Effect of Compliance Reviews on Out-of-Service Rates of Region 5 Carriers: A Study


Vikram Khosa, Vladimir Cherkassky

July 1998

Report no. MnDOT 1999-27



A preliminary analysis of the inspections data revealed low OSS rates based on inspection records--across all level of inspection--for the years 1993-94, indicating defective collection/interpretation of data and thereby invalidating any OOS rate analysis for this time period. Also, it was found that Level 1 and 2 inspections together constitute nearly 80 percent of all inspections records, thus marginalizing the effect of the other levels of inspection on the final results of this analysis. The results of both the short-term and long-term effects of OOS rate analysis suggest an overall positive effect of the Compliance Review program on the reduction of OOS (Event and Violation) rates of the carriers. These results are consistent over the rest of the time period (1995-97) and across three levels of inspection (Levels 1, 2, and 3). The conclusions drawn about the nature of the effects of a Compliance Review could be much better validated if the currently spurious inspections data for the years 1993-94 were restored, or a fresh analysis using later available data (1997-98) were carried out based on the same algorithms.

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