d 956, 964. I would therefore reverse the District Court and send the matter back for new trial.
The contention that an instruction does not state the law cannot be considered absent a proper objection at trial. Roberts Realty Corp. v. City of Great Falls (1972), 160 Mont. 144, 500 P.2d 956. The third assignment of error asserted is the District Court's failure to admit a petition of the Rosebud County Commissioners and other documents concerning the warning devices at the Koselka crossing.
We have previously held that a party has the duty of raising his objection to the instruction at the time of trial or the opportunity is lost. Roberts Realty Corp. v. City of Great Falls (1972), 160 Mont. 144, 154, 500 P.2d 956, 962. Objections to instructions not raised in the trial court cannot be raised for the first time on appeal.