In-Service Performance Evaluation: Guidelines for the Assembly and Analysis of Data (2022) / Chapter Skim
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Pages 34-41
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From page 34... ...
34 The evaluation measures outlined in Chapter 4 assess in-service performance through consideration of • The structural adequacy of the SFUE; • The occupant risk, through consideration of the crash severity; and • The postimpact vehicle trajectory and impact orientation, through consideration of the crash sequence of events. Each of these evaluation measures capitalizes on the data already available within the jurisdiction.
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From page 35... ...
Assessing, Interpreting, and Implementing Results 35 evaluation measure, then further conditions are not considered until or unless an investigative ISPE is undertaken to obtain more cases or reduce the number of unknown values such that Condition 1 is met. Unknown or missing values in the data set are indicated with a value of 99 entered in a row for the crash corresponding to the field for which the value is unknown.
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From page 36... ...
36 In-Service Performance Evaluation: Guidelines for the Assembly and Analysis of Data situation, the variable PEN may be biased by unknown information due to the way the information was collected. Further, it is believed that this outcome will often not be noted even when it does occur because of the lack of this field on most state crash forms.
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From page 37... ...
Assessing, Interpreting, and Implementing Results 37 crash-ready hardware to provide a reasonable degree of assurance that the safety feature is in crash-ready condition (Table 9)
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From page 38... ...
38 In-Service Performance Evaluation: Guidelines for the Assembly and Analysis of Data A jurisdiction may wish to benchmark the performance of the safety feature, so that improvements can be tracked and quantified. If the SFUE has met or exceeded the PG established by the jurisdiction across the range of vehicles and posted speed limits it is exposed to, then the choices made regarding where and when to install the safety feature would appear to be appropriate.
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From page 39... ...
Assessing, Interpreting, and Implementing Results 39 • Safety features developed to meet MASH criteria or NCHRP Report 350 Test Level 2 include SPEED_LIMIT ≤ 45. • Safety features developed to meet MASH criteria or NCHRP Report 350 Test Levels 3–5 include SPEED_LIMIT ≤ 65.
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From page 40... ...
40 In-Service Performance Evaluation: Guidelines for the Assembly and Analysis of Data greater than 1 then breaching is shown to be a harmful outcome. Similarly, Evaluation Measure B examines whether a support structure breaks away in an impact (i.e., expected outcome)
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From page 41... ...
Assessing, Interpreting, and Implementing Results 41 limited to passenger vehicles in Section 5.2.2, then the analyst can conclude that non passenger vehicles may be experiencing a higher risk with the longitudinal barrier being evaluated. As with all analyses, each of the evaluation measures depends on the quality of the data used in the analysis.
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