USABILITY EVALUATION FOR INTELLIGENT TRANSPORTATION SYSTEMS
Jan H. Spyridakis Ann E. Miller University of Washington
Woodrow Barfield Virginia Polytechnic Institute and State University
To a large extent, the success of any information system, such as an Intelligent Transportation System (ITS), will depend on its usability or ability to be easily understood and conveniently employed by a user. Usability is a term with varied meanings, but it generally refers to the ease in which a system or its components can be used. For example, with an ITS, given an in-vehicle display, usability translates into how easy ITS decision making is about whether to take an alternative route, or a particular exit, or whether to delay a trip. The purpose of this chapter is to discuss how "usability analyses" can assist developers in designing ITS, formerly known as Intelligent Vehicle Highway Systems (IVHS). Drawing its theoretical base from human factors, cognitive psychology, technical communication, ethnography, and business, usability evaluation can help ensure a good match between the information provided by an ITS and users' information needs. Specifically, a usability analysis can help match the ITS capabilities to the users' needs, goals, and risk-taking comfort levels. Our basic premise is that for an ITS to be successfully employed and accepted by the public, its design must be based on principles of human factors. One of major themes of the human factors approach is to involve the user early in the design of the system. As shown below, usability analysis is a methodology that, if properly employed, will accomplish the goal of early user involvement in ITS design.
The relevance of usability analysis for ITS design is readily apparent when one considers some of the various components of an ITS. An ITS will consist