Existing measures of road safety were primarily designed to evaluate motor vehicle crashes. Consequently, they are not well-suited for alternate or emerging modes of micromobile transportation, particularly the e-scooter, whose popularity has surged without a corresponding body of research on their safety. Effective safety analysis depends on complete, high-quality data capable of accounting for the relevant mode-specific dangers. The established criteria for measuring consequences and hazard exposure in risk metrics used for motor vehicles do not apply. Most road safety data sources and schemas have a similar motor vehicle-centric bias. This framing presents challenges when it comes to selecting and interpreting data about alternate modes of transportation like micromobility. This paper discusses a basic theory of risk metric selection and the purpose of transportation safety measures. It applies these ideas to the emerging mode of micromobility transportation and recommends appropriate criteria and limitations for each component of a metric. This paper also evaluates existing data sources and schemas to provide examples of bias and estimate the relative size of each issue. These considerations may serve as useful guidelines for further research in the area and help inform the requirements of data collection necessary to better answer questions of safety.
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