Bridge Rating Practices and Policies for Overweight Vehicles (2006)

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3BACKGROUND Trucking is an important transportation mode for the economy of this country. Trucking is regulated not only by federal rules but also by state and sometimes local legislation and policies. In particular, trucks that exceed the legal limits for dimension and weight are required to have a permit to operate, which is referred to as an oversize/overweight (OS/OW) permit. The criteria used in the permitting process are not uniform among different jurisdictions. Nonuniformity has been a concern for the trucking industry, with respect to different lengths of time needed to have a permit review completed, different results of permit application for the same load, the need to change the vehicle configuration to transport the same goods through dif- ferent states, etc. Note that some of the factors contributing to nonuniformity are difficult to control. For example, many states have thresholds for the definition of “superload” that re- quire evaluation of all the bridges on the planned route. These thresholds are often defined by state legislation or policies es- tablished at different times in the past. Making them uniform can be difficult if not impossible. In permit review, particularly for overweight trucks, bridge capacity is important. As opposed to pavements for which truck wheel loads are critical factors, bridges are required to carry the entire truck load, depending on the re- lation between the vehicle and the bridge lengths. When a bridge on the route is determined to be unable to carry the load, the permit cannot be issued. Therefore, bridge capacity sometimes becomes the weakest link in issuing a permit. Some state permitting offices have worked with industry toward a goal of increased uniformity in permitting over- weight and oversize trucks within and between states. His- torically, most of that effort has been focused on state laws and regulations governing motor carriers. Relatively little attention has been directed toward the contribution of state bridge evaluation practices and procedures toward achieving this goal. This issue is a focus of the present study. Bridge evaluation for permit review is very much related to bridge load rating practice, and both may vary between and within states. Choice, interpretation, and limitation of the specifications, software tools, treatment of nonstandard con- figurations (such as axle gages and multiple-lane configura- tions), and allowances for in-place dead loads are examples of those areas where variation in practice often exists. The extent of these differences and their impact on the goal of more uniform permitting is not well understood. Identifying and documenting the different bridge evaluation practices used for OS/OW vehicle permits are considered to be an important step toward more uniform permitting. This synthesis study focuses on overweight vehicle per- mit review that requires bridge evaluation. However, other potentially relevant subjects are also addressed to have a complete understanding of the subject. OBJECTIVE The objective of this synthesis study is to gather information on state bridge rating systems, bridge evaluation practices, and permit policies, as they relate to overweight and oversize vehi- cles. The information is intended to help in the understanding of the reasons for nonuniformity in permit practices, and thus to encourage the development of possible solutions. APPROACH This study was approached using the following steps. • A survey was conducted of transportation agencies at the state level in the United States and their counterparts in Canada to understand the operations of permit review and issuance and related bridge evaluation and load rat- ing. The questionnaire was initially sent to four states and then further revised to address the issues and con- cerns thereby generated. The final questionnaire was distributed to state-level transportation agencies in the United States and several agencies in Canada and is given in Appendix A. A total of 44 agencies from United States and 10 from Canada returned the ques- tionnaire and their responses are summarized and dis- cussed in this report. • A literature search was performed that included the use of the World Wide Web to understand previous relevant work with regard to bridge evaluation for truck permit issuance. The identified research reports, papers, and other publications were reviewed and are summarized and discussed in this report. • Telephone interviews were conducted with targeted or- ganizations and individuals to supplement the informa- tion acquired through the survey and literature review. CHAPTER ONE INTRODUCTION

Those organizations, individuals, and information sources contacted included: – Hauling companies and construction and crane rental companies that routinely request permits to move overweight loads: the Specialized Carriers and Rigging Association (SC&RA), Midwest Special- ized Carriers, Intermountain Rigging and Heavy Haul, Keen Transport, and Commercial Vehicle Safety Alliance. – States that are perceived to have large load limits: Kentucky, Michigan, and North Dakota. – Southeastern Association of State Highway and Transportation Officials (SASHTO) Multi-State Permit Group. – AASHTO BRIDGEWare Task Force. – Illinois Department of Transportation (DOT) sur- vey on Load and Resistance Factor Rating (LRFR) usage. – New England Transportation Consortium (NETC). 4 – State transportation agency engineers and consulting engineers. • The information received was then analyzed and synthesized. ORGANIZATION This synthesis report has five additional chapters. Chapter two presents a brief review of the relevant studies identified in the literature search. Chapter three provides a summary of nonuniformity observed in permit types, processes of permit review, personnel assigned to permit review, etc. Chapter four discusses more details of bridge evaluation and rating as prac- ticed in the United States and Canada that may be the causes of the nonuniformity observed. Chapter five presents previ- ous and current efforts to reduce nonuniformity in permit issuance and other relevant practices. The final chapter (chap- ter six) summarizes the study, draws several conclusions, and suggests future research relevant to the focused subject.