What is the test for a motion to compel production of accident investigation reports?

Even so, we feel compelled to cite the parties to our recent case of Nelson v. Superior Court, 184 Cal.App.3d 444, 229 Cal.Rptr. 94, a case which also presented for review in an original proceeding the propriety of the trial court's order which denied a motion to compel where the object of discovery was very similar to what has been sought in the case here. One of the reasons why we upheld the trial court's order was that the moving plaintiff had "made no showing whatever that the request for production of the accident investigation reports were reasonably calculated to lead to discovery of admissible evidence." (Id., at p. 450, 229 Cal.Rptr. 94.)