Human factors aspects of navigation systems in support of intelligent speed adaptation (ISA) functionality

This paper reports a study of the performance of in-vehicle navigation devices to assess speed-related functionality and the provision of speed information to drivers. There are currently no standards or assessments protocols for navigation devices that are complete and that are directly relevant to the assessment of commercially available intelligent speed adaptation (ISA) devices. Human factors research is not conclusive about the best ways to convey speed limit information and speeding alerts to drivers, and a review of the literature indicated that there are some human- machine-interface methods that should be avoided in the driving task. Protocols for the assessment of navigation devices should avoid being design restrictive, but should discourage poor interface design concerning speed limit information and speeding alerts to drivers. A protocol was developed to evaluate in-vehicle navigation devices offering an ISA capability. The intended outcome from the use of this protocol is to assist consumers in decisions to purchase these devices. Four ISA devices currently available on the Australian market were tested on-road in a scenario incorporating freeway, commercial and residential environments, similar to how the devices would be commonly used. The results indicated that the protocol was very robust, being repeatable, relevant and objective, and can be used as the basis for the development and promulgation of a standard for the assessment of the safety of in-vehicle navigation devices with an ISA capability.