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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-95-176
Date: November 1996

Development of Human Factors Guidelines for Advanced Traveler Information Systems and Commercial Vehicle Operations: Task Analysis of ATIS/CVO Functions



Task E focuses on the analysis of the tasks that drivers and other operators of Advanced Traveler Information Systems (ATIS) and advanced information systems for Commercial Vehicle Operations (CVO) will perform when using these systems. The task analysis includes a recognition that ATIS/CVO tasks will often take place in conjunction with other, perhaps more urgent, tasks of controlling a vehicle and doing so safely. Understanding how drivers and other system operators will actually interact with and use ATIS/CVO systems under normal driving conditions is an important element of developing human factors design guidelines.

The task analysis performed was limited to relatively broad assumptions about the design specifications of specific systems. In some cases, particularly with the analysis of tasks involving In–Vehicle Routing and Navigation Systems (IRANS), and In–Vehicle Motorist Services Information Systems (IMSIS), the task analysis was based on prototype or first–generation equipment. In other cases, the analysis was based on system design specifications as they commonly appear in Intelligent Vehicle–Highway Systems (IVHS) plans and concept papers.

Information for the task analysis was gathered from a variety of sources. These included a review of information gathered in previous tasks in the ATIS project as well as by other researchers. It also included observations and interviews of drivers and dispatchers using prototype and first–generation operational systems. Since not all of the major functions associated with ATIS/CVO are represented by prototype systems, information was also gathered by having subjects describe how they would operate these systems if they were available.

Since this was the first real opportunity within the ATIS project to examine the influence of driving on ATIS/CVO functions, Task E devoted a good deal of attention to this issue. This was done by two methods: (1) the analysis included functions and tasks that primarily involved vehicle operation, and (2) each of the analyses was based on realistic driving scenarios.

The primary work of a task analysis involves organizing the things people and systems do into a usable format that allows the analyst to identify various conditions or characteristics that are important. Task E used three methods to accomplish this organization. The first was to organize information from a specific scenario into a graphical representation of the interactions that take place between both driving and ATIS/CVO functions. The second was to organize the tasks required to successfully complete a specific scenario into a graphical representation (i.e., an Operational Sequence Diagram [OSD]) that will show the sequence of task actions, the types of tasks involved, and the relationship between various human and non–human parts of the system. The last method used to organize the information was to describe each task in terms of its purpose, initiating conditions, task type, and performance considerations. This task characterization was done in a table format. Each analysis is described in detail in appendix D.

There are many different ways to perform a task analysis (see appendix A for summaries of papers proposing potential methods). The systematic approaches used in Task E represent some of the most commonly used conservative techniques. The use of standard OSDs and tables that describe task characteristics ensures a more general understanding of the information. It has the further advantage of providing a commonly accepted foundation for more detailed expansion of the task analysis as systems are developed. More sophisticated advanced network techniques are described in appendix B.

To provide information of greater potential and general use than is possible from the detailed task analysis, the report contains a composite analysis of the four main types of tasks. These include:

  • Tasks that are used to set up an ATIS function.
  • Tasks that serve as bridges between two or more ATIS functions.
  • Tasks that involve decision making by the driver or dispatcher.
  • Tasks that are integrated with critical driving tasks.

Each of these types of tasks were then examined in terms of the general characteristics of each task type and the task performance considerations that are common to that type of task. Results of the composite analysis were used to develop recommendations concerning the development of human factors design guidelines that will reflect both task requirements and human limitations. Areas were identified where additional research needs to be done before effective guidelines can be developed.

While the main body of the text provides a general summary and compilation of recommendations and conclusions, the report includes several appendices that document the supporting details of these conclusions. In addition, these appendices form a useful reference that future tasks can draw upon. Specifically, appendix A includes summaries of several papers that discuss previous task analyses of driving, general task analysis methods, and issues that a task analysis should address. Appendix B contains the details of an analysis of information flows among functional characteristics of ATIS/CVO systems. To analyze the relationships between functional characteristics, a number of social network analyses and graphical theory techniques were adopted. This analysis examines the relative centrality of each functional characteristic and shows which functional characteristics fall into tightly coupled groupings (which groups of functional characteristics share information). This analysis helped identify ATIS/CVO functional characteristics that should be included in the driving scenarios used for the detailed task analysis (appendix D). Appendix C contains a comprehensive hierarchical catalog of driving and ATIS tasks. This hierarchical task listing is shown in text lists and graphically as block diagrams. Appendix D examines these tasks in detail, using tables and diagrams to describe tasks listed in appendix C in the context of driving scenarios. Thus, the appendices form the foundation for the approaches and conclusions generated in the main body of the report.

In addition to the task analysis, this report also includes an integrated summary of the findings, observations, and issues that were identified as a result of work conducted in Tasks A through E. This summary appears as appendix E. The summary is organized around the following 11 research issues:

  • Issue 1. Existing status of research and development.

  • Issue 2. Formatting of information.

  • Issue 3. Driver capacity to assimilate information.

  • Issue 4. Knowledge, skills, and abilities requirements.

  • Issue 5. Information requirements of ATIS/CVO users.

  • Issue 6. Driver acceptance of ATIS/CVO systems.

  • Issue 7. Driver decision strategies for trip taking.

  • Issue 8. Factors influencing the performance of drivers.

  • Issue 9. Issues related to CVO system use.

  • Issue 10. Interactions between ATIS use and driving.

  • Issue 11. ATIS interactions.

Each research area is discussed in terms of combined findings and observations obtained from Tasks A through E. Following the summary, a list of recommendations for both human factors design guidelines and future research requirements is provided.




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