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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
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Page 3
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
×
Page 4
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
×
Page 5
Page 6
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
×
Page 6
Page 7
Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
×
Page 7
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Suggested Citation:"Summary." National Academies of Sciences, Engineering, and Medicine. 2021. Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative. Washington, DC: The National Academies Press. doi: 10.17226/26221.
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Page 8

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Summary Most natural gas produced and consumed in the United States is transported long-distance through a nationwide network of transmission pipelines, but the country’s pipeline capacity is limited in some regions and pipelines are an impractical option for transportation outside North America. For transportation by other modes, natural gas can be cooled to a liquid state to produce a much denser liquefied natural gas (LNG). Bulk shipments of LNG have been transported by water in marine tankers and by highway in tank trucks for decades. LNG has not been transported to any significant degree by railroad in the United States. Except for some individually approved shipments in portable tanks on flatcars, LNG had not been authorized by federal safety regulations to be transported by rail. However, in response to a 2017 petition from the Association of American Railroads and an April 2019 presidential executive order, the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) and Federal Railroad Administration (FRA) initiated a rulemaking to allow LNG to be transported by rail tank cars designed for cryogenic hazardous commodities. A final rule authorizing the movements was approved in July 2020, but stipulated that the tank cars used to move other types of cryogens would need to be redesigned with a thicker outer tank (9/16 inches versus 7/16 inches) composed of higher-grade carbon steel and the trains transporting these tanks would be subject to requirements for enhanced braking, monitoring train location and tank pressure, and safety and security route planning. The rule calls for modifications of the outer tank to increase puncture resistance in the case of a derailment. To support development of the final rule and inform subsequent decisions to ensure the safe movement of LNG by rail, PHMSA and FRA jointly established an LNG-by-rail task force (Task Force) during January 2020. The Task Force was given 15 research, testing, and analysis tasks, each intended to help PHMSA and FRA “know, predict, reduce, and prepare for” any significant risks that could arise from LNG’s transportation by rail. The tasks related to these four purposes are listed in Table S-1. Concurrently, Congress directed PHMSA to commission a study by the National Academies of Sciences, Engineering, and Medicine (the National Academies) on the safe transportation of LNG by rail tank car. 1 While development of the final rule proceeded at a pace that would the preclude the study from informing it, PHMSA and FRA nevertheless viewed the study mandate as an opportunity for a review of the Task Force’s activities by an independent committee of experts in hazardous materials transportation safety. 1 Further Consolidated Appropriations Act of 2020: Committee Print of the Committee on Appropriations, U.S. House of Representatives, P.L. 116-94, 1231, 2020, https://www.govinfo.gov/content/pkg/CPRT- 116HPRT38679/pdf/CPRT-116HPRT38679.pdf. PREPUBLICATION COPY—Uncorrected Proofs 1

TABLE S-1 Tasks in the Liquefied Natural Gas (LNG) Task Force Project Plan as Categorized by the Pipeline and Hazardous Materials Safety Administration and Federal Railroad Administration KNOW the Risk PREDICT the Risk REDUCE the Risk PREPARE for the Risk Empirical Review Evaluate Punctures Electronically Emergency Responder of International and Derailment Controlled Opinions and Needs LNG Rail Simulation Modeling Pneumatic Brakes Transportation Loading/Unloading Worst Case Scenario Train Operational LNG Educational and Safety Assessment Model Controls Outreach Plan Quantitative Risk Safety/Security Route Automated Track Assessment Risk Assessment Inspection Program Full-Scale Impact Train Energy Testing Dynamics Simulator UN-T75 Portable Modal Conversion Tank Fire Testing Between LNG by Truck and Rail PHMSA and FRA negotiated a Statement of Task with the National Academies that consists of two study phases, with each phase producing a report. The full Statement of Task for the two-phase project is provided in Chapter 1. In the first phase, the study committee is charged with reviewing the Task Force’s completed, ongoing, and planned tasks. Specifically, the committee is asked to examine the quality, completeness, and relevance of the research, testing, and analysis tasks and to provide advice on how they could be improved, recognizing that the two agencies will need to remain vigilant in monitoring the effectiveness of the requirements in the rule authorizing movement of LNG by rail. This report is the product of this first phase, and is therefore limited to reviewing the plans and progress of the Task Force. While the Task Force’s work finished in 2020, some tasks remain pending and therefore may be modified on the basis of the review’s findings. Likewise, there may be opportunities to strengthen the analyses of the results of completed tasks to better inform future decision making and research, testing, and analysis activities. No longer limited to examining the Task Force’s research, testing, and analysis activities, the second phase of the project will provide a more in-depth review of the safe transportation of LNG, including an examination of the applicability of existing guidelines for emergency responses to LNG rail incidents and safety assurance measures that address a range of risk factors such as incidents caused by deliberate acts, human factors, or track component defects. The second phase is scheduled to be completed in mid-2022. STUDY APPROACH The committee was not tasked with conducting its own analyses, but rather to exercise its expert judgment on the basis of what it learned from PHMSA and FRA briefings and materials describing and documenting the outcomes, plans, and status of the Task Force’s work. The documents and briefings explained the methodologies used in conducting the research, analyses, modeling, and testing for each task and how the results are being, or will be, integrated into the PREPUBLICATION COPY—Uncorrected Proofs 2

safety assurance mission of PHMSA and FRA. In its review, the committee focused on the Statement of Task’s emphasis on assessing the initiative’s relevance, completeness, and quality to support PHMSA, FRA, and industry decision making going forward to ensure the safety of LNG rail movements and monitor the efficacy of the requirements in the new rule authorizing them. In treating relevance first, the committee considered how directly each of the 15 tasks aligns with the transportation of LNG by rail tank car. The six tasks that addressed LNG specifically were considered to be the most relevant, and thus grouped and examined together for completeness and quality. The groupings are shown in Figure S-1. An example is the Worst-Case Scenarios Model, which examines how the hazard characteristics of LNG would affect the type and severity of the consequences of a rail incident. Next, in terms of relevance, the committee examined the tasks that concern rail transportation of hazardous materials more generally, an example being the Safety and Security Route Risk Assessment task. Finally, the committee considered the completeness and quality of tasks that concern railroad safety assurance generally, such as the task on the Automated Track Inspection Program (ATIP). It merits noting that this regrouping of the tasks based on their specific relevance to LNG and its safe transportation by rail is not a prioritization of the 15 tasks with respect to their overall significance for understanding and reducing risk, but rather a reflection of the committee’s charge to examine the specific risks associated with LNG. The three groupings provide an organizing framework for the report chapters. The groupings reveal how the results and information from one task are intended to inform others. Figure S-1 maps the connections among the individual tasks to show these interrelationships. The tasks to the left involve gathering empirical data; the tasks in the middle use the collected data to create models; and the tasks to the right use the simulation results in analyses. PREPUBLICATION COPY—Uncorrected Proofs 3

FIGURE S-1 Relationships between the 15 tasks by grouped by relevance to LNG transportation by rail. NOTES: The six tasks in green are specifically relevant to LNG by rail. The six tasks in yellow are relevant to hazardous materials transport by rail. The three tasks in blue are broadly relevant to railroad safety assurance. SUMMARY ASSESSMENT Considering the large and varied number of tasks, their interdependencies, and the major disruptions caused by the COVID-19 pandemic to the execution of several tasks, the committee believes that the Task Force’s program is comprehensive as planned. The incomplete status of many of the tasks is justified under the circumstances, particularly because of the interconnections among the tasks. The committee observes that the Task Force’s efforts benefited from an ability to make effective use of a number of longstanding programs at PHMSA and FRA, such as the tank car impact testing and automated track inspection programs. Nevertheless, there are areas, in the committee’s view, where more complete treatment is warranted, and where the basis for choices about the structure and execution of the tasks, such as those pertaining to experimental design and the selection of parameters for modeling and other analyses, has not been made sufficiently clear to assess the applicability and validity of the results. In a few cases where the grounds for such choices are explained, the committee raises questions about them and offers some suggestions for improvement. PHMSA and FRA wisely capitalized on a number of longstanding and high-quality research and testing programs to adapt them to the questions surrounding the safe movement of LNG by tank car. For instance, FRA’s ATIP builds on approximately four decades of developing track geometry measurement vehicles equipped with state-of-the-art technology for data acquisition about track infrastructure conditions. Likewise, PHMSA has decades of experience PREPUBLICATION COPY—Uncorrected Proofs 4

collaborating with and supporting the emergency response community. PHMSA conducts regular outreach activities and has long supported identified responder needs through funding to state, local, and industry entities for transportation-related hazardous materials planning, training, and exercises. In addition, the tasks on Full-Scale Impact Testing and Punctures and Derailment Simulation Modeling consist of programs that have been validated experimentally and used to support previous tank car design efforts. Notably, the decision to require a thicker outer tank for the newly specified cryogenic tank car was based on the punctures modeling. Knowing that the Task Force commenced its work during the outbreak of the pandemic, the committee fully expected to find tasks that required physical testing and site visits to be incomplete or pending, and that these delays would, in turn, lead to the incomplete status of other research and analytic tasks. Notably, impact testing on a tank car filled with liquid nitrogen, which is needed for understanding the puncture resistance of the newly specified DOT- 113C120W9, will not take place until late 2021. The results from these pending tests are expected to inform the tasks on the Worst-Case Scenarios Model, Punctures and Derailment Simulation Modeling, and Train Energy and Dynamics Simulator tasks. Other tasks were similarly postponed and thus lacked sufficient information for the committee’s review. For example, site visits associated with Train Operational Controls have been postponed, and the analysis for the Modal Conversion Between Truck and Rail is pending submission of a specific shipping route. Although the Safety and Security Route Risk Assessment task is also delayed, the committee was unable to review the relevant security factors that will be considered because the Task Force could not share sensitive information related to the route assessment. The following are examples of where the committee believes the Task Force should offer a clearer rationale for the choices made in designing and executing tasks, particularly with respect to several of its testing and modeling tasks: • Full-Scale Impact Testing—Impact testing is conducted to understand the baseline puncture resistance of a tank car design given certain conditions. Because the outer- tank closure seams appear more vulnerable to impact than the center of an outer tank plate (or the post-weld heat treated seam of a tank car), it would be helpful to know why the Task Force did not test for impacts on this part of the tank and whether it intends to do so in follow-on tests. • Portable Tank Fire Testing—The design of the fire tests involved choices about pool fire size and shape and orientation of the tank with respect to the fire. The test also used a portable tank on a flatcar rather than a tank car. The fuel used for the pool fire was liquefied petroleum gas instead of LNG. These may have been necessary and valid choices under the circumstances (e.g., in the absence of a manufactured newly- specified tank car and because of testing safety concerns about LNG). However, the choices are likely to affect the relevance of the testing to predictions of the survivability of a DOT-113C120W9 tank car engulfed in an LNG pool fire. The Task Force should provide a detailed accounting of these choices that could have bearing on that relevance. • Worst-Case Scenarios Model—The task uses 40 mph as the speed of a train before derailment based on the results from the puncture and derailment simulation task. Because the task is intended to represent worst-case scenarios, the committee questions why this particular speed was selected rather than the 50 mph speed also PREPUBLICATION COPY—Uncorrected Proofs 5

run in the simulations. Several other choices warrant further explanation as well, including the exclusion from the scenarios of the heat flux from a jet fire, cascading cryogenic damage from partial submersion in a pool of LNG, and heat flux from a pool fire to the adjacent tank cars. While there may be valid reasons for excluding these conditions, they should be documented to provide a more convincing case of the task’s credible representation of worst-case scenarios. • Quantitative Risk Assessment (QRA)—The task references a previously conducted QRA for unit train movements of LNG tank cars on routes for a single origin– destination pair. The QRA did not consider LNG movements in a manifest train (i.e., mixed cargo) or under other conditions not represented by those found on the routes of this single origin–destination pair. The committee understands the challenge of conducting QRAs in a generalized manner without specific routes and train configurations that can be subject to analysis. However, the conduct of QRAs for more varied scenarios for LNG routings and train configurations, even if hypothesized, would provide insights into the conduct of QRAs for LNG by rail movements on a national basis. • Modal Conversion Between Truck and Rail—The Task Force completed an initial examination of the risk implications of diverting LNG traffic from truck to rail and vice versa for possible routes under a 2019 special permit for LNG by rail tank car between Pennsylvania and New Jersey. PHMSA plans to repeat this analysis when the shipper and rail carrier identify an actual route in fall 2020. Missing from this task are the risks entailed in loading and unloading operations. While the conditions during line-haul movement differ between rail and truck, thus presenting different risks, there are also differences in loading and unloading operations. In addition, train assembly and classification activities were also missing from this task. These differences warrant consideration because both are sources of injuries and fatalities in hazardous goods movement. • Train Energy and Dynamics Simulator (TEDS)—TEDS was used to simulate unit train operations over two rail routes designated for LNG transport by DOT-113 tank cars under various conditions. The simulation results produced train speed, coupler forces, lateral and vertical force ratios, and other results used in other tasks. The committee questions, however, why the model was not run using a train with distributed motive power, which is one of the operational requirements in the rule authorizing LNG by rail. Documenting the placement of the buffer car in the train is also important for assessing the predictive power of the software. RECOMMENDATIONS ON PENDING WORK Because the Task Force has already completed a significant amount of work and had a limited lifespan, the opportunities for the committee to advise are limited to suggesting improvements that can be made to the explanation, analysis, and documentation of completed work—as offered above—and recommending changes to planned tasks or to work related to LNG safety that is likely to be pursued by PHMSA and FRA in the future after the Task Force completes its work. The following recommendations are intended for this purpose. PREPUBLICATION COPY—Uncorrected Proofs 6

Portable Tank Fire Testing Recognizing that Phase 2 of the first testing task has not begun, FRA and PHMSA should make several changes to the planned testing to improve data quality and analysis. Changes that should be made include: • Modify the pool fire by increasing its size and making it circular; • Remove the flatcar from the experimental setup; • Place the tank car in a rollover orientation where the pressure relief valve will vent liquid; • Use LNG as the pool fire fuel; • Evaluate an LNG fireball and tank fragmentation in the event of a boiling liquid expanding vapor explosion to prepare emergency response personnel; and • Assess the potential for cryogenic damage cascading to adjacent tanks by evaluating topography surrounding the rail tracks that could support pool formation. Worst-Case Scenarios Model Enhancing the modeling for worst-case scenarios will require inputs from the pending tasks on full-scale impact test, punctures and derailment simulation, and fire testing. Once these pending tasks are completed and data are collected and analyzed for incorporation, PHMSA and FRA should further update the model for worst-case scenarios in the following manner: • Provide upper bound values of predicted number of punctures to identify the worst- case release rather than using nominal values; • Use a train speed of 50 mph for the predicted number of punctures rather than the 40 mph used; • Evaluate the heat flux from a jet fire from a punctured tank and impinging on an adjacent tank; • Evaluate the total amount of LNG that could potentially be released from cascading damage to adjacent tank cars from partial submersion in an unignited pool of LNG and/or partial exposure to the heat flux from a pool fire; • Evaluate the potential hazard to emergency responders of a rapid phase transition from an LNG spill onto a body of water, considering that track infrastructure commonly runs along rivers; and • Evaluate explosion hazards from an unignited spill of LNG resulting in vapor dispersion in an environment with confined or congested spaces. Modal Conversion Between Truck and Rail PHMSA should add loading and unloading operations and train assembly and classification activities to the assessment of the risk of LNG by rail as compared with highway when repeating this task in fall 2022. PREPUBLICATION COPY—Uncorrected Proofs 7

CONCLUDING COMMENT The committee found it challenging to review and integrate the documentation of the 15 tasks. That documentation and its integration have been complicated by the expedited schedule of tasks and the subsequent interruptions caused by the pandemic. It will be important, however, for the Task Force’s work to be carefully documented and the purpose and results of the tasks appropriately connected. This report tries to provide some of that integration, but gaps in the documents and pending tasks will need to be addressed first. In the committee’s view, the overarching safety assurance enterprise would be improved by establishing a framework for systematically integrating and reporting the results from the tasks. Ensuring the safety of LNG by rail, like all hazardous materials shipments, is an ongoing process that will require continued monitoring and adjustment of practice and regulations. PREPUBLICATION COPY—Uncorrected Proofs 8

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Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative Get This Book
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Liquefied natural gas (LNG) has not been transported to any significant degree by freight railroads in the United States. When the Further Consolidated Appropriations Act of 2020 was enacted, it directed the Pipeline and Hazardous Materials Safety Administration (PHMSA) to enter into an agreement with the National Academies of Sciences, Engineering, and Medicine (NASEM) to convene a committee of independent experts to study the safe transportation of LNG by rail tank car.

TRB Special Report 339: Preparing for LNG by Rail Tank Car: A Review of a U.S. DOT Safety Research, Testing, and Analysis Initiative, from TRB and NASEM, finds that PHMSA’s task force presented a comprehensive plan of work that built on longstanding safety programs, as well as surfacing opportunities for future research. The findings in the report will serve as a good base for the second phase of TRB’s phased continued study of the issue. The next phase will be informed by this technical report; will consider experience transporting LNG in other modes, including marine tankers and cargo tank trucks; and will examine the applicability of existing emergency response plans, protocols, and guides for responding to any possible hazardous materials incidents of transporting LNG by rail.

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