Investigation of Material Requirements for Highway Guardrail Systems (2022)

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1   The predominant standard used by the states for specifying corrugated sheet steel compo- nents for nonproprietary W-beam and thrie-beam guardrail systems is AASHTO M 180-18, Standard Specification for Corrugated Sheet Steel Beams for Highway Guardrail (the most recent version of AASHTO M 180), which is used along with associated AASHTO, American National Standards Institute (ANSI), American Society of Mechanical Engineers (ASME), and American Society for Testing and Materials (ASTM) standards. Recent updates in industry stan- dard practice and materials development have created a need to revise AASHTO M 180-18 as well as to expand its scope to include additional guardrail components. Manufacturers and hardware suppliers use significant time and resources to provide guard- rail materials according to one state agency’s design and material standards, only to start the process all over again to satisfy another state’s specifications. Such inconsistency often leads to increased fabrication costs for hardware suppliers that are ultimately passed along to transpor- tation agencies. It is anticipated that ensuring better consistency in roadside safety hardware specifications will increase competition in the supply chain, which will in turn reduce the costs to transportation agencies. Also, with the recent heightened focus from the public on roadside safety, it is imperative that transportation agencies be able to assure the public that they are specifying and using correct materials in the construction of roadside safety barriers. Therefore, improving consistency for specifying material properties and coating processes for guardrail components will provide an increased level of confidence that the materials being used are cor- rect and appropriate. 1.1 Project Objective The objectives of this project were to perform a comprehensive review of AASHTO M 180-18 and its associated AASHTO, ASTM, ANSI, and ASME standards and to propose needed revi- sions to bring the specifications into conformance with current requirements and the state of practice for highway guardrail systems. The primary focus of the project was to make additions and revisions to M 180-18 to fill gaps and address deficiencies in the current specification. The result of this work will be a more thorough, consistent, and up-to-date set of specifications within AASHTO M 180 that will improve consistency for manufacturers, states, and other trans- portation agency users. 1.2 Background AASHTO is a 100+ year-old association of the chief engineers of the departments of trans- portation (DOTs) of each of the states, the District of Columbia, and Puerto Rico. AASHTO “advocates transportation-related policies and provides technical services to support states in C H A P T E R   1 Introduction

2 Investigation of Material Requirements for Highway Guardrail Systems their efforts to efficiently and safely move people and goods” (Highway Safety Information Systems 2019). One of AASHTO’s important roles is developing highway design, maintenance, and operation policy manuals that are used as national standards of care in all aspects of highway design, construction, operation, and maintenance. AASHTO also develops and maintains material specifications for a wide variety of highway construction materials. The AASHTO Committee on Materials and Pavements’ (COMP) strategic plan was approved by the Strategic Management Committee in September 2018. Goal 1 in the strategic plan is “to develop and maintain materials standards. . . . COMP prepares, publishes, and keeps current through its yearly technical and committee meetings: (1) specifications for materials used in the construction and maintenance of all transportation facilities including highways, bridges, and structures; and (2) specifications for standard methods of sampling and testing such materials and other items incidental to construction, maintenance, preservation, and operation of such facilities” (AASHTO 2018a). AASHTO M 180 is the Standard Specification for Corrugated Sheet Steel Beams for High- way Guardrail and is maintained by the COMP Technical Subcommittee 4d – Safety Devices. AASHTO M 180 defines the strength, geometrical properties, and coating requirements for generic (i.e., nonproprietary) W-beam and thrie-beam guardrails, transitions, end sections, and some associated connectors and parts. AASHTO M 180-18 is the most recent edition of this standard; however, earlier editions of this document have served the roadside safety industry and the traveling public for nearly 60 years, going back to the 1961 publication of the AASHTO Materials Specifications.