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HFG TUTORIALS Version 1.0 Tutorial 3: Detailed Task Analysis of Curve Driving A task analysis of the different activities that drivers must conduct while approaching and driving through a single curve (with no other traffic present) was conducted to provide qualita- tive information about the various perceptual, cognitive, and psychomotor elements of curve driving. Consistent with established procedures for conducting task analyses (Campbell and Spiker, 1992; Richard, Campbell, and Brown, 2006; McCormick, 1979; Schraagen, Chipman, and Shalin, 2000), the task analysis was developed using a top-down approach that successively decomposed driving activities into segments, tasks and subtasks. The approach used in this tutorial was specifically based on the one described in Richard, Campbell, and Brown (2006); readers interested in additional details about the methodology should consult that reference (available at http://www.tfhrc.gov/safety/pubs/06033/). The curve driving task was broken down into four primary segments, with each segment gen- erally representing a related set of driving actions (see Figure 22-8). The demarcation into seg- ments was primarily for convenience of analysis and presentation and does not imply that the curve driving task can be neatly carved up into discrete stages. Within each segment, the indi- vidual tasks that drivers should or must perform to safely navigate the curve were identified. Moreover, these driving tasks were further divided based on the information-processing ele- ments (perceptual, cognitive, and psychomotor requirements) necessary to adequately perform each task. The perceptual requirements typically refer to the visual information about the curve and the surrounding roadway that drivers need to judge the curvature, determine lane position and heading, etc. The cognitive requirements typically refer to the evaluations, decisions, and judgments that drivers have to make about the curve or the driving situation. The psychomo- tor requirements refer to the control actions (e.g., steering wheel movements, foot movements to press brake, etc.) that drivers must make to maintain vehicle control or to facilitate other information acquisition activities. The task analysis presented in Table 22-6 shows the driving tasks and corresponding information-processing subtasks associated with driving a typical horizontal curve, approach- ing from a long tangent. Drivers must also engage in other ongoing safety-related activities, such as scanning the environment for hazards; they may also engage in in-vehicle tasks such as adjust- ing the radio, using windshield wipers, or consulting a navigation system (just to name a few). However, these more generic tasks are not included in the task analysis in order to emphasize those tasks and subtasks that are directly related to curve driving. 1. Approach 2. Curve Discovery 3. Entry and Negotiation 4. Exit Tangent Point 75 -100 m (~4 sec) Point of Curvature Figure 22-8. The four primary segments of the curve driving task. 22-35
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HFG TUTORIALS Version 1.0 Table 22-6. Driving tasks and information-processing subtasks associated with a typical curve. Driving Task Perceptual Requirements Cognitive Requirements Psychomotor Requirements 1. Approach 1.1 Locate bend Inspect forward roadway Recognize visual cues Eye movements needed for scene for evidence of bend indicating departure from scanning straight path 1.2 Get available Visually scan environment Read and interpret sign Head and eye movements speed for signage information needed for scanning information from signage 1.3 Make initial Look at speedometer Read speedometer Execute necessary foot speed information and compare to movements to achieve adjustments posted speed desired speed change 2. Curve Discovery 2.1 Determine Look at roadway and Estimate curve angle based Head and eye movements curvature environment features at on visual image and needed for scanning curve location experience 2.2 Assess roadway Look at roadway in front Determine conditions Execute necessary foot conditions (e.g., of vehicle requiring (additional) speed movements to achieve low friction, reductions desired speed change poor visibility) 2.3 Make additional Look at speedometer Read speedometer and/or Execute necessary foot speed and/or view speed cues judge safe speed based on movements to achieve adjustments from environment cues and experience desired speed change 2.4 Adjust vehicle Look at roadway/lane Determine the amount of Head and eye movements path for curve marking information in the steering wheel displacement needed for viewing, and entry immediate forward view required to achieved desired precise arm movements for lane position steering control 3. Entry and Negotiation 3.1 Adjust speed Perceive lateral Judge safe speed based on Execute necessary foot based on acceleration and look at visual cues and experience or movements to achieve curvature/lateral roadway motion cues read speedometer desired speed change acceleration 3.2 Maintain proper Look at tangent point or Determine amount of steering Head and eye movements trajectory intended direction wheel displacement required needed for scanning, and to achieved desired heading precise arm movements for steering control 3.3 Maintain safe Look at roadway/lane Determine amount of steering Head and eye movements lane position marking information in the wheel displacement required needed for viewing, and immediate forward view to achieved desired lane precise arm movements for position steering control 4. Exit 4.1 Accelerate to Look at speedometer Read speedometer and/or Execute necessary foot appropriate and/or view speed cues judge safe speed based on movements to achieve speed from environment cues and experience desired speed change 4.2 Adjust lane Look several seconds Determine amount of steering Head and eye movements position ahead down the roadway wheel displacement required needed for scanning, and to achieved desired heading precise arm movements for steering control The primary source of information for segment tasks was the comprehensive driving task analysis conducted by McKnight and Adams (1970); however, other research more specifically related to curve driving were also used: · Donges, E. (1978). Two-level model of driver steering behavior. Human Factors, 20(6), 691707. · Fitzpatrick, K., Wooldridge, M. D., Tsimhoni, O., Collins, J. M., Green, P., Bauer, K. M., Parma, K. D., Koppa, R., Harwood, D. W., Anderson, I., Krammes, R. A., and Poggioli, B. (2000). Alternative Design Consistency Rating Methods for Two-Lane Rural Highways. Final Report. (FHWA-RD-99-172). McLean, VA: FHWA. 22-36
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HFG TUTORIALS Version 1.0 · Groeger, J. A. (2000). Understanding Driving: Applying Cognitive Psychology to a Complex Everyday Task. Hove, U.K.: Psychology Press. · Krammes, R. A., Brackett, R. Q., Shafer, M. A., Ottesen, J. L., Anderson, I. B., Fink, K. L., Collins, K. M., Pendleton, O. J., and Messer, C. J. (1995). Horizontal Alignment Design Con- sistency for Rural Two-Lane Highways. Final Report. (FHWA-RD-94-034). McLean, VA: FHWA. · McKnight, A. J., and Adams, B. B. (1970). Driver Education Task Analysis. Volume I. Task Description. (DOT HS 800 367). Washington, DC: National Highway Traffic Safety Administration. · Pendleton, O. J., and Messer, C. J. (1995). Horizontal Alignment Design Consistency for Rural Two-Lane Highways. Final Report. (FHWA-RD-94-034). McLean, VA: FHWA. · Richard, C. M., Campbell, J. L., and Brown, J. L. (2006). Task Analysis of Intersection Driving Scenarios: Information Processing Bottlenecks (FHWA-HRT-06-033). Washington, DC: FHWA. Available at http://www.tfhrc.gov/safety/pubs/06033/ · Salvendy, G. (Ed.). (1997) Handbook of Human Factors and Ergonomics (2nd ed.). New York: Wiley. · Serafin, C. (1994). Driver Eye Fixations on Rural Roads: Insight into Safe Driving Behavior. (UMTRI-94-21). Ann Arbor: University of Michigan Transportation Research Institute. · Underwood, G. (1998). Eye Guidance in Reading and Scene Perception. Oxford: Elsevier. · Vaniotou, M. (1991). The perception of bend configuration. Recherche Transports Securite, (7), 3948. For the most part, these references and the other research provided information about which tasks were involved in a given segment, but not complete information about the spe- cific information-processing subtasks. To determine this information, the details about the information-processing subtasks and any other necessary information were identified by the authors based on expert judgment and other more general sources of driving behavior and human factors research (e.g., Groegor, 2000; Salvendy, 1997; Underwood, 1998). 22-37