John L Campbell

Development of human factors design guidelines for advanced traveler information systems (ATIS)

Past research has established that human factors guidelines following traditional formats for presenting information are not useful and are often ignored by designers. Within the human factors community, there is considerable uncertainty and concern regarding the nature and utility of human factors handbooks and guidelines materials. The objective of this paper is to describe and discuss three critical issues associated with the development of human factors design guidelines for advanced traveler information systems (ATIS). These three issues are: (1) the lack of human factors design criteria; (2) developing selection criteria for data sources used to produce guidelines; and (3) variability in the user population of human factors design guidelines. Within the context of these issues, some of the limitations, trade-offs, constraints, and options associated with the development of human factors design guidelines for ATIS are presented.

The development of human factors design guidelines

Abstract There is a growing information gap between the development of advanced human-machine systems, and the availability of human factors design criteria that can be applied during their design process. Despite increased interest in the development of human factors design guidelines, there also remains considerable uncertainty and concern regarding the actual utility of such information. Indeed, many existing human factors reference materials have been criticized by designers for being ‘too wordy’, ‘too general’, and ‘too hard to understand’. The development of clear, relevant, and useful human factors guidelines requires a judicious mix of science and art to overcome such criticisms. Specifically, while a number of empirical and systematic methods can be productively applied to their development, the final design guidelines will always represent a subjective integration of user requirements, design constraints, available information, and expert judgement. This paper summarizes procedures and heuristics associated with both the science and the art components of human factors design guideline development.

On-road versus simulator data in driver model development: Driver performance model experience

Driver Performance Model (DPM) development has provided results reflecting on the debate between on-road and driving-simulator data in driving research. Developed for FHWA, DPM is a computational micro-process model of driver behavior that has been designed to simulate—in detail—the driver’s perceptual, cognitive, and control processes to generate steering, braking, and acceleration inputs to the vehicle. The requirement to develop driver data for prediction of absolute on-road performance—versus typical interest in ordinal findings to be later validated via on-road studies—led to the collection of comparable on-road and simulator data and their subsequent comparison. Comparisons of corresponding curve-entry speeds and speed profiles revealed a profound divergence between the on-road and simulator results (t = 9.39, p < .005). Compared with simulator drivers, on-road drivers tended to have higher curve-entry speeds for the more difficult (sharper) curves and lower speeds for the less difficult curves. This trend, though reduced in magnitude, was apparent even after statistical adjustments for differences in respective tangent speeds (t = 2.67, p < .01). These results are discussed in light of emerging on-road and simulator capabilities. The discussion and earlier results altogether supported two conclusions: (a) debate concerning on-road versus simulator research studies is likely to continue with their rapidly emerging individual capabilities, and (b) on-road research currently provides the best basis for driver model development where one-to-one real-world predictions are required (e.g., DPM).

Comprehension testing of active safety symbols

This paper describes an effort to develop a valid and reliable process for comprehension testing of candidate automotive symbols and to conduct comprehension testing on a set of new symbols being considered for invehicle active safety systems. The comprehension testing process was developed though a multi-year effort, supported by Society of Automotive Engineering (SAE) and other organizations, aimed at generating a test methodology that would: yield high-quality comprehension data for new automotive symbols, provide clear and specific guidance back to symbol developers based on the test results, and could be adopted and performed internationally to support international standards efforts. Seventeen (17) candidate symbols were evaluated for three classes of in-vehicle active safety systems: forward collision warning (4 symbols), side collision warning (6 symbols), and lane departure warning (7 symbols). So far, testing has been completed in Germany, Sweden, Japan, and the United States. In the US testing, the study yielded comprehension data, appropriateness rankings, and diagnostic design feedback for all 17 icons tested. Based on these data, US recommendations have been made to the International Standards Organization (ISO) for all three classes of in-vehicle safety systems. This paper describes the process associated with developing the procedure, including the international outreach required to obtain support from major ISO countries, as well as the methods and results from the US testing.

Naturalistic Driving Study: Field Data Collection

This report describes the six Strategic Highway Research Program 2 (SHRP 2) naturalistic driving study (NDS) data collection centers and documents their data collection activities and strategies. The study centers were located in Bloomington, Indiana; State College, Pennsylvania; Buffalo, New York; Tampa, Florida; Durham, North Carolina; and Seattle, Washington. They collected data from more than 3,000 volunteer participants and their vehicles over a 3-year period. Information is provided on the recruitment and assessment of test participants, installation of NDS data acquisition systems into participant vehicles, management of the enrolled participants and their vehicles, retrieval of data from the vehicle fleet, and lessons learned. The report will be of interest to analysts wanting background on where and how the NDS data were collected and to researchers planning future large-scale NDS projects.

Driver Acceptance of General vs. Specific Icons for In-Vehicle Information

This study compared driver acceptance of general icons to specific icons for In-Vehicle Information System (IVIS) devices. In the study, general and paired specific icons, along with two unrelated icons, were tested in both the general and specific driving scenarios. Subjects were asked to select: (1) one icon that most accurately described the driving scenario; and (2) one or more icons that would be acceptable for the driving scenario. The most accurate icon type selected by the subjects was strongly associated with the given scenario type, with the exception of collision avoidance. That is, when the driving scenario was described in general terms, subjects typically selected general icons as most accurately representing the scenario; when the driving scenario was described in specific terms, subjects typically selected specific icons as most accurately representing the scenario. In contrast to the icon accuracy, high acceptance levels were obtained for both general and specific icons regardless of the driving scenario description. Therefore, general icons are capable of meeting driver expectations and preferences for a broad range of IVIS messages. Recommendations for icon design are: (1) general icons should be used as long as they do not negatively impact driver acceptance or driver performance; and (2) for safety-related messages, specific icons will provide higher levels of driver acceptance than general icons.

MODIFICATION AND PARTIAL VALIDATION OF THE DRIVER/VEHICLE MODULE

Four assumptions of the Driver/Vehicle Module of the Interactive Highway Safety Design Model were tested against data obtained in two on-road studies of driver behavior. Supported were assumptions that drivers track to the inside of horizontal curves and that a linear control model is adequate for describing steering behavior. Not supported were assumptions of consistent preferred lateral acceleration in horizontal curves and consistent preferred longitudinal accelerations and decelerations during curve approach and exit. Experimental results support (a) an analytically derived square-root relationship between preferred lateral acceleration and curvature and (b) an analytically derived square-root relationship between longitudinal acceleration or deceleration and total speed change.

Effective Ivis Icon Comprehension Research: Context and Response Scaling Methods

A refined approach used to determine the comprehension level of in-vehicle information system (IVIS) icons is introduced. This approach provides three primary improvements over classical evaluation procedures (e.g., ISO, 2001). First, this approach recommends the inclusion of context to ensure realistic comprehension scores. Second, the scaling method employed provides concrete, well-defined measurement criteria based on major and minor elements included in the icon message. Third, this approach allows the comprehension testing team to provide better diagnostic information back to the icon designers because it allows for analysis of what element(s) of the icon the subjects seemed to understand and what element(s) may have led to errors in comprehension. We recommend using this approach to provide high quality comprehension information for IVIS icon evaluations.

Human Factors Research Issues for the Integration of ITS Devices

This paper presents a summary of the activities and results of a human factors review for the Intelligent Vehicle Initiative (IVI) Program. Focus was on identifying human factors that need to be addressed early on in the life cycle of the IVI program. The project was conducted in two phases. The first phased involved a workshop which identified: state-of-the-art technologies applicable to IVI vehicles, human factors issues associated with each technology, and specific human factors research needs. The second phase of the project focused on a preliminary infrastructure and human factors in-vehicle requirements for alternative configurations of an IVI.

Validations of Integrated Driver Vehicle Interface (DVI) Configurations

This project examines questions of discernibility and presentation methods for safety-critical driving messages. A driving simulator experiment tested two methods of providing safety messages: distinct (with all alerts having distinct auditory and visual components) and master (a common visual and auditory alert) presentations. Participants completed drives that contained a safety critical event, with and without an alert, and reported their perceptions of the alert’s meaning and hazard location. No significant differences were observed in participants’ ability to identify the location of the referent hazard. There were significant differences in participants’ ability to assess the meaning of the alert: the distinct group displayed higher overall performance as compared to the master group. Implications of the study for design guidance and potential future research topics are discussed.