Navigation System Data Entry:
Estimation of Task Times

Paul Green

June, 1999

This report describes the literature used to develop SAE Recommended Practice J2365 and the resulting initial draft of J2365. SAE J2365 is being to developed to estimate task times and compliance with the 15-second maximum task time specified in SAE Recommended Practice J2364 (Navigation Function Access While Driving). A review of the human factors literature (Kurokawa's dissertation, Levison's Integrated Driver Model, the NASA MIDAS software, HOS and the Integrated Performance Modeling Environment) revealed that there was no existing software that was both readily available for PCs and provided automotive-specific examples. Acceptable alternative hand calculation methods were not found.

Therefore, the approach taken was to extend the Keystroke-Level Model in the GOMS family (popular in human-computer interaction) using data from automotive navigation studies for calibration. The resulting 11-step calculation procedure of J2365 begins with identifying all major goals (e.g., obtain guidance) and subgoals for each task the user performs along with identifying the method used (e.g., the street address method without short cuts). The analyst then describes exactly how each step of the process is carried out using pseudo code. Next, the analyst determines the associated elemental tasks (reaching for a device, keying (cursor, letter, space, enter), mental activity, searching, etc.) and their associated times. Those times are adjusted for driver age, and entered into a spreadsheet where they are totaled. As a final step, times are checked for reasonableness and the task sequences are adjusted as needed.

Graphical Abstract (.pdf) | UMTRI-99-17 Full Report (.pdf)


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