A Study was initiated in May of 1990 to investigate the problem of trucks bypassing or avoiding weigh/enforcement stations in Kentucky. A literature review identified two major studies (Wisconsin and Florida) on the subject, both of which are summarized in this report. In addition, a 1989, limited-scope study of truck bypassing of weigh stations in Kentucky was reviewed and summarized.

The primary data collection effort for this study took place in the fall of 1990, centered around the Simpson County enforcement station on Interstate-55. Three potential bypass routes were identified. Automatic vehicle classification (AVC) and weight-in-motion (WIM) equipment was installed on 1-65 and on all three bypass routes. Data collection took place over a three-week period, with enforcement on the bypass routes during the second week.

Significant conclusions of the study include: 1) While weigh station bypassing does occur in Kentucky, there was no indication of significant numbers of trucks modifying their route choices due to enforcement activity on the bypass routes; 2) Average truck weights and the percentage of trucks overweight are higher on bypass routes than on Interstate routes, but this is not primarily a result of bypassing activity; 3) The majority of trucks on bypass routes have legitimate reasons (in terms of origin or destination) to be on those routes; 4) A high percentage of trucks on bypass routes have violations, regardless of whether the trucks have a local origin/destination along the route; 5) The most common inspection violations on bypass routes are safety-related equipment violations, followed by driver violations; 6) Temporary enforcement efforts on bypass routes can be effective and can be self-supporting through citation revenues; 7) Due to accuracy limitations, high speed WIM data may not be appropriate for certain uses.

The following recommendations were developed: 1) A statewide enforcement plan should be developed with increased emphasis on enforcement for non- Interstate routes; 2) Innovative options should be investigated to simplify or expedite weigh station operations; 3) Enforcement efforts on non-Interstate routes should be randomized and unpredictable and should include weighing of trucks; 4) Effectiveness measures should be developed and used to monitor non-Interstate enforcement efforts; 5) The accuracy of statewide WIM data should be assessed; 6) The potential for using statewide WIM data to identify problem areas and direct enforcement efforts should be explored, and a formal process should be established to foster this cooperative effort.

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.