A Probability Model of Lockage Stalls and Interferences
A model of lock failures as manifested by stalls or interferences and specified in terms of a logit formulation is presented in this paper. Stalls or interferences that correspond to commercial tow and recreational vessel lockages and that result from lock hardware problems or to testing or maintaining the lock or its equipment are first considered. The expected frequency of such lock failures relative to the number of commercial tow and recreational vessel lockages is then explained. These expected frequencies can be viewed as measures of reliability or interpreted as the probability that such failures will occur on any given commercial tow or recreational vessel lockage. The qualitative results corresponding to the underlying variables are consistent with expectations. The usefulness and flexibility of the model in evaluating changes in the values of these variables is demonstrated. Among other things, this demonstration suggests that many major maintenance projects relating to lock chambers can be evaluated by their consequent effect on lock failure probabilities. It is demonstrated that the extent of the renewal of a chamber in response to major maintenance can be calculated.