Safety, Volume 3, Issue 3 (September 2017) – 5 articles

The study results reported here are part of a larger research project that developed a manual for practitioners to improve safety at rail transit platform/train and platform/guideway interfaces. As part of that effort, passenger injury incident data was collected from five rail transit systems, and interviews were conducted with safety officers at other rail transit systems in the US and Canada. The data collected showed that stairs and escalators and general platform tripping produced more injury incidents than the platform/train and platform/guideway interfaces. Heavy rail transit with platforms that are higher than 24 inches from top of rail had more injury incidents than light rail transit that typically operates on low level platforms. Other causes of injury incidents included intoxication, attempted suicide, and distraction. Full article

Automation surprises in aviation continue to be a significant safety concern and the community’s search for effective strategies to mitigate them are ongoing. The literature has offered two fundamentally divergent directions, based on different ideas about the nature of cognition and collaboration with automation. In this paper, we report the results of a field study that empirically compared and contrasted two models of automation surprises: a normative individual-cognition model and a sensemaking model based on distributed cognition. Our data prove a good fit for the sense-making model. This finding is relevant for aviation safety, since our understanding of the cognitive processes that govern human interaction with automation drive what we need to do to reduce the frequency of automation-induced events. Full article

Although numerous research studies have investigated the effects of fatigue in commercial motor vehicle drivers, research with winter maintenance (WM) drivers is sparse. This study pilot-tested the feasibility of evaluating WM operator fatigue during winter emergencies using naturalistic driving data. Four WM operators participated in the study and drove two instrumented snow plows for three consecutive winter months. The operators also wore an actigraph device used to measure sleep quantity. As this was a pilot study, the results were limited and only provided an estimation of what may be found in a large-scale naturalistic driving study with WM operators. Results showed the majority of safety-critical events (SCEs) occurred during the night, and approximately half of the SCEs occurred when participants were between 5 and 8 h into their shifts. Fatigue was identified as the critical reason in 33% of the SCEs, and drivers were found to average less sleep during winter emergencies versus winter non-emergencies. However, one participant accounted for all fatigue-related SCEs. Although data were limited to two instrumented trucks and four drivers, results support the approach of using naturalistic driving data to assess fatigue in WM operators. Future on-road research is needed to understand the relationship between fatigue and crash risk in WM operators. Full article

Maintaining postural stability is crucial, especially in hazardous occupational environments. The purpose of the study was to assess the role of three occupational footwear (low top shoe (LT); tactical work boot (TB) and steel-toed work boot (WB)) on postural stability when exposed to an occupational workload (4-h) involving standing/walking using the sensory organization test (SOT) equilibrium (EQ) scores and comparing current results with previously published postural sway variables from the same study. Fourteen male adults were tested on three separate days wearing a randomized occupational footwear, at the beginning (pre) and every 30 min of the 4-h workload until 240th min. SOT EQ scores were analyzed using a 3 × 9 repeated measures analysis of variance at an alpha level of 0.05. Significant differences between footwear was found in eyes open (p = 0.03) and eyes closed (p = 0.001) conditions. Pairwise comparisons revealed that LT had significantly lower postural stability compared to TB and WB. No other significant differences were found between footwear and over time. Significant differences between footwear can be attributed to design characteristics of footwear. Lack of significant differences over time suggests that, even though the average EQ scores decreased during the workload implying less postural stability, SOT EQ scores alone may not be sufficient to detect postural stability changes over the 4-h workload. Full article

The underground mining industry, and some above ground operations, rely on the use of heavy equipment that articulates to navigate corners in the tight confines of the tunnels. Poor line of sight (LOS) has been identified as a problem for safe operation of this machinery. Proximity detection systems, such as a video system designed to provide a 360 degree view around the machine have been implemented to improve the available LOS for the operator. A four-camera system was modeled in a computer environment to assess LOS on a 3D cad model of a typical, articulated machine. When positioned without any articulation, the system is excellent at removing blind spots for a machine driving straight forward or backward in a straight tunnel. Further analysis reveals that when the machine articulates in a simulated corner section, some camera locations are no longer useful for improving LOS into the corner. In some cases, the operator has a superior view into the corner, when compared to the best available view from the camera. The work points to the need to integrate proximity detection systems at the design, build, and manufacture stage, and to consider proper policy and procedures that would address the gains and limits of the systems prior to implementation. Full article