Roadside Hardware Replacement Analysis: User Guide (2021)

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2 27-inch guardrail with 31-inch guardrail? Waiting until the 27-inch guardrail is “damaged beyond repair” may mean the guardrail stays in service for decades (1). Is that acceptable? The recently installed non-MASH 27-inch guardrail probably also has Report 350 guardrail terminals and guardrail-bridge rail transitions that are also in good repair since they were only recently installed. When should they be upgraded to MASH 2016? Is the priority for upgrading the terminals the same as upgrading the w-beam guardrail? These are the types of questions that highway agencies face in developing a “process to replace existing highway safety hardware” (1). Establishing priorities for upgrading roadside hardware is not a new activity in roadside design. A similar situation occurred when NCHRP Report 350 appeared in the 1990s (5). After NCHRP Report 350 was published, the FHWA incorporated it as one of the guides and references for design standards for highways in 23 CFR Part 625 (6). In 1998 AASHTO and the FHWA negotiated an implementation agreement with specific dates for each type of roadside hardware much like the MASH implementation agreement (7). The 1998 AASHTO-FHWA agreement also categorized hardware into three groups: hardware used in new construction, hardware used on 3R project, and systemwide replacements. There were specific dates for upgrading each type of hardware for each of the three categories. For example, systemwide replacement was not required for most hardware meaning pre-Report 350 hardware that was in place in the field could remain until the roadway was reconstructed or a 3R project was programed. The exception to this were Category III work zone devices which had to be replaced systemwide by 1 October 2002. What was meant by “3R” projects was explained in note 3 of the memo. New construction was defined as “a new installation of a feature … where none exists” (7). Upgrading the hardware for an existing feature that had to be “moved, reconstructed, or extended” in a reconstruction project was recommended although agencies, as in the MASH implementation agreement, were encouraged to develop policies to address these situations (7). The need, therefore, to establish priorities for upgrading existing hardware to hardware that meets newer crash testing guidelines occurs periodically in roadside safety and a method for more systematically implementing priorities for upgrading is a recurring need. In the past, policies have been developed primarily using engineering judgement rather than a systematic assessment of the effectiveness and economics of upgrading existing hardware. The purpose of this user manual is to present a method that the highway agencies can use to prioritize upgrading existing roadside hardware to new crash test requirements. The roadside hardware covered by MASH 2016 includes guardrails, median barriers, bridge railings, transitions, guardrail terminals, crash cushions, breakaway sign supports, luminaire supports and work zone hardware. Upgrading all of these types of devices to MASH 2016 is a large undertaking that will take many years and significant funding to accomplish. Since everything cannot be accomplished at once, user agencies need a means for developing hardware upgrade policies that implement MASH 2016 hardware in a systematic, staged, and prioritized manner. This manual presents a systematic data- driven method that user agencies can use to establish upgrading priorities. Implicit in this discussion is the recognition that just because crash test procedures and evaluation criteria change does not mean that hardware developed using earlier criteria suddenly becomes unsafe. The process of improving roadside safety hardware is an incremental process where each generation of hardware is thought to be slightly more effective than the previous generation. Prioritizing upgrading policies involves assessing the incremental reduction in the risk of fatal and serious injury expected from upgrading roadside hardware and balancing that risk reduction with the highway agency costs of upgrading the hardware such that funds are expended to maximize overall

3 network safety. Appreciating the underlying risk reductions and costs of upgrading are fundamental to developing effective upgrading policies. The systematic data-driven process for roadside hardware replacement analysis described in this user guide is not meant to be prescriptive but informative. Engineers are likely to use this process as part of the decision-making process in combination with engineering judgement, agency experience, in-service performance history and other highway agency objectives. The method presented herein is just one of several considerations that should be included in making roadside hardware replacement decisions. A highway agency may also consider ease of maintenance issues, stock-piling materials, project scheduling, contractor familiarity with various designs and other issues. For example, an agency may elect to replace existing hardware that is otherwise in reasonably good repair because it is approaching the end of its service life and another project at the site in the near term is unlikely. Similarly, sometimes numerous spot repairs (e.g., blockout replacements, post replacement, post realignment, replacement of individual guardrail panels) might be needed to return a system to crash-ready condition and the agency may elect to simply replace with new hardware. The method presented herein, therefore is one facet of the decision-making process but could be used in conjunction with other considerations. 2 APPLICABILITY This Roadside Hardware Replacement Analysis User Guide can be used by highway agency engineers and their consultants when evaluating and planning individual or systemwide projects where existing roadside hardware is in good condition and appropriately located according the AASHTO Roadside Design Guide or highway agency roadside design policy but does not meet the evaluation criteria of MASH 2016 (8). A typical example of such projects include pavement restoration projects on roadways with existing guardrails and guardrail terminals where the roadside hardware is incidental to the primary objective of the construction. This method can also be used to develop policies for determining when damaged hardware should be upgraded to MASH 2016 or replaced in-kind. 3 PROCEDURE The roadside hardware replacement analysis process is comprised of 22 steps organized into four parts: • Relative risk assessment of existing hardware (Steps 1 through 8), • Relative risk estimate for replacement hardware (Steps 9 through 11), • Project details (Steps 12 through 17) and • Economic analysis (Steps 18 through 22). A brief description of each step is contained in Table 1 and a more detailed description of each step is contained in the following subsections. In executing this procedure, the analyst should assume the default decision would be to upgrade and replace the hardware. Where assumptions are necessary, the analyst should assume conditions most favorable to replacing the hardware. This ensures that if replacement is not recommended by the procedure, that the decision to leave existing hardware in place is not likely a good use of highway agency funds.