Review of U.S. Department of Transportation Truck Size and Weight Study: First Report: Review of Desk Scans (2014)

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39 ENFORCEMENT AND COMPLIANCE The MAP-21 [Section 32801(a)(3)] specification for the CTSW study enforcement analysis asks the study to: (3) evaluate the frequency of violations in excess of the Federal size and weight law and regulations, the cost of the enforcement of the law and regulations, and the effectiveness of the enforcement methods. The enforcement desk scan and project plan indicate that the USDOT study team interprets this part of the MAP-21 study charge as requiring two assessments: (a) evaluating the violation frequency and enforcement cost and effectiveness for the current fleet of trucks operating in the United States and (b) making similar estimates for the alternative configurations considered in the CTSW study. Is the Desk Scan Thorough? The enforcement desk scan presents the material reviewed in a logical and useful topical organization, defines the scope and criteria of its review, and systematically summarizes the results of the past studies. These features of the desk scan could serve as a model for the desk scans in the other study areas. The desk scan reviews 76 studies and other documents published since approximately 2000, organized into eight topic areas: extent of the compliance problem, traditional approaches to enforcement, effect of regulatory changes on enforcement, enforcement costs, enforcement benefits, effectiveness of enforcement, application of enforcement and compliance technologies, and alternative approaches for achieving compliance. The summaries provide a thorough consideration of the topic areas. The committee has identified a few missing studies, as discussed below. One area to which the desk scan pays little attention is the prospect for more rigorous

40 enforcement using new technologies. Examples of the increased possibilities for technology in truck size and weight enforcement include USDOT’s Smart Roadside Initiative (SAIC n.d.), which aims to connect and share data among vehicles, motor carriers, enforcement resources, highway facilities, intermodal facilities, toll facilities, and other nodes on the transportation system to improve motor carrier safety, security, operational efficiency, and freight mobility. Is the Desk Scan Missing Literature, Case Studies, Models, or Data That Would Help Achieve the Study Goals? Overall, the information available from the sources reviewed is insufficient for measuring the cost and effectiveness of enforcement. The authors acknowledge this difficulty in the introduction to the desk scan (p. 1): “The review emphasizes the enforcement of truck size and weight limits; however, distinguishing enforcement activities concerning truck size and weight from those directed at safety or credentials regulations is not always possible.” The lack of necessary data is the consequence of long-standing problems associated with weight enforcement programs. Adequate performance metrics for the success of state enforcement programs are not available. Analyzing state data that are likely influenced by inconsistent state laws will be difficult. As a consequence, at best, only broad estimates of the effectiveness of enforcement efforts may be possible in the CTSW study. More detailed documentation of the limitations of the data sources to be used in the CTSW study would have been appropriate in the desk scan. In particular, accurate depiction of the true level of compliance through use of WIM data is challenging. The project plan makes apparent that the CTSW study team recognizes this difficulty, but how the analyses proposed will compensate for the data problems is not evident. It will be necessary to analyze weight distributions from WIM stations where no enforcement occurs and compare them with distributions from stations at locations with vigorous enforcement. This will provide insight into the frequency and weight distribution of trucks diverting to secondary routes to avoid enforcement. For best results, selected WIM sites should use the same WIM

41 technology and be of approximately the same age, or calibrated similarly, to provide comparable data. The desk scan does not cite data sources for potentially important categories of enforcement costs, in particular, costs of increased inspection times that may be required for new vehicle configurations and costs of expansion or replacement of existing scales and inspection areas that may be needed for handling larger and heavier trucks. The review does not cover economic research on optimal fine levels. For example, Kenkel (1993) shows that optimal fines should recover the full costs of harm and enforcement. Similar reasoning suggests that permit fees should recover the full costs of accelerated rehabilitation and repair projects, including construction, congestion, safety, and environmental costs. Does the Desk Scan Interpret the Literature Reviewed Correctly? The overall interpretation of the literature in the desk scan is reasonable. In general, a more critical appraisal of all studies cited would provide a stronger basis for selecting approaches in the study plan. The desk scan uncritically reports a statement of the 2002 TRB truck size and weight study (TRB 2002) that rigorous weight enforcement could increase overall truck shipping costs. The proceeds of illegal activities should not be regarded as benefits to society in benefit–cost analysis of enforcement programs (Trumbull 1990). Does the Desk Scan Synthesize the Literature and Draw Appropriate Conclusions? The organization of the literature into topical areas and the summaries in Tables 1–4 and 6–9 that identify the key documents in each topic area and the contribution of each to the CTSW study are useful first steps toward a synthesis and conclusions. However, syntheses of quantitative results (e.g., statements about the likely range values of metrics of enforcement effectiveness and enforcement costs, derived from the estimates in the sources reviewed) are not presented.

42 References Kenkel, D. S. 1993. Do Drunk Drivers Pay Their Way? A Note on Optimal Penalties for Drunk Driving. Journal of Health Economics, Vol. 12, No. 2, pp. 137–149. SAIC. n.d. Smart Roadside Initiative (SRI). http://www.smartroadsideinitiative.com/. TRB. 2002. Special Report 267: Regulation of Weights, Lengths, and Widths of Commercial Motor Vehicles. National Academies, Washington, D.C. Trumbull, W. N. 1990. Who Has Standing in Cost–Benefit Analysis? Journal of Policy Analysis and Management, Vol. 9, No. 2, pp. 201–218.