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Publication Number: FHWA-RD-95-153
Date: November 1996
Development of Human Factors Guidelines for Advanced Traveler Information Systems and Commercial Vehicle Operations: Literature Review
CONCLUSIONS AND RECOMMENDATIONS
RESEARCH ISSUES, HYPOTHESES, AND EXPERIMENTS NEEDED FOR GUIDELINE DEVELOPMENT
ATIS/CVO research to date has been system description–oriented, with details of organization of research that is in process or needs to be conducted. There are many human factors research issues that need to be addressed before a comprehensive set of guidelines can be developed. However, as shown in this report, a number of issues have been resolved for ATIS systems and comparable systems and need not be re–addressed. It is apparent that as the development of hardware progresses, the next few years will see a marked growth in the literature available from both U.S. demonstration projects and foreign sources. Therefore, as the research planning phase of this project progresses, it is critical to continue reviewing current studies. Currently, the largest gap in findings is within Japanese research. Apparently, there is such a drive to get products to market in Japan that little human factors–type testing is done before products are released. This is not to say that the products are poorly designed, but the danger does exist of producing a product with a high workload demand. It is also possible that the information does exist, but that the publication of research findings stays within Japanese journals or never leaves the company whose system is being tested. Unlike the European system of development, the Japanese system is very competitive, and studies that could leak product information are withheld to maintain corporate secrecy.
In general, specific ATIS research is lacking for IVSAWS and ISIS applications. Although these ATIS systems generally do not have complex user interfaces, they present unique human factors and safety issues. IVSAWS is an alarm type of display; therefore, issues of timing, modality false alarms, and potential operator reactions must be addressed. Many ISIS issues are similar to IRANS and IMSIS; however, presentation of regulatory information carries with it critical issues of message reliability, priority, understanding, and interpretation.
In many ways, CVO research is leading the way for automotive ATIS applications. However, the types of CVO applications that are feasible and desirable are significantly broader in scope than automotive applications. Greater functionality can be provided for the driver because of demographics and greater opportunities for driving. However, issues of overload and driving intrusion are just as critical, if not more so.
Documents for human factors and safety research
There are two noteworthy reports guiding human factors and safety research. The first is the ITS report by Barb and Mast (1992), Safety and Human Factors Considerations, which is the product of a conference held at UMTRI in December 1990. The four working groups for ITS–Automatic Traffic Management Systems (ATMS), ATIS, Automatic Vehicle Control Systems (AVCS), and CVO–convened and formulated research recommendations.
The second major report is by Sheridan (1991) and is titled Human Factors of Driver–Vehicle Interaction in the IVHS Environment. This report does not contain focused information on CVO. However, ITS effects are dealt with in terms of human factors theory and models, such as human error, mental workload, cognitive models, control theory and dynamics, information processing, dynamic decision theory, and signal detection theory. The report also discusses experimental program needs for understanding and evaluating ITS safety.
Besides these two reports, the Transportation Research Board (TRB) has also produced relevant publications. A comprehensive inventory of 19 safety issues are categorized into 5 areas in the 1991 TRB circular #375, Strategic Highway Plan. Their framework consists of people, vehicles, highway environment, post–crash, and safety management. In TRB record #1318, Safety and Human Performance, Highway Systems, Human Performance, and Safety 1991, articles by Hitchcock (1991); Hungerford, Sperling, and Turrentine (1991); Khattak, Schofer, and Koppelman (1991); Taoka (1991); and Turrentine, Sperling, and Hungerford (1991) are presented. The four relevant article topics are:
Each of these sources should be used to develop research requirements. In addition to these findings, a number of research requirements were addressed in the other literature reviewed as part of this report. Also, the authors have identified gaps that were apparent from a lack of research activity. The above–mentioned research requirements are combined and described in the next section.
Specific research requirements
Research on in–vehicle guidance display systems is still needed to determine the effectiveness of different message lengths and wording, and icon effectiveness and salience. More research is also needed to determine the most effective voice–based guidance system. Several factors to be investigated include synthesized versus natural speech, voice in combination with text, and the style in which information is presented.
Advisory system display characteristics require further investigation. Optimal character size and screen density need to be determined for older and younger drivers. Standard icons that most effectively present information to drivers of all age groups need to be developed. Further research on vertical disparity should be performed to determine its effect on reaction time.
Zwahlen et al., (1987) suggested that the use of touch–panel controls in automobiles should be reconsidered and delayed. More research dealing with driver information acquisition, information processing, eye–hand–finger coordination and touch accuracy, control actions, and safety aspects needs to be conducted, and the designs and applications need to be improved to allow safe operation during driving.
Research is needed to determine the effectiveness of advisory systems in identifying drunk drivers and deterring them from driving. Effective warning systems are needed to advise alcohol–impaired drivers of potential hazards. Engineering adaptations, such as the use of protected left–turn signals, need to be investigated to help determine if they will prevent accidents caused by alcohol–impaired drivers.
In general, further research is needed to investigate the information needs of drivers. The needs of urban, rural, local, and visiting drivers must be determined. The amount of information available to drivers upon request and the amount provided to drivers normally must be determined. Research is also needed to determine how much information should be provided to drivers in the case of incidents and alternate route selections.
Barrow (1990) made three research recommendations:
Barb and Mast (1992) made the following recommendations for research on six areas of "Plain Old Driving" (POD):
In order to define driver needs, research and development are needed as described below (Barb and Mast, 1992):
The following items are needed to improve tools for data collection (Barb and Mast, 1992):
Various data bases need significant improvements (Barb and Mast, 1992):
Sheridan (1991) proposed the following specific ATIS–related experiments:
Gould (1989) makes the following observations.
As researchers await technological breakthroughs, there is a need to focus on the mode by which people structure or allocate space and on how they later recall and use that information. This will be key to designing optimal vehicle navigation systems. Individual cognitive differences also need to be considered. Stasz and Thorndyke (1980) found that the best predictor of their definition of map learning was the Building Memory Test from the Educational Testing Service. The test uses building position recall from a street map. Sholl and Egeth (1980) found that map reading and map learning have separate cognitive bases and that general mathematical and verbal abilities were strong predictors of map reading ability.
Sadalla and Hauser (1991) make the following research recommendations:
Marans (1990) made the following recommendations regarding user acceptance, in which three research areas were identified. The University of Michigan is planning the following:
Boyce (1988) posed the following research questions:
Burgett (1991) described some of the safety hypotheses associated with the TravTek system:
CVO–specific research requirements
Given that the average commercial driver is likely to be quite different than the average automobile driver in terms of demographic characteristics such as size, age, sex, and health, and performance characteristics such as information processing and response abilities in a multi–channel information system, it is critical to examine driver characteristics in the context of CVO (IVHS America, 1992a).
It is important to considers human factors when developing CVO technologies. Areas that need to be studied are:
Researchers must identify the information needed by the driver, vehicle, and control agencies (e.g., ATMS, fleet managers) and then identify the best means of presenting that information to users (Boehm–Davis and Mast, 1992).
Barb and Mast (1992) described several CVO research needs and questions that need to be addressed:
Summary of Knowledge Gaps Key to the Development of Human Factors ATIS/CVO Guidelines
ATIS/CVO research to date has been system description–oriented, with details of the organization of research that is being conducted or needs to be conducted. There are many human factors research issues that still need to be addressed before a comprehensive set of guidelines can be developed. However, as shown in this report, a number of issues have been resolved for ATIS or comparable systems and need not be re–addressed. As the development of hardware progresses, the next few years will see a marked growth in the literature available from both U.S. demonstration projects and foreign sources. Therefore, as the research planning phase of this project progresses, it will be critical to continue reviewing current studies.
The ITS literature produced to date aids in the development of the initial phase of ITS. However, because there is a lack of empirical data, the development of comprehensive guidelines is that much more dependent on analysis, modeling, and empirical research.
It is anticipated that the data from initial U.S. operational tests and additional European and Japanese projects will fill some of the gaps in the human factors knowledge base. TravTek, as previously described, has a number of IRANS and IMSIS features and will provide data from numerous studies with well over 1.6 million km (1 million mi) of data collected. The University of Michigan Transportation Research Institute's (UMTRI's) project also will provide data, as well as preliminary models that may help in the establishment of guidelines. The ADVANCE and Guidestar projects promise data from even larger groups of users in the near future.
In order to develop comprehensive and general guidelines that are useful for years to come, models of driver performance while using ATIS and CVO systems must be developed. This research will likely include application and/or modification of existing models (e.g., UMTRI or model driver processing proposed by Sheridan, 1991, or Kantowitz, 1990), as well as creation of new models or model parameters associated with ATIS/CVO–specific applications.
In general, ATIS research is lacking IVSAWS and ISIS applications. Although these ATIS systems probably will not have complex user interfaces, they present unique human factors and safety issues. IVSAWS will be an alarm display; therefore, issues of timing, modality false alarms, and potential operator reactions must be addressed. Many ISIS issues are similar to IRANS and IMSIS; however, presentation of regulatory information carries with it critical issues of message reliability, priority, understanding, and interpretation.
In many ways, CVO research is leading the way for automotive ATIS applications. However, the types of CVO applications that are feasible and desirable are significantly broader in scope than automotive applications. Due to differences in driver demographics and greater opportunities for training, greater functionality can be provided for the CVO driver. However, issues of overload and driving intrusion are just as critical, if not more so, for CVO applications when compared to automotive applications. In addition, system design alternatives that would be unacceptable for automobile drivers due to cost and/or acceptability/marketing constraints may be acceptable for certain CVO applications. Therefore, a number of CVO–specific empirical projects must be undertaken to establish guidelines for the broad scope of useful CVO functions.
In general, further research needs to be performed to investigate the information needs of both automobile and CVO drivers. The information needed only by urban, rural, local, and visiting drivers must be determined. The amount of information available to the driver upon request and the amount provided to the driver normally must be determined. Researchers also need to determine how much information should be provided to the driver in the case of incidents and alternate route selections.
Driving capacity is a major research gap requiring both the application of existing guidelines and the creation of new guidelines. The human factors community is currently divided on the issue of what is safe and what is unsafe in the driving environment. The primary cause of this debate has centered around IRANS applications and will require additional research to resolve. In addition, many of the more difficult issues relating to resource capacity for trained CVO drivers and multi–function systems have not been addressed empirically or descriptively. Carefully planned and executed experiments that provide general principles instead of system–specific do's and don'ts are needed. In addition, an understanding of potential safety benefits and the costs of using ATIS/CVO are needed for guideline development. It is easy to dismiss a display that provides complex information as requiring too many driver resources. However, until (1) a comparison is made with current techniques for retrieving necessary information, and (2) an assessment is performed to determine the benefit of having the information, a proper assessment cannot be made.
Driver acceptance of ATIS and CVO technology also needs to be researched. Even a safe and efficient system design will not achieve the goals of ATIS and CVO systems if the needs and desires of the user are not met. Poor market penetration will result. Although a number of surveys have been conducted and describe desirable ATIS and CVO features, ongoing research is necessary to establish the information and control requirements for system (and product) success. Once information requirements have been established, human factors design guidelines can be established.