The task of navigating in unfamiliar road environments is a common and demanding cognitive activity for drivers. Research has long demonstrated the problems that drivers have in planning and following efficient routes to destinations. If efficient routes cannot be planned and followed, the consequences are stress, frustration and delays for the driver, potentially unsafe road behaviour (e.g. late lane changes) and inappropriate traffic management (e.g. traffic diversions through small villages). The usability of navigation systems is of paramount importance: they must be designed from a driver-centred perspective. The usability of a system refers to the "quality of interaction between a user and other parts of the system overall". Usability has been acknowledged as one of the most important aspects of navigation system design by several authors and has major implications for what information is presented to the driver by navigation systems, when, and in what format. Several authors have argued that navigation systems should be more naturalistic, i.e. their behaviour should approximate a passenger with detailed route knowledge providing navigation instructions to the driver as required. A key characteristic of more naturalistic navigation instructions is the inclusion of landmarks as navigation aids. The inclusion of landmarks within navigation instructions has the potential to: (1) enable navigation systems to more effectively aid navigation decisions; (2) reduce the cognitive effort and distraction imposed by these systems, and (3) result in systems which are more accepted by the driver. This paper addresses both the driver and industrial issues that must be tackled to enable inclusion of landmarks within navigation systems. Driver-centred issues are presented first, including the results of an empirical study to help identify the driver requirements for landmarks as a source of navigation information. The paper then discusses the industrial constraints and key barriers to the inclusion of landmarks within navigation systems. In conclusion, the implications for future navigation system development are discussed.
Abstract