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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-95-197
Date: December 1996

Development of Human Factors Guidelines for Advanced Traveler Information Systems and Commercial Vehicle Operations: Comparable Systems Analysis








Strengths and Constraints of the Comparable Systems Analysis

The analysis of comparable systems is a valuable approach for obtaining and organizing information about the successes and shortcomings of early attempts to design advanced systems for traveler information. The strength of the approach is that the lessons learned and the preliminary guidelines derived therefrom are based on systems that are directly relevant to ATIS/CVO systems. The weakness of the approach is that a limited number of specific systems (seven) were subjected to analysis. This represents a very small sample size from a hypothetical set of all possible ATIS/CVO–related systems that have been or could be developed. For example, not all of the ATIS/CVO subsystems (such as ISIS) were represented in the seven selected systems, and budget constraints prevented coverage of relevant systems in Europe and Japan. Therefore, the lessons learned and the guidelines presented here are not exhaustive. Other insights and lessons would have been learned if other systems had been covered.

The lessons learned and the guidelines presented must be considered not only non–exhaustive, but preliminary. They are based primarily on expert observation and interviews. Ultimately, they need to be subjected to empirical testing, corroboration, and refinement before being promulgated as design guidelines or specifications.


User–Centered Design With or Without Human Factors

Presumably, all people in the human factors profession acknowledge the need for user–centered design. One subtle lesson learned, or at least a reminder, from the present analysis is that the commercial forces that drive much innovation may invoke user–centered design without human factors input. At least two of the systems included in this analysis showed that an engineering design team may develop an advanced system, including the user interface, through strong communication with the user community, bypassing the skills and knowledge offered by human factors experts. Perhaps this reinforces the need for the human factors community to offer design guidelines to design engineers that are readily available and easy to use.





The comparable systems analysis indicated that there are some fundamental issues that need to be addressed to achieve the overall goals of efficiency and safety in surface transportation.


Driver Attention Management

When is a driver overloaded with information? How successful will drivers be in managing their attention and cognitive resources to deal with multiple tasks? One can conceive of clear cases of multi–task information overload, such as controlling the vehicle, monitoring traffic, talking on the phone, revising the destination on the ATIS, loading a new CD, monitoring the ATIS visual and auditory information, and so on. This is not a new issue, but it is a difficult one that has implications for safety as well as legal issues of liability. It is also rooted in the American spirit of independence and freedom of choice. Users are not likely to appreciate "lock–out" designs that only allow the driver to access functions under certain circumstances. Few drivers would accept a car stereo that allowed the channel to be changed only when the vehicle was in PARK or at zero speed. The same spirit is likely to pertain to ATIS/CVO functions. Commercial applications face similar issues. Should CVO system design lock out the driver from accessing functions while moving? An interim position, but certainly not a solution, is to make all features and functions available at all times, but to warn and instruct drivers not to use them unless stopped.

Research on driver information management is important for the design of ATIS/CVO systems. It also is relevant to Advanced Vehicle Control Systems (AVCS).


Use of ATIS/CVO Systems by Older Drivers

One of the issues identified in the comparable systems analysis was that the use of ATIS/CVO systems by older drivers is relatively unknown and needs further research. The aging population of the United States, the "baby boomers," will result in an increasing proportion of older drivers. No information or insights were obtained on this important issue from the current analysis and it remains a topic for further research.


The Measurement Problem

The measurement of driver performance is difficult because it is multi–variate and dependent on a flux of changing tasks. The measurement of driver attention, workload, and situation awareness is even more difficult because these are hypothetical constructs that cannot be measured directly. The challenges of empirical measurement of the effectiveness of advanced systems, such as ATIS/CVO systems, should not be underestimated. Without reliable and valid measures, the impact of these technologies on productivity and safety will be difficult to assess. The development of good measures is an important and challenging research issue.





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