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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

 

Findings From the TravTek Design Methodology

 

The TravTek design process was an iterative blend of design and testing that is depicted in figure 41 (Fleischman et al., 1991). The process itself provides lessons learned about the design of an ATIS system. Some of these lessons are summarized below:

The use of a team of human factors and systems engineering experts throughout the design process facilitates design. The TravTek interface was quite complex, and often required that design be constrained by driver, vehicle, and cost factors. As such, there were many design changes and iterations that required close scrutiny. Each member of the team (three human factors experts on a part–time, but ongoing basis; a linguistics expert; and two systems engineers) made significant contributions throughout this process.

The use of "standard" human factors design techniques was critical. These included task analysis, function allocation, and somewhat informal trade–study analyses.

Laboratory usability testing early in the system design process that used rapid prototyping and testing in a dual–task environment was helpful. Design decisions generated or supported by this process included conservative use of "moving maps" (i.e., only when necessary, as a secondary choice to turn–by–turn guidance screens, and in conjunction with voice guidance).

Testing of labeling and nomenclature used in the system proved to be very valuable. TravTek was essentially a computer interface for the computer illiterate. Effective nomenclature proved to be somewhat critical for navigation within the menu system and for understanding of the functions. It is very difficult for even an experienced human factors designer to anticipate or analyze the optimum use of labeling and nomenclature.

Users, in general, can adapt behavior in a driving dual–task environment and drive safely. This is not to say that a driver has unlimited resources to effectively use a poorly designed system; however, drivers seem to be able to utilize ATIS systems such as TravTek at least as effectively and safely as existing means (e.g., paper maps) for performing the same functions.

Despite the above statement, there is insufficient driving research available to accurately predict and model driving performance using an ATIS system without significant user interface testing. Thus, conservative loading of the driver is still warranted. Conservative features of the TravTek system that led to system success included: no access to touchscreen functions while the vehicle was in motion, the use of a guidance screen instead of a moving map as the primary guidance display, and the supplementary use of voice in conjunction with the visual display.

Even with the most carefully designed interface, some opportunity for orientation and training is necessary and very useful. For TravTek, a video and demonstration procedure was utilized that took approximately 30 minutes.

 

Questionnaire rating of the guidance screen traffic condition/incidence information

 

Questionnaire rating of the TravTek main menu

 

Questionnaire rating of the TravTek on-screen keyboard

 

Questionnaire rating of the TravTek steering wheel buttons

 

Questionnaire rating of the TravTek help feature

 

Questionnaire rating of the TravTek help desk

 

TravTek design process

 

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