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Locomotives produce vibrations and mechanical shocks from irregularities in the track, structural dynamics, the engines, the trucks, and train slack movement (Mansfield, 2005). The different directions of the irregularities give rise to car-body vibrations in multiple axes including the following: • longitudinal, or along the length of the train (x); • lateral, or the side-to-side direction of the train (y); • vertical (z). The structural dynamics of rail vehicles give rise to several resonances in the 0.5–20Hz frequency range (Andersson, et al., 2005). Resonances are frequencies in the locomotive that cause larger amplitude oscillations. At these frequencies, even small-amplitude input vibration can produce large output oscillations. Further exacerbating the vibration environment, coupling of the axes of movement occurs: Motions in one direction contribute to motion in a different direction. The magnitude of vertical vibration in rail vehicles is reportedly well below many other types of vehicles (Dupuis & Zerlett, 1986; Griffin, 1990; Johanning, 1998). However, a lack of data from long-haul freight operations prevents an adequate characterization of the vibration environment of locomotive cabs. The authors describe results from 2 long-haul whole-body vibration (WBV) studies collected on a 2009 GE ES44C4 locomotive and a 2008 EMD SD70ACe. These WBV studies sponsored by the Federal Railroad Administration (FRA) examined WBV and shock in locomotives over 123 hours and 2274 track miles. The researchers recorded vibration data using 2 triaxial accelerometers on the engineers’ seat: a seat pad accelerometer placed on the seat cushion and a frame accelerometer attached to the seat frame at the base. The research team collected and analyzed vibrations in accordance with ISO 2631-1 and ISO 2631-5. ISO 2631-1 defines methods for the measurement of periodic, random and transient WBV. The focus of ISO 2631-5 is to evaluate the exposure of a seated person to multiple mechanical shocks from seat pad measurements. Exposure to excessive vibration is associated with an increased occupational risk of fatigue-related musculoskeletal injury and disruption of the vestibular system. While this is not an established causal relationship, it is possible that vibration approaching the ISO 2631-1 health caution guidance zones may lead to an increased occupational risk. The results from these rides show that the frequency-weighted ISO 2631 metrics are below the established health guidance caution zones of the WBV ISO 2631 standards. The goals of these studies are to: • collect data in accordance with international standards so results can be compared with similar findings in the literature for shorter duration rides as well as vibration studies in other transportation modes, • to characterize vibration and shock in a representative sample of locomotive operations to be able to generalize the results across the industry, and • collect benchmark data for future locomotive cab ride-quality standards.

This paper discusses the development of a user-centered control stand for the Federal Railroad Administration’s (FRA) Next Generation Locomotive Cab (NGLC) demonstration program. A “modified” Association of American Railroads (AAR) 105 side-mounted control stand was used as a starting point to facilitate bidirectional locomotive operation. Researchers applied a variety of qualitative human factor methods, including literature review, naturalistic observation, computer modeling, and heuristic evaluation, to design the improved control stand. The final design included a decluttered side control stand, a short desktop with three-panel front touchscreen displays that can accommodate and integrate current and future locomotive train technologies, and an overhead ceiling panel that replaces, in part, controls and displays traditionally located behind the engineer on the back wall. A mockup of the revised control stand design was fabricated as part of this program to demonstrate the human factors and ergonomic improvements. Researchers conducted structured interviews with locomotive engineers to validate the user-centered design approach. The engineers engaged in interactive scenarios that assessed the functionality of the workspace. The usability results provided the opportunity to improve upon the initial NGLC user-centered design. Changes included minor relocation of controls because they were in the reach path of other controls. Certain frequently accessed controls required relocation to more accessible locations. The LCD displays were redesigned with respect to information groupings and visibility issues. Feedback revealed that the transition from mechanical operations to electronic operations will result in the loss of auditory cues inherent in mechanical operations. The researchers suggest simulating auditory cues to promote personnel transition from mechanical to electronic operations. The results of this usability assessment identify the opportunity for future R&D cab integration efforts and demonstrate the importance of user-centered design and usability assessment in these efforts.

Locomotives produce vibrations and mechanical shocks from irregularities in the track, structural dynamics, the engines, the trucks, and train slack movement (Mansfield, 2005). The different directions of the irregularities give rise to car-body vibrations in multiple axes including the following: • Longitudinal, or along the length of the train (x); • Lateral, or the side-to-side direction of the train (y); • Vertical (z). Some reports suggest that acceleration at the seat pan is greater than that at the floor, indicating that the seat may amplify the vibration (Johanning, et al., 2006; Mansfield, 2005; Oborne & Clarke, 1974; Transport, 1980). The magnitude of vertical vibration in rail vehicles is reportedly well below many other types of vehicles (Dupuis & Zerlett, 1986; Griffin, 1990; Johanning, 1998). However, some research reports that rail vehicles experience far more lateral vibratory motion than cars and trucks (Lundstrom & Lindberg, 1983). Many factors influence the impact of shock felt by the engineer including train speed, consist, engineer control skills, anticipation of the shock, motion amplitude, shock duration, and body posture. Shock events and vibration affect ride quality; however, shocks are less controllable by locomotive design. Common sources of mechanical shock are coupling and slack run-ins and run-outs (Multer, et al., 1998). While there are investigations of whole-body vibration (WBV) in locomotive cabs reported in the literature, there have been no studies to date that have examined long-haul continuous vibrations (> 16 hr). The authors describe a long-haul WBV study collected on a 2007 GE ES44DC locomotive. It is the first in a series of studies sponsored by the Federal Railroad Administration (FRA) to examine WBV and shock in locomotive cabs. The researchers recorded vibration data using 2 triaxial accelerometers on the engineers’ seat: a seat pad accelerometer placed on the seat cushion and a frame accelerometer attached to the seat frame at the base. Data collection occurred over 550 track miles for 16hr 44min. ISO 2631-1 defines methods for the measurement of periodic, random and transient WBV. The focus of ISO 2631-5 is to evaluate the exposure of a seated person to multiple mechanical shocks from seat pad measurements. The research team collected and analyzed vibrations in accordance with ISO 2631-1 and ISO 2631-5. The results from the study as well as future planned long-haul studies will provide a benchmark set of WBV metrics that define the vibration environment of present-day locomotive operations.

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