National Academies Press: OpenBook

Transit Safety Risk Assessment Methodologies (2021)

Chapter:Chapter 3 - Survey Results

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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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Suggested Citation:"Chapter 3 - Survey Results." National Academies of Sciences, Engineering, and Medicine. 2021. Transit Safety Risk Assessment Methodologies. Washington, DC: The National Academies Press. doi: 10.17226/26449.
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20 Survey Results Forty-three agencies responded to either the targeted (21 agencies) or the non-targeted (22 agencies) survey. Of the 43 agencies, one participating agency did not have personal knowl- edge of the agency’s SRA methods, and three agencies reported not conducting any type of SRA. The agency background section summarizes agency information provided by agency representatives who had knowledge of organizational SRA, while the methodologies section focuses on the 39 agencies that use some type of SRA. Agency Background Figure 11 presents the number of participating agencies that offer a specific mode (gray bar) and the number of agencies that offer a specific mode through a contract provider (black bar). Bus was the most commonly offered mode followed by on-demand services (paratransit), rail, microtransit, some other mode, and trolley. On-demand service (paratransit) was the mode most commonly offered to the public via a contract provider. Figure 12 presents the distribution of organizations by the number of modes offered. All but five agencies are multimodal. The mean number of modes offered was 2.7, while the median was 3.0. The white italicized number in each Figure 12 bar represents the mean number of the modes operated by a contract provider. Figure 13 presents the distribution of organizations by the number of modes offered to the public via a contracted provider. Approximately half of the organizations offer services to the public via a contractor, while approximately half do not. The mean and median number of contract modes offered was 1.0. The white italicized number in each Figure 13 bar represents the mean number of the modes offered to the public. Figure  14 presents the mean number of vehicles operated in annual maximum service (VOMS) by mode. The data suggest that bus service is characterized by the largest VOMS, while microtransit is characterized by the smallest VOMS. Figure 15 presents the many combinations of modes offered to the public by participating transit agencies. Bus and paratransit were the modes most often mentioned in combination, with bus, rail, and paratransit not far behind. Methodology Nearly 90 percent of agencies that use some type of SRA methodology reported using only one method. Four agencies reported using two methods, and one agency reported using three or more methods. See Figure 16 for more details. C H A P T E R 3

Survey Results 21   Figure 11. Contract and total service. Figure 12. Number of modes offered.

22 Transit Safety Risk Assessment Methodologies Figure 13. Number of modes contracted. Figure 14. Mean vehicles operated in annual maximum service (VOMS) by mode.

Survey Results 23   Figure 15. Mode combinations. Figure 16. Number of Safety Risk Assessment methods used.

24 Transit Safety Risk Assessment Methodologies Figure 17 presents the number of agencies using each SRA method. The data suggest that the MIL-STD-882 is the most often used, with the modified MIL-STD-882 and “other” methods not far behind. The European CSM was the least often used method. The white italicized number in each Figure 17 bar represents the mean VOMS (all modes) of agencies that use each specific SRA method. Figure 18 summarizes how participating agencies use their SRA processes. The data suggest that the SRA is most commonly used “on hazards and other safety concerns that are identified through inspections and internal audits,” followed by use “on hazards and other safety concerns reported by employees and/or riders,” and “when investigating a safety event, accident, or incident.” Nearly all organizations that reported using some type of SRA process (35 of 39) stated that they do have a level of risk that is deemed “acceptable.” The four organizations that did not have a defined acceptable level of risk were multimodal, tended not to offer services to the public via a contractor, and were likely to use some “other” type of SRA method. Benefits and Challenges The next several questions in the survey focused on collecting open-ended responses regarding the benefits and challenges of an agency’s chosen SRA methods. These open-ended responses were post-coded, and the results are presented in Figure 19 (benefits) and Figure 20 (challenges). 1,129 454 928 233 Figure 17. Safety Risk Assessment method used.

Survey Results 25   Figure 18. How Safety Risk Assessment method is used. Figure 19. Safety Risk Assessment method benefits.

26 Transit Safety Risk Assessment Methodologies Agencies that use the MIL-STD-882 tout this method as being “uniform, well-defined and organized” in addition to being “widely accepted.” Agencies that use the modified MIL-STD-882 state that this method “provides a more customized assessment of risk” (perhaps relative to its parent process) and, as such, “is more easily understood” (again, perhaps relative to its parent process). Because not many organizations that have in place some type of SRA method reported using the European CSM, the sample size is quite small. However, agencies that do use this method state that it “incorporates change management” well, is “more in line with regulatory requirements,” is “more easily understood,” is “uniform, well-defined and organized,” and “provides a more customized assessment of risk.” Agencies using some other method reported benefits similar to those reported for the modified MIL-STD-882. Agencies that use the MIL-STD-882 stated this method could be challenging because it is “highly subjective,” “confusing,” and, to a lesser degree, “lacks flexibility.” Agencies that use the modified MIL-STD-882 state that this method is also “confusing.” Additionally, it can be “resource intensive.” Being “resource intensive” held true for the European CSM and “other” methods, with the latter also being characterized by a “lack of familiarity.” When asked what specialized staff training, resources, or consultant support is needed to assist with the agency’s risk assessment approach or approaches, approximately half of the agencies Figure 20. Safety Risk Assessment method challenges.

Survey Results 27   reported that they relied on internal program training. As seen in Figure 21, internal training was the most common resource reported, followed by consultants, then federal program training. Resources and Satisfaction Last, agencies reporting use of some type of SRA were asked if they had considered changing their chosen methodologies. Roughly half of these agencies (22) said no, 15 said yes, and two said they were unsure. Table 2 presents some characteristics of the agencies based on their considerations. Relative to the agencies not considering a transition, agencies that are consid- ering a transition tend to offer fewer services to the public via a contractor, have a larger number of VOMS, are less likely to currently use the MIL-STD-882, and are more likely to currently use the European CSM. Characteristic Has Considered Changing SRA Method Has Not Considered Changing SRA Method Mean modes offered 2.93 2.82 Mean modes contracted 0.77 1.33 Total VOMS 956 617 Percent using MIL- STD-882 43 57 Percent using MMIL- STD-882 50 50 Percent using CSM 67 33 Percent using other method 46 54 Table 2. Characteristics of agencies considering and not considering changes to SRA methods. Figure 21. Resources used to support Safety Risk Assessment methods.

28 Transit Safety Risk Assessment Methodologies Discussion The organizations that participated in the survey represent a broad spectrum of transit agen- cies with regard to geographic distribution, size, modes offered, and utilization of contract providers. While most agencies used a single SRA methodology, a small proportion (approxi- mately 13 percent) use multiple methodologies. Nearly seven of 10 agencies (69 percent) use either MIL-STD-882 or a slightly modified version. The most common modification differen- tiating the former from the latter is an adjustment to the number of levels of either frequency/ probability or severity/consequences. The European CSM is the least often used method. Three agencies reported using the CSM, and two of those agencies use the CSM in conjunction with the modified MIL-STD-882. All three of these agencies agreed to participate as a case example (Chapter 4). Transit organizations reported using SRA most frequently on the following processes: • On hazards and other safety concerns that are identified through inspections and internal audits. • On hazards and other safety concerns reported by employees and/or riders. • When investigating a safety event, accident, or incident. Nearly all organizations have a level of risk that is deemed “acceptable.” However, the struc- tured interviews suggest that this level is not well defined, nor is it consistent across agencies. Rather, it is more important to agencies to be aware of the potential risks and to have strategies in place to mitigate harmful effects, if needed. The MIL-STD-882 is the most frequently used SRA method. Survey responses suggest its popularity may be a derivative of its uniformity, or that it is well defined, organized, and widely accepted across the industry. However, many survey respondents also felt that the MIL-STD-882 was confusing, particularly for transit staff not well versed on safety or the SRA. Furthermore, the process of assigning probability/frequency and severity/consequences is highly subjective and is often correlated with a person’s transit industry experience. Similarly, the modified MIL-STD-882 can be confusing as well as resource intensive. The modified MIL-STD-882’s primary benefit is that it allows for a higher degree of customization than its parent methodol- ogy. Last, some proponents of the European CSM suggest that it is more pragmatic, in line with regulatory requirements (particularly for Canadian organizations), and is beneficial because it incorporates change management (CM).

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Risk management is the central element of the safety management system (SMS). Identifying, assessing, analyzing, mitigating, communicating, and documenting are all steps in an effective risk management program.

The TRB Transit Cooperative Research Program's TCRP Synthesis 157: Transit Safety Risk Assessment Methodologies is designed to help the transit industry better understand current and new innovative state-of-the-practice methodologies in safety risk assessment (SRA), which is an important part of the system.

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