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Federal Highway Administration Research and Technology
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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
COMPARABLE SYSTEM EMPIRICAL FINDINGS APPLICABLE TO ATIS/CVO
This section outlines several ATIS/CVO comparable systems. Comparable systems include display and control interfaces for military ground vehicles, ships, submarines, air-traffic control, nuclear and conventional power plants, rail vehicles, and aerospace crafts. Background information on each of these comparable systems will be provided. In addition, existing guidelines derived from the literature and their potential applicability to ATIS/CVO will be examined in the next section. Finally, research questions required to determine the ATIS/CVO applicability of these outlined comparable systems will be discussed in the Conclusions section of this report.
Nuclear Power Plant Systems
Within nuclear and conventional power plants, systems that could potentially have ATIS/CVO applications are in existence. O'Hara and Brown (1991) examined the problems and issues with nuclear power plant alarm systems–specifically, the human factors issues associated with the design. From this study, a number of recommendations and guidelines were outlined.
The proper application of advanced technologies to alarm systems, and an improvement in operator performance are recommended. Potential guidelines for using this with ATIS/CVO applications include the following:
These human factors–related recommendations work well with ATIS applications that require advanced display and alarm systems.
Richards, Gilmore, and Haney (1986) performed a case study of human factors guidelines on a user–computer interface design at EG&G National Engineering Laboratory. In a systematic approach to display integration, a number of areas requiring human factors input were outlined. These included workstation and equipment arrangement; the CRT display organization; the window system, menus, and information packaging; color coding; labeling; and text formatting. Some of these areas, depending on the ATIS/CVO system in question, may be relevant to ITS system design.
Literature is available that describes conventional and nuclear power workstation interfaces, and the guidelines involved in the design process. However, research that examines the effectiveness of the systems post–design is limited. Casey, Dick, and Allen (1984) conducted human factors and performance evaluations of the Emergency Response Information System (ERIS). This system is in place at a full–scale Boiling Water Reactor simulator. The ERIS was designed to support control room operators during emergency management situations, and specifically for "detecting abnormal operating conditions, assessing the safety status of the plant, executing corrective actions, and monitoring the plant response." Although the design seems to be beneficial to operators during emergency conditions, given the small subject size, it is difficult to make assumptions about the success of the ERIS design. A more thorough examination of the ERIS and similar workstations is required to determine the effectiveness of these designs. From this, the most effective design in terms of increased performance can be determined. Only when this work has been accomplished can the design guidelines used to develop the most successful workstations be noted and their applicability to ATIS/CVO (as well as other applications) be determined.
The armored ground vehicle is of potential value to ATIS/CVO applications, although there is little published research available. The task of driving an automobile is different than operating an armored vehicle in many respects. However, the two environments are quite similar when compared to other available comparable systems (e.g., aircraft). Ruisseau, Gorzerino, Moscato, and Papin (1988) noted that differences in armored vehicle environments included operators wearing specialized equipment, limited interior vehicle space, and the high level of nuisances including noise and vibration.
In addition to the differences in the operator's environment, the technology that must be employed in armored vehicles is quite specific. In addition to designing a control or visual system to meet the goals of these specialized tasks, the designs used in an armored vehicle must be able to withstand extreme temperatures, shock, and vibration, and must be undetectable to the enemy. Also, due to confined work spaces, designs must be comfortable to use and must have minimal controls.
Hudson (1986) outlined the specialized armored vehicle display technology involved in "night sight" devices and noted that a large field of view and good resolution are two prime design goals. To meet these goals, image intensifiers are required. Hudson described the technological development, including earlier designs that used "cascade" tubes and later designs that incorporated improved photocathode materials.
In terms of potential ATIS/CVO applications, the technology developed for the specialized task technology involved in armored vehicle operation should be considered. For ATIS/CVO applications that require night–vision displays, the technology outlined by Hudson (1986) may be relevant. Because tasks performed by automobile drivers and the armored vehicle operator are quite different, adapting armored vehicle technology to automobile technology must be done carefully. Depending on the desired ITS application, this specialized technology may require further consideration.
Aircraft Glass Cockpits
Within the glass cockpit literature there are several categories of systems. Each of these categories is summarized below. For an overview of glass cockpits, see the report by Jennings and Hannert (1987).
A well–examined topic in current research literature is HUD's (Deaton, Barnes, and Lindsey, 1989; Deaton, Barnes, Kern, and Wright, 1990; Ercoline and Gillingham, 1990; Naish and Miller, 1980; Sorkin, Kistler, and Elvers, 1989; Weinstein, Ercoline, and Bitton, 1992). Though the bulk of this literature deals with the development of HUD technology in aerospace environments (i.e., cockpits), there is a potential for ITS applications. Before applying these to automotive applications, it should be explored further.
Deaton et al., (1989) investigated pilot performance using windscreen bows as a type of HUD format. Different HUD formats were examined, including a "standard" format that used dotted lines at negative pitch attitudes, and an "enhanced" format that used sawtooth lines at negative pitch attitudes and horizon–pointing tails at the inner ends of the pitch lines. The results of a simulator study indicated that the "enhanced" format increased pilot performance, particularly at severe negative pitch altitudes.
In a study that examined the effects of HUD variations in airspeed and altitude display, Ercoline and Gillingham (1990) examined five different symbol set presentations. These included rotating pointers, rotating pointers with dots, moving vertical tapes, boxed digits, and trend bars. Results of a simulator study indicated that displays with less clutter increased pilot performance in terms of airspeed and altitude performance errors. Note that one of the purposes of this research was to provide data in order to add to the HUD symbology design standardization effort. This investigation, along with other similar empirical studies, examined areas of HUD symbology that could be incorporated into a set of design guidelines. If HUD technology is to be used in ITS, a similar type of standardization effort will be required.
Naish and Miller (1980) also examined and evaluated HUD formats. Three detectors were presented in HUD format. The displays were evaluated in terms of pilot performance in tracking, speed error, and workload. As in the Ercoline and Gillingham (1990) study, the results were developed into a set of design guidelines. Given the newness of HUD technology, it is essential that research of this nature be conducted. It is possible that many of the guidelines defined in these investigations may be applicable to the automotive environment. However, much research will need to be conducted to develop a new set of guidelines that takes into consideration the specific tasks of automotive driving.
Sorkin et al. (1989) investigated the usability of Auditory HUD's (AHUD's). AHUD's are defined as "systems that provide data about signals or events occurring at different spatial locations relative to the aircraft." The investigation examined the effectiveness of AHUD's in providing azimuth and elevation information. Results of the investigation suggested that a stereophonic display integrated properly with a head position sensing system may usefully improve an observer's information processing. This investigation illustrates that HUD technology is quite diverse and all of its applications have not yet been realized.
A relevant question regarding ITS research is, "Can HUD technology be adapted for use in ATIS/CVO applications?" Research needs to be conducted that examines the driving task in detail and outlines the incorporation of a HUD that would affect driver performance and safety. HUD technology has been shown to decrease pilots' response times (Deaton et al., 1989). If drivers' response or reaction times can be decreased without increasing the safety risks, HUD technology may be a good alternative. As illustrated in the aerospace study examples, the presentation of different HUD formats has been examined. In terms of an ATIS/CVO application, the type and format of displayed information should be explored in detail.
Airplane traffic information displays have been actively researched. There appears to be a problem with the orientation and vantage point of the traffic display view. Williams and Wickens (1991) and Aretz (1991) studied this by comparing north–up and track–up alignments in maps. Both experiments showed that optimum orientation is task–dependent. For navigation tasks requiring a track–up alignment (e.g., localization), an Ego–centered Reference Frame (ERF) was best; and for tasks requiring a north–up alignment (e.g., reconnaissance), a World–centered Reference Frame (WRF) was best. Williams and Wickens (1991) state that a north–up alignment does provide a stable alignment and could be used in situations where precise control is not critical.
Another orientation experiment was done comparing a map that employed the principle of visual momentum with the two traditional approaches–track–up and north–up (Aretz, 1991). A visual momentum display places a wedge in a map corresponding to a pilot's field of view. Results of this experiment indicate that a visual momentum display captures north–up alignment benefits in tasks that require an ERF.
Ellis, McGreevy, and Hitchcock (1987) studied the potential of using a perspective display instead of a plan view display (top down, two–dimensional). They concluded that the perspective display was preferred over a plan view display and it provided improvements in decision time and avoidance performance.
According to this research it appears that some type of perspective display with inherent track–up alignment would be best. However, the conditions inherent in an ITS/CVO application are somewhat different. Thus, the same benefits may not be realized by the addition of the third dimension in this application. If, in fact, perspective displays prove to be superior for ITS/CVO applications, then factors including the location of the computer eye, color coding, and the best vertical and horizontal scaling factors should be investigated. (See Green and Williams (1992) for a discussion of perspective display variations in vehicle applications.)
Reising and Hartsock (1989) studied the effectiveness of checklists and pictorial switch layouts (i.e., showing the location of a switch to be pressed) on a CRT screen. Results of this experiment indicate that pilots react to an emergency much quicker when the complete title of the emergency (versus just an abbreviated title) and the checklist are provided. Providing the pictorial display of switch layout, however did not provide any additional improvement in performance.
In other warning display research, an evaluation was made to find the effects of different symbol designs on search time and error rate (Blackwell and Cuomo, 1991). It was found that such factors as filling symbols, simplified shapes, and enhancing critical features decrease search times. This research contained some good design principles, but lacked any investigation of the meaning that is implied by different shapes and symbols.
Kelly (1983) studied the increments used to display a lead aircraft's speed (i.e., ground speed quantization). According to the study, 5.1–m/s (10 knots) supplied all of the information necessary for satisfactory performance, but performance dropped at the 10.3–m/s (20–knot) ground speed quantization level. However, pilots reported that their confidence in what the lead aircraft was doing increased when the lead aircraft's speed was displayed in smaller increments.
Mann (1987) performed an experiment augmenting forward visibility and autonomous landing guidance system concepts. The variables included:
This data is useful in defining the video and symbology dynamics required to reduce pilot disorientation and augment the low–visibility real–world visual scene.
Acceptance of technology
McClumpha, James, Green, and Belyavin (1991) studied automation acceptance by commercial airplane pilots who used high–technology cockpits in the United Kingdom. Results identified four factors reflecting pilot attitudes toward glass cockpits–understanding, workload, design, and skills. These may also be applicable toward ITS/CVO technology. In addition to these four factors, they found that increased hours on new technology were associated with less favorable attitudes toward the design. Young pilots reported that they were concerned with the possible loss of flying skills, while older pilots were less concerned with this.
Judge, Smith, and Beaudet (1991) described a pre–mission flight interface designed for fighter pilots. They reported that giving pilots the ability to tailor their individual system to their own personal preferences paid high dividends in pilot acceptance, trust, and human/electronics teamwork. Using this information in ITS/CVO design may present some safety and practicality problems. For example, can the general public, or even CVO operators, be trusted to use such freedom in an effective and responsible manner?
Aircraft Auditory Display Formats
Because of the visual demands that are sometimes placed on drivers, auditory display information may play an important role in ITS/CVO technology. One trend in cockpit displays is to use synthesized speech to present secondary information. In a comparison between speech and pictorial displays in a cockpit environment (Robinson and Eberts, 1987), it was found that pictorial displays with an omni–directional auditory cue were preferred. In a similar system, voice communication with the control tower was compared to the Data Link system. Data Link provides visual display communication information on a CRT screen. Results of this study indicate that the Data Link system reduced the strain on short–term memory, which in turn, reduced operational errors.
This research suggests that because of the limitations of short–term memory, pictorial/CRT displays of information may be preferred over auditory–speech displays in some circumstances. However, in ITS/CVO applications, the limitations on short–term memory may be less important than increasing the visual demands of the driver. This design trade–off should be further investigated.
Collision avoidance system
A ship collision avoidance system, that facilitates threat assessment and provides some indication of avoidance maneuvers (i.e., does not prevent maneuvers) was compared to visual lookout and conventional radar (CAORF Research Staff, 1978). In high-traffic conditions, performance degraded and became erratic when using visual and radar systems. The aiding component of the collision avoidance system was effective in making the maneuvers more predictable. This same result may occur in ITS/CVO applications. However, environmental differences must be recognized when making this generalization.
Other research (Mestre, Cavollo, and Peruch, 1986) has focused on using perspective displays for navigation in shipping lanes (similar to those used in the aerospace industry) and a rate-of-turn indicator. Results of this research indicate that these displays are beneficial as navigation aids.
Caution is required when using this data in ITS/CVO applications since the dynamic nature of ships is different from those of automobiles. For example, because of their great size, inertia, and slow speeds, ship control inputs have large time lags. As such, predictor and other informational displays make navigation tasks significantly easier.
Monitoring and guidance system
A paper by Breit (1981) described a system that provides information on vertical and lateral acceleration, hull stresses, and bow flare in ships. The system also demonstrated the best vehicle operator conditions to minimize damage to the ship's cargo. An interesting aspect of the system is that it allows the operator to pre-set the alert criteria. These values are then used in the prediction algorithm to determine the best maneuver in any given circumstance. This idea of having the operator input the pre-set criterion deserves further consideration. With this, there is potential to control for much of the variability that exists between individual drivers and within the environment. Research will be required to determine the parameters of variability between drivers and within the environment. It will also be important to investigate just how the driver should be allowed to manipulate an ITS/CVO system in order to account for this variance.