Protecting bridge maintenance workers: Evaluating fall protection supplementary devices using virtual prototyping and wearable technology

Apart from stuck-by safety incidents, fall-related injuries are a common concern among bridge maintenance and inspection workers. These workers, when performing on-the-deck operations, largely rely on existing bridge guardrails for their protection against falls to lower levels. Unfortunately, many of these bridge guardrails do not offer sufficient protection as required by safety regulations. More specifically, most bridge guardrails in the United States do not comply with the minimum barrier height requirement of 42 ± 3 inches for sufficient protection. As a result, bridge maintenance and inspection workers are often exposed to the risk of falls during bridge operations. Because making design alterations to all non-compliant bridge guardrails is currently not feasible, a few departments of transportation (DOTs) have begun adopting Fall Protection Supplementary Devices (FPSDs). These devices are temporarily placed over bridge guardrails to sufficiently increase the barrier height during bridge work. However, a critical challenge experienced by many DOTs is that a large number of manufactured FPSDs are not compatible or do not firmly attach onto every bridge guardrail – due to the design incompatibilities. Therefore, to ensure sufficient protection, workers are often required to test the compatibility of individual FPSDs before initiating work. This has traditionally been achieved through an inefficient trial-and-error based approach – where FPSDs are procured, transported to the bridge location, and physically tested for compatibility with guardrails. Unfortunately, if the FPSD is not compatible, alternate FPSD systems may not be immediately available to initiate work. More importantly, the traditional compatibility testing procedure unduly exposes workers to the risk of falls (i.e. , working alongside bridge guardrails that do not offer sufficient protection) and struck by safety incidents from vehicular traffic. Such challenges have discouraged several DOTs from adopting FPSDs in favor of less effective methods for bridge work. To encourage the adoption of FPSDs, the objective of this research were to (1) propose an efficient, effective, and safe approach to test the compatibility between FPSD systems and bridge guardrails; (2) identify FPSD systems that maximize work efficiency, productivity, and safety for bridge workers in North Carolina; and (3) conduct field-level usability studies comparing the recommended FPSDs against those that are traditionally adopted by the North Carolina Department of Transportation (NCDOT). The first objective was accomplished by adopting virtual prototyping to assess compatibility in a virtual setting. The proposed method is intended to replace the traditional trial-and-error based approach that has been inefficient, expensive, and unsafe. More specifically, the proposed method accurately replicates the physical testing procedure – but is conducted in a virtual environment – where the physical procurement, transportation, and testing of the FPSDs becomes unnecessary. The second objective was accomplished in three steps. First, compatible FPSDs were identified for the most common low-height bridge guardrails in North Carolina using the proposed approach. This effort yielded 11 FPSDs that are compatible with the 12 most common bridge guardrails in North Carolina. Second, by engaging NCDOT field workers, supervisors, and decision makers, desirable FPSD characteristics that can maximize safety, productivity, and work efficiency were identified. Third, the FPSDs that offered the most advantages were identified using the Choosing by Advantages (CBA) decision making method Finally, the third objective was accomplished by conducting field studies with bridge maintenance workers from NCDOT. To compare the recommended FPSDs against the FPSDs that NCDOT has used in the past, physiological, postural, productivity, and utility perception data from the workers were captured by means of wearable devices and survey questionnaires. The results indicated that the recommended FPSDs were perc ived as more utilitarian, required less physical demands, offered superior postural benefits, and increased operational efficiency and productivity. The study addresses a nationwide safety issue experienced by all transportation agencies and DOTs, while also facilitating the improvement of efficiency, productivity and other safety considerations during bridge maintenance and inspection operations.