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Publication Number: FHWA-RD-98-057

Human Factors Design Guidelines for Advanced Traveler Information Systems (ATIS)and Commercial Vehicle Operations (CVO)

 

CHAPTER 3: GENERAL GUIDELINES FOR ADVANCED TRAVELER INFORMATION SYSTEM (ATIS) DISPLAYS

 

SENSORY MODALITY FOR PRESENTING ATIS/CVO MESSAGES

Introduction: Sensory modality for presenting ATIS/CVO messages refers to the display modality most appropriate for presenting in-vehicle information to the driver. Almost all the literature on this topic suggests that operator performance can be improved by combining auditory and visual messages. These channels should be used together to provide either redundant or complimentary cues to the driver whenever possible. However, it is also important to know the advantages and disadvantages of using each of these modalities independent of one another, so that when designers are faced with a choice, they can choose the modality that facilitates driver decision making and performance.

Design Guidelines***

Information Characteristic

Sensory Modality

High Complexity

Visual

Low Complexity

Auditory

High Priority

Auditory

Low Priority

Visual

Intermittent Display

Auditory

Continuous Display

Visual

Requested Presentation

Auditory (Unless complex, then visual)

Automatic Presentation

Visual (Unless high priority, then auditory)

 

Heuristics for Assessing Complexity and Priority

Complexity is a function of how much information is being provided and how difficult it is to process. The phrase "information units" is used to describe the amount of information presented, in terms of key nouns and adjectives contained within a message. The design guideline entitled "Auditory Message Length" on page 3–26 provides a tool for determining the number of information units.

High Complexity

Low Complexity

> 9 information units

3-5 information units

Processing time > 5 s

Processing time < 5 s

Examples: topographical representations of a route, or full route maps, or schedules for alternate modes of transportation

Examples: directions of turns, or estimates of travel costs

Priority is a function of the urgency of a response and the consequences of failing to make a response.

High Priority

Low Priority

Fast response needed (0–5 minutes)

No response needed (5 min +)

Serious consequences (death or injury)

No immediate consequences

Examples: notification of serious traffic conditions which may affect the safety of the driver, or mechanical problems which could impact the safety of the driver or the condition of the vehicle

Examples: vehicle maintenance schedules, or weather information

Supporting Rationale: Reference 1 found that drivers can process complex information faster through the visual channel than through the auditory channel, especially when pictures can be used instead of words. When presenting information aurally, an attempt should be made to make it simple so that it does not exceed the capabilities of working memoryC7 to 9 information units (see also Reference 2).

Information to be presented continuously is best presented visually so that it does not become a nuisance to the driver. Continuous auditory information could very well be perceived as chattering and nagging, or could overwhelm the driver with too much information. On the other hand, information presented intermittently is best presented aurally so that the driver is made aware of its presentation.

According to Reference 3, when information is requested, it should be presented through the modality that is most appropriate for its complexity so that the driver can most easily understand and utilize the information. However, when information is presented automatically to the driver, the information should be presented visually unless it is of an urgent nature. In cases such as this, the information should be presented aurally so that it is sure to capture the attention of the driver regardless of where the driver is looking.

Similarly, information that is considered high priority or that requires a very quick response from the driver should be presented through the modality which commands the drivers attention the fastestCthe auditory mode. Any other information that can be considered advisory or purely informative (without being requested) can best be presented in the visual mode, which will not distract the driver from the main task of driving.

Special Design Considerations: Reference 3 suggests that these are general guidelines to be followed. However, each information element should be considered individually in order to ensure the most appropriate sensory modality for presentation. Another very important issue to consider is whether or not the driver needs the information while the vehicle is in–transit, or if receiving the information predrive would be sufficient. Knowing this could cause the designer to come to a very different conclusion regarding the most appropriate display modality.

In Reference 4, a driving simulator was used to study the benefits of multimodal displays (both auditory and visual). The multimodal displays were associated with better driving performance than auditory–only or visual–only displays, as well as better performance on a navigation task. Both the multimodal and auditory–only displays were associated with better emergency responses than the visual–only display.

Cross References:

Auditory Message Length

Complexity of ATIS Information

Modality of ATIS Information for CVO

Key References:

    1. Deatherage, B. H. (1972). Auditory and other sensory forms of information presentation. In H. Van Cott & R. Kinkade (Eds.), Human engineering guide to equipment design (Rev. ed.), (pp. 123–160). Washington, DC: U.S. Government Printing Office.

    2. Labiale, G. (1990). In–car road information: Comparison of auditory and visual presentation. Proceedings of the Human Factors and Ergonomics Society 34th Annual Meeting, (pp. 623–627). Santa Monica, CA: Human Factors and Ergonomics Society.

    3. Mollenhauer, M. A., Dingus, T. A., & Hulse, M. C. (1995). Recommendations for sensory mode selection for ATIS displays. Proceedings of the Institute of Transportation Engineers 65th Annual Meeting: A Compendium of Technical Papers. Washington, DC: Institute of Transportation Engineers.

    4. Liu, Y., & Dingus, T. A. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Human factors evaluation of the effectiveness of multi–modality displays in advanced traveler information systems. Washington, DC: Federal Highway Administration (FHWA–RD–150).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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AUDITORY MESSAGE LENGTH

Introduction: Auditory message length refers to the number of syllables, words, or sentences necessary for presenting auditory information to the driver. Depending on the type of information being presented, different message lengths are acceptable.

Design Guidelines***
  • Messages that require an urgent action should be a single word or a short sentence with the fewest number of syllables possible. Drivers should be able to understand the message immediately.

  • Messages that are not urgent or for which a response may be delayed can be a maximum of 7 units of information in the fewest number of words possible. If the information cannot be presented in a short sentence, the most important information should be presented at the beginning and/or the end of the message.

  • Navigation instructions should be limited to 3 or 4 information units.

 

Determining the Number of Information Units

4 units

Road Construction Ahead
atJaspertown

8 units

Road Construction onInterstate 5
for next 10 miles
Take Highway 99

11 units

Interstate 80 closed for construction
between Iowa City and Cedar Rapids
Exit at West Liberty
and drive north on Highway 16

16 units

Accident Ahead
Exit #215 closed to Dover
Traffic detoured to Exit #216
Follow Highway 46 to Chester
and turn east onto Inglenook Road

 

Examples of Auditory Messages

Suggested

Not Suggested

"Accident ahead, merge right."

"Accident ahead in the left lane, merge right as soon as possible."

"Oil change needed by July 1, 1997."

"Vehicle maintenance log shows that vehicle oil change is due and should be completed by July 1, 1997."

"Turn right in 2 miles."

"At the next stoplight, turn right onto Stark Lane in 2 mile."

 

Supporting Rationale: The longer the message, the more processing time required by the driver. Therefore, messages that require the driver to make an immediate response should be as short as possible. One–word messages informing the driver of the appropriate action to take might work best in situations such as these. As the response required by the driver becomes less and less urgent, the messages can become more detailed. However, an effort should still be made to make the messages as concise as possible.

Special Design Considerations: When presenting messages that do not require immediate action, Reference 1 suggests several things for helping the driver use the information: (1) Present the information in the order of importance or relevance to the driver; (2) Present the most important information at either the beginning or the end of the message because it is easiest to recall; (3) Highlight the most important parts of the message; (4) Provide a means for repeating the messageCthis is especially helpful for older drivers; and (5) Provide a redundant visual presentation of the informationCthis is also helpful for older drivers.

Cross References:

Sensory Modality for Presenting ATIS/CVO Messages

ATIS Design for Special Populations

Key References:

    1. Ross, T., Midtland, K., Fuchs, M., Pauzie, A., Engert, A., Duncan, B., Vaughan, G., Vernet, M., Peters, H., Burnett, G., & May, A. (1996). HARDIE design guidelines handbook: Human factors guidelines for information presentation by ATT systems (DRIVE II Project V2008).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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COMPLEXITY OF ATIS INFORMATION

Introduction: The complexity of ATIS information refers to the number of information units being presented during written or textual in–vehicle road messages. In this context, an information unit can describe geography (e.g., city), type of roadway (e.g., highway), event causes (e.g., stalled vehicle), event consequences (e.g., traffic jam), time and distances, and proposed actions. Therefore, information units can be described as the relevant words in a message.

Design Guidelines***
  • Text messages presented when the vehicle is in motion should be no longer than 4 information units, in order to minimize the eyes–off–road time.

  • Many text messages are best presented while the vehicle is stationary. In these cases, 6–8 information units are optimal.

 

Determining the Number of Information Units

4 units

Road Construction Ahead
atJaspertown

8 units

Road Construction onInterstate 5
for next 10 miles
Take Highway 99

11 units

Interstate 80 closed for construction
between Iowa City and Cedar Rapids
Exit at West Liberty
and drive north on Highway 16

16 units

Accident Ahead
Exit #215 closed to Dover
Traffic detoured to Exit #216
Follow Highway 46 to Chester
and turn east onto Inglenook Road

 

The Effects of Information Complexity (from Reference 2).

Length of Message

3–4 units

6–8 units

10–12 units

14–18 units

 

 

 

 

 

 

 

 

 

Duration of Glance

1.08 s

1.18 s

1.20 s

1.35 s

Number of Glances

3.8

6.9

9.6

15.5

Memory Recall

100%

97.5%

75.4%

52.4%

 

Supporting Rationale: Reference 1 analyzed the number of lane deviations that occurred while operating a CRT touch screen. The results suggest that the number of glances away from the roadway be limited to 3 and that glance durations which exceeded 2 seconds in duration are unacceptable. Reference 1 examined the amount/complexity of information necessary for evoking these unsafe glance frequencies and durations. The results of this on–road study suggest that although the duration of glances does not increase dramatically as the number of information units increase, the number of glances does. Therefore, the shortest information message (3–4 units) would be the most appropriate for keeping drivers' attention on the forward roadway. The driver's ability to recall information was also examined in Reference 2. Only 75 percent of a 10–12 unit message could be recalled, in comparison to 100 percent of a 3–4 unit message and 98 percent of a 6–8 unit message. This finding is consistent with Reference 3, which proposed that the maximum capacity of working memory is "seven, plus or minus two" chunks of information. Again, this finding suggests that keeping the message short, 3–8 information units, would increase the likelihood that it will be recalled by the driver.

Special Design Considerations: According to Reference 4, both glance durations and glance frequencies increase with age, due to the deterioration of vision and slowing of cognitive processes. Older people also experience many more problems associated with retention, as studies have shown that increasing the difficulty of memory–related tasks will affect the performance of older subjects more than younger subjects (see Reference 5). Therefore, making messages shorter and simpler will help to improve performance, particularly for older drivers. Reference 6 suggests increasing the display time of messages or providing a "repeat last message" function so that drivers could pace themselves. In this way, older drivers would be able to call up information at the rate that they are comfortable receiving it, thus reducing excessive glances to the screen.

Cross References:

Auditory Message Length

ATIS Design for Special Populations

Presentation of General Trip Planning Information

Presentation of Roadway Information

Presentation of Point of Interest Information

Presentation of Travel Coordination Information

Presentation of Route and Destination Selection Information

Presentation of Dynamic Route Selection Information

Key References:

    1. Zwhalen, H. T., Adams, C. C., Jr., & DeBald, D. P. (1988). Safety aspects of CRT touch panel controls in automobiles. In A. G. Gale et al. (Eds.), Vision in vehicles, 2, (pp. 335–344). Amsterdam: Elsevier Science.

    2. Labiale, G. (1996). Complexity of in–car visual messages and driver's performance. In A. G. Gale et al. (Eds.), Vision in vehicles, 5, (pp. 187–194). Bron Cedex, France: INRETS.

    3. Miller, G. A. (1956). The magical number seven plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81–97.

    4. Wierwille, W. W., Hulse, M. C., Fischer, T. J., & Dingus, T. A. (1988). Strategic use of visual resources by the driver while navigating with an in–car navigation display system. XXII FISITA Congress Technical Papers: Automotive Systems Technology: The Future, 2, (pp. 2.661–2.675). Warrendale, PA: Society of Automotive Engineers.

    5. Salthouse, T. A. (1982). Adult cognition: An experimental psychology of human aging. New York: Springer–Verlag.

    6. Graham, R., & Mitchell, V. A. (1997). An evaluation of the ability of drivers to assimilate and retain in–vehicle traffic messages. In Y. I. Noy (Ed.), Ergonomics and safety of intelligent driver interfaces (pp. 185–201). Mahwah, NJ: Lawrence Erlbaum Associates.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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MESSAGE STYLES

Introduction: Message style refers to the way in which information is given to the driver. The information can be presented in an advisory manner ("command style") or in more of a descriptive manner ("notification style"). Command style messages inform drivers of a situation and suggest a particular action to take in response to a situation. Notification style messages simply inform drivers and allow them to determine the appropriate action on their own.

Design Guidelines****
  • Command style messages promote compliance and should therefore be used for presenting safety–critical information that requires an immediate response.

  • Command style messages should be used infrequently, because they may cause drivers to over–rely on information given to them in– vehicle and to become complacent about searching the outside environment for out–of–vehicle information.

  • Notification style messages should be used for presenting low criticality information.

 

Decision Aid for Determining When to Use Each Message Style

 

Is the situation critical?

 

 

No

Yes

Is an
immediate
control
action necessary?

No

Notification
Style
Message

Notification
Style
Message

Yes

Notification
Style
Message

Command
Style
Message

 

X = (Speed (in km/h) x 1.637) + 14.799 (Equation 8)

Examples of Each of the Different Message Styles

Command Style:

"Slow Down"

"Move into the Right Lane"

Notification Style:

"Vehicle Ahead"

"Accident Ahead, 1/2 mile"

 

Supporting Rationale: In Reference 1, message style was investigated in order to determine its effect on driver compliance with warnings and driver safety. Results of the study indicate that the importance of the message should determine the message style to be used. For highly critical messages, command style should be used in order to increase the level of compliance. For less critical messages, notification style should be used, to ensure that the driver remains actively involved in the driving task. The urgency associated with making some type of control action should also be considered when determining the message style to be used. If the need for a control action is immediate and critical to the safety of the driver, then a command style message should be given. If, however, the need is not immediate or the control action is not necessary for the safety of the driver, then a notification style message would be more appropriate. In these cases, an "immediate" control action is defined as one which would occur after the preferred minimum distance for presenting information.

Reference 2 investigated the findings of Reference 1 in an on–the–road study. Again, high compliance was found for the command messages as compared to the notification messages.

Special Design Considerations: A study conducted in Reference 3 determined that including a combination of descriptive and advisory components in messages promotes the driver's situation awareness and decreases the amount of time necessary for making decisions. According to this study, increasing the amount of time necessary for reading the combined message was compensated by a decrease in the decision making time.

Reference 1 found that providing drivers with only roadside information does not generate very high driver compliance, while providing drivers with only ATIS information increases driver compliance but decreases safety. However, providing ATIS as well as roadside information was found to generate high driver compliance without the decrease in safety. Therefore, it is suggested that ATIS as well as redundant roadside information be given whenever possible.

Beyond the guidelines presented on the preceding page, developing ATIS messages is a process that should involve careful consideration of the message content, complexity, priority, and the consequences of a missed or misunderstood message.

Cross References:

Timing of Auditory Navigation Information

Key References:

    1. Lee, J. D., Stone, S. R., Gore, B. F., Colton, C., Macauley, J., Kinghorn, R. A., Campbell, J. L., Finch, M., & Jamieson, G. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Design alternatives for in– vehicle information displays: Message style, modality and location. Washington, DC: Federal Highway Administration (FHWA–RD–96– 147).

    2. Kantowitz, B. H., Hooey, B. L., & Simsek, O. (1998). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: On road evaluation of ATIS messages (Contract No. DTFH61–92–C–00102). Seattle, WA: Battelle Human Factors Transportation Center.

    3. Fain, W. B. (1995). Analysis of the influence of traffic information messages on route selection. Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting, (pp. 1082–1086). Santa Monica, CA: Human Factors and Ergonomics Society.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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DESIGN OF HEAD–UP DISPLAYS FOR ATIS

Introduction: The automotive HUD is an electro–optical device that presents both static and dynamic symbology and/or graphics in the driver's forward FOV. Presenting navigation information to drivers through HUDs is possible due to recent developments in automotive design, electronic instrumentation, and optics.

HUDs have the potential to improve driving performance and driver safety in a variety of ways. First, since the HUD is close to the driver's nominal line of sight (LOS), it allows the driver to sample both vehicle and driving information without the same accommodative shift required by conventional instrument clusters or head–down displays (HDDs). Second, it has the potential to reduce eyes–off–the–road time, by presenting relevant driving information at or near the forward LOS. However, since the initial development of prototype automotive HUDs, there has been a concern that the presence of the HUD image may interfere with the driving task and negatively impact driving performance. These concerns have developed from four main sources: (1) analogies to military HUD environments; (2) speculative common–sense notions that any image in the driver's forward LOS may affect visual performance and vehicle control judgments; (3) the subjective experience of some individuals indicating that the HUD image compels high visual attention on initial exposure to the display; and (4) suggestions that the HUD might represent a glare source that may decrease forward preview distance during very low ambient luminance nighttime driving.

Recent research into the question of safety with automotive HUDs has produced mixed results (see Reference 1). A recent study, however, that investigated the safety and applicability of using HUDs for ATIS applications did not indicate any distraction effects associated with an automotive HUD (Reference 2).

Design Guidelines****

Design Element

Guideline

Image Viewing Distance

  • Locate the HUD image 2.35 to 2.80 meters from the design–eye–position of the HUD.

Image Distortion

  • No HUD element should vary from its intended size by more than +/- 10%.
  • No point on the HUD display should be displaced by more than 5% of the total image width or height (horizontal or vertical FOV).

Luminance Adjustment Control
(see equation below)

  • A luminance adjustment control for the HUD image should be provided.
  • A continuous rotary knob, slide, or a thumbwheel should be the type of control provided for this adjustment.
  • Luminance values, as a function of control position, should be derived from a power function (see equation below).

 

The Luminance Control Function for an Automotive HUD

Footlambert = [(P x Lmax0.33) + ((1-P) x (Lmin0.33))] (1 ) 0.33) (Eq. 9)

where:

P = the proportion of total control movement

Lmax = maximum luminance provided

Lmin = minimum luminance provided

Supporting Rationale: Image Distance. Typical fixation distances while driving are 25 meters (Reference 3), or about 0.04 diopters (D) accommodation. Average depth–of–focus values, for representative stimuli and visual conditions, are 0.63 diopters (Reference 4). Therefore, for normal eyes during most driving situations, little or no change in accommodation is required from 2.8 meters to optical infinity [0.04 +/– (0.63/2) = –0.275D (far focus) and + 0.355D (near focus); 1 ) 0.355 = 2.8D]. For the purpose of reducing or eliminating accommodation requirements, the image distance of the HUD should be 2.8 meters or beyond. Depending on the visual angle between the HUD symbology and objects of interest in the visual scene, and on assumptions about driving scene fixation distances, image distance values representing tolerable binocular lateral disparity range from approximately 2.35 meters to 8.03 meters (References 5 and 6). These values represent estimates of tolerable disparity when an observer attempts to fixate on both the HUD and the external driving scene at the same time. Since drivers should not need to fixate on both the HUD and the external driving scene at the same time, these values are very conservative (i.e., less–conservative assumptions would allow the HUD to be closer to the driver).

Image Distortion. References 7 and 8 indicate that CRT symbols that are intended to be the same size should not vary in size by more than +/– 10 percent in either the vertical or horizontal dimension. Reference 9 also indicates that no point on a display should be displaced with respect to orientation or position by more than 5 percent of total image width or height. The design guidelines provided above reflect these standard human factors design guidelines.

Luminance Adjustment Control. Expected variations in HUD background luminances, as well as differences among drivers in terms of preferences and visual capabilities, suggest that drivers should be able to make minimal adjustments to the HUD luminance. Since continuous control of luminance over discrete luminance ranges is required, either a continuous rotary control, slide, or a thumbwheel type of control should be used (References 9 and 10). Although of less importance during daytime conditions, drivers will be able to avoid display–produced glare at night more easily if the luminance gain function follows the power function originally described in Reference 11. The luminance control functions depicted above will lead to the perception, by the driver, of approximate linearity between display brightness and the position of the luminance control.

Cross References:

Color Contrast

Key References:

    1. Gish, K. W., & Staplin, L. (1995). Human factors aspects of using head–up displays in automobiles: A review of the literature. Washington, DC: National Highway Traffic Safety Administration (DOT HS 808 320).

    2. Hooey, B. L., & Gore, B. F. (1998). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Head–up displays and driver attention for navigation information. Washington, DC: Federal Highway Administration (FHWA –RD–96–153).

    3. Mourant, R. R., & Rockwell, T. H. (1970). Mapping eye–movement patterns to the visual scene in driving: An exploratory study. Human Factors, 12, pp. 81–87.

    4. Ogle, K. N., & Schwartz, J. T. (1959). Depth of focus of the human eye. Journal of the Optical Society of America, 49, pp. 273 –280.

    5. Bell, H. H., & Ciuffreda, K. J. (1985). Advanced simulator for pilot training: Effects of collimation on accommodation and convergence (AD–A159 545/3). Brooks Air Force Base, TX: Air Force Human Resources Laboratory.

    6. Ogle, K. N. (1972). Researches in binocular vision. New York: Hafner.

    7. American National Standards Institute. (1988). American national standard for human factors engineering of visual display workstations. Santa Monica, CA: Human Factors and Ergonomics Society.

    8. Meister, D. (1984). Human engineering data base for design and selection of cathode ray tube and other display systems (NPRDC TR 84 –51). San Diego, CA: Navy Personnel Research and Development Center (DTIC No. AD–A145704).

    9. MIL–STD–1472D. (1989). Human engineering criteria for military systems, equipment, and facilities. Washington, DC: U.S. Government Printing Office.

    10. Chapanis, A., & Kincade, R. G. (1972). Design of controls. In H. P. Van Cott & R.G. Kincade (Eds.), Human engineering guide to equipment design (rev. ed.) (pp. 345–370). Washington, DC: U.S. Government Printing Office.

    11. Stevens, S. S. (1957). On the psychophysical law. Psychological Review, 64, pp. 153–181.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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TAILORING OF ATIS INFORMATION TO INDIVIDUAL PREFERENCES

Introduction: The tailoring of ATIS information to individual preferences refers to a driver's ability to personalize or to adjust ATIS design parameters to suit their individual driving habits, needs, and preferences.

Design Guidelines***

Drivers should be able to tailor the presentation of ATIS information to their own preferences and driving requirements, particularly for information requiring immediate compliance.

 

The Effect of Information Availability, Age, Gender, and Display Location on Trust

The Effect of Information Availability, Age, Gender, and Display Location on Trust

 

Supporting Rationale: References 1 and 2 describe the strong influence that trust can play in users' reaction to, and performance with, a complex system. In particular, levels of trust can affect sampling strategies, as well as the ultimate use of the system. In Reference 3, ATIS warning messages were presented to drivers using a driving simulator equipped with a reconfigurable ATIS. The visual scene was controlled to present drivers with roadway information in a form similar to the changeable message signs found on highways. ATIS information was presented in either a centralized location (a single, center–mounted CRT screen) or in distributed locations (CRT, head–down instrument panel, head–up display). Information availability refers to the medium by which sign information was made available to the drivers. Four options were investigated: (1) ATIS presentation only, (2) roadway sign only, (3) ATIS presentation and roadway signs, and (4) neither ATIS presentation nor roadway signs. In the study, driver trust and confidence in the presented information was assessed using a variety of subjective indices. The results (the figure on the opposing page and the table below provide an example) showed wide variability in trust and self–confidence as a function of age and gender. This general finding was repeated across a range of experimental conditions (message style, information availability, information modality) and relevant subjective measures (rated self–confidence, situational awareness, and mental effort).

 

Specific Effects of Age and Gender on ATIS Devices.

Gender

Younger

Older

Female

A crossover interaction indicates that the trust of young females drops more with centralized displays.

The trust of older females drops more with distributed displays, remaining almost unaffected with the centralized displays.

Male

The trust of young males drops more with the distributed displays.

The trust of older males remains relatively constant for both the centralized and distributed displays and only declines slightly when ATIS and roadway information were not present.

 

Special Design Considerations: The precise ATIS design parameters that should be adjustable by individual drivers have not been extensively studied. Moreover, without additional empirical data, it is difficult to know how such "personalization" of an ATIS device should be accomplished. In general, issues that must be addressed include decrements in visual acuity associated with older drivers (e.g., requirements for larger fonts), and an over–reliance on ATIS information associated with younger subjects.

Cross References:

ATIS Design for Special Populations

Key References:

    1. Lee, J. D., & Moray, N. (1992). Trust and the allocation of function in the control of automatic systems. Ergonomics, 35, pp. 1243 –1270.

    2. Lee, J. D., & Moray, N. (1994). Trust, self–confidence, and operators' adaptation to automation. International Journal of Human –Computer Studies, 40, pp. 153–184.

    3. Lee, J. D., Stone, S. R., Gore, B. F., Colton, C., Macauley, J., Kinghorn, R. A., Campbell, J. L., Finch, M., & Jamieson, G. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Design alternatives for in– vehicle information displays: Message style, modality and location. Washington, DC: Federal Highway Administration (FHWA–RD–96– 147).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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ATIS DESIGN FOR SPECIAL POPULATIONS

Introduction: ATIS design for special populations refers to design criteria aimed specifically at drivers with either sensory or cognitive disabilities that might affect their ability to effectively use the system. One such population is the older drivers, those over the age of 60. There is a considerable body of research showing that the older population has numerous cognitive and sensory deficits. Other special populations include handicapped or disabled drivers as well as those people with minor cognitive impairments. In many cases, the suggestions made for improving ATIS design for these populations would increase its usability for the general population as well.

Design Guidelines**
  • Use only simple, 3 or 4 information unit messages. (The phrase "information units" is used to describe the amount of information presented in terms of key nouns and adjectives contained within a message. The design guideline entitled "Auditory Message Length" on page 3–26 provides a tool for determining the number of information units.)

  • Warnings should be available in alternative forms (i.e., visual, auditory, or tactile), allowing both visual and hearing impaired persons to adapt the signal to their perceptual characteristics.

  • Drivers should be able to have the system repeat messages.

  • Systems should provide the means for attaining larger displays or enlarging images in order to adapt the visual output to the users needs. For the same reasons, the volume of auditory systems should also be adjustable.

  • Allow drivers to select multiple, redundant modalities for message presentation (i.e., both visual and auditory).

 

Potential Benefits of ATI Subsystems for Special Populations

System

Potential Benefits/Problems Addressed

Route Guidance

Could be helpful for older drivers suffering from the mild memory deficits typical of normal aging or for those suffering from the early stages of Alzheimer's. The route guidance subsystem would help drivers to remember routes and road names.
Trip Planning Might be helpful for older drivers, whose ability to process information has slowed. The trip planning subsystem would help reduce the cognitive load placed on the driver, lowering the crash potential while in–transit.
Mayday/Aid Request Could be especially helpful for elderly or disabled drivers, who might be limited in their ability to move or respond in an emergency situation. The mayday/aid request subsystem could automatically contact the correct emergency personnel and transmit all of the necessary location information.
In–Vehicle Signage Might be helpful for older drivers, especially during night driving. It has been reported that the visual acuity of older drivers can drop dramatically (20/140) when they are subjected to decreased illumination. The in–vehicle signage subsystem would present on–road traffic signs inside the vehicle in order to enhance visibility.

 

Supporting Rationale: Reference 1 presents several recommendations for improving ATIS devices to be used by older drivers. Suggestions are made for reducing message complexity by eliminating unnecessary information or words in a message. Three– or four–element messages were found to be most satisfactory in terms of safety, usefulness, and driver acceptability. A simulator study summarized in Reference 2 found that the differences in performance between young and older drivers increase as a function of information complexity. It also recommends breaking complex pieces of information down into several smaller information units.

Reference 1 also found that increasing the amount of time that information is displayed and allowing drivers to repeat messages if necessary were beneficial for older drivers whose cognitive speeds are slightly slower. Short breaks in between messages were also found to be helpful for older drivers, in that it gave them the time they needed to reorient themselves to the roadway ahead and reduced the number of glances away from the forward roadway. The study completed in Reference 1 found that older subjects were open to the idea of an ATIS device but encountered problems when it came to reading, encoding, and retaining complex messages. The results suggested that the visual problems could be overcome by allowing the driver to adjust controls for brightness, contrast, and saturation of the screen to their own personal preference.

Special Design Considerations: Reference 3 suggests that allowing the system to be flexible so that it can be set to match a drivers preference is very important, and states that "uniform settings would be at best unhelpful, at worst dangerous." An on–road study completed in Reference 4 suggests that allowing drivers to select the type of message they would like to receive and to decide whether or not it would be redundant might help the older driver. In this way, the drivers are allowed to make the message seem as urgent as they feel is necessary. Older drivers may perceive being off–route as being more urgent than younger drivers.

Reference 5 examined latency and recall for auditory messages (earcons, verbal messages, and complex tones) for older and younger subjects. Older subjects were unable to achieve adequate recognition performance for the sounds during training. Thus, older drivers may have difficulties recalling the meaning of auditory messages under real–world driving conditions.

Cross References:

Auditory Message Length

Complexity of ATIS Information

Tailoring of ATIS Information to Individual Preferences

Key References:

    1. Graham, R., & Mitchell, V. A. (1997). An evaluation of the ability of drivers to assimilate and retain in–vehicle traffic messages. Y. I. Noy (Ed.), Ergonomics and safety of intelligent driver interfaces (pp. 185–201). Mahwah, NJ: Lawrence Erlbaum Associates.

    2. Marin–Lamellet, C., & Dejeammes, M. (1995). The processing of complex guidance symbols by elderly drivers: A simulator based study and an evaluation of the CARMINAT guidance system by the European Community DRIVE–EDDIT Project. Proceedings of the 6th Vehicle Navigation and Information Systems Conference (pp. 10–117). Piscataway, NJ: IEEE.

    3. Oxley, P. (1996). Elderly drivers and safety when using IT systems. IATSS Research, 20(1), (pp. 102–110). Berkeley, CA: University of California at Berkeley.

    4. Hanowski, R. J., Gallagher, J. P., Kieliszewski, C. A., Dingus, T. A., Biever, W., & Neale, V. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Driver response to unexpected situations when using an in –vehicle information system (Contract No. DTFH61–92–C–00102). Blacksburg, VA: Center for Transportation Research, VPI & SU.

    5. Kantowitz, B. H., Hanowski, R. J., Kantowitz, S. C., & Garness, S. A. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Display channels. Washington, DC: Federal Highway Administration (FHWA–RD –96–148).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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DESIGN OF ATIS SUBSYSTEM INTERFACES

Introduction: Design of ATIS subsystem interfaces refers to the consistency of the "look and feel" associated with the ATIS driver–vehicle interface (DVI), across various functions within the ATIS. For example, a single ATIS device could include trip planning, route guidance, travel coordination, and message transfer functions, much as modern computer systems include word processing, graphics, and e–mail applications. The degree of integration or consistency refers to the color schemes, fonts, layouts, and control operations associated with these different functions. A fully integrated system would have a common user interface, with the same colors, formats, and control operations; in a non–integrated system, these features could vary from function to function.

Design Guidelines***
  • When the vehicle is in PARK, a nonintegrated ATIS device will result in acceptable performance.

  • A nonintegrated ATIS interface can also be used for non–in–vehicle ATIS applications such as Internet, hotel, portable and kiosk devices.

 

Examples of Both Integrated and Nonintegrated ATIS DVIs from Comparable ATIS Functions

Examples of Both Integrated and Nonintegrated ATIS DVIs from Comparable ATIS Functions

 

Supporting Rationale: In Reference 1, user performance and cognitive demands were investigated in a study that included both integrated and nonintegrated ATIS interfaces. In various predrive scenarios, subjects were asked to plan trips, select routes, select modes of travel, make reservations, and respond to messages during a PC–based ATIS simulation. For the predrive scenarios investigated, no differences were found between the integrated and non–integrated systems in terms of performance (time to plan the trip, number of errors, requests for system help) or cognitive demands (understanding of the system, difficulties in navigating across system functions). Since out–of–vehicle ATIS applications such as Internet, hotel, portable and kiosk devices are, by definition, "predrive," nonintegrated ATIS functions can also be used in these applications.

Special Design Considerations: Although Reference 1 has determined that nonintegrated ATIS devices can be used without decrements in performance or increases in cognitive demands, user acceptance concerns may favor a more integrated approach to the design of the ATIS interface. For example, computer users have come to expect a certain consistency across the user interface as they move from application (e.g., word processing) to application (e.g., spreadsheets) on their computer. Thus, different applications may use the same keystrokes to perform similar functions, such as the standardized use of Ctrl+C for copy and Ctrl+V for paste. Similarly, for aesthetic and user acceptance reasons, ATIS designers should use a common "look and feel" across ATIS functions whenever feasible.

Cross References: None.

Key References:

    1. Campbell, J. L., Hanowski, R. J., Hooey, B. L., Gore, B. F., & Kantowitz, B. H. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: ATIS function transitions. Washington, DC: Federal Highway Administration (FHWA–RD–96–146).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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GENERAL GUIDELINES FOR USER INTERFACE DESIGN

Introduction: User interface design refers to the system design characteristics of a computer–based system that includes the screen layout and format, selection of icons, use of borders and windows, control selection and placement, and the procedures and "rules" that define transactions between the system and the user.

Design Guidelines **

General Guideline
(adapted from References 1 and 2)

Possible ATIS/CVO Application

Make objects, actions, and options visible to the user.

Choices for transit mode (e.g., train, bus, or ferry) should all be identified and selectable to the user on a single screen or an obviously linked set of screens.

Provide error messages in plain language, and indicate the precise problem.

If a driver enters an address (for trip planning purposes) that does not exist, rather than a message such as "Error in Input," use " That Address Does not Exist."

Users should not have to remember information across dialogs.

For interactions involving more than one related screen organized in a hierarchical fashion, such as restaurant selections, key information or user-entered information should be carried from screen to screen.

Conduct frequent testing of the user interface, recognize that system designers are not representative users of the final system.

Even small changes (e.g., changes in screen layout, color, or menu hierarchy) can have a significant effect on user acceptance and performance. Conduct testing with representative users at critical design stages and when key design elements are changed.

Provide undo and redo functions that support corrections to user input as well as recovery from errors.

When complicated inputs are made, such as entering destinations or selecting travel modes, provide "Back," "Delete," or "Undo" buttons, or functions that allow the user to recover from errors and re–enter information.

Objects on the screen that look the same should act the same.

Do not use the same symbol (e.g., a fuel pump) for both a descriptive display icon and a control button that prompts the system to perform some action.

Every user action should result in a reaction from the system.

Provide understandable visual or auditory feedback in response to user inputs in the form of: changes to data fields, changes to another screen within the menu hierarchy, or a dialogue message.

If an item on the display must be remembered, flag or display it in a salient and meaningful manner.

Key roadway features such as construction zones and congested roadways (or destinations for the CVO driver) should be highlighted with unique colors and/or icons.

 

Supporting Rationale: In Reference 1, human–computer interaction (HCI) designers were surveyed to identify maxims that they found to be useful during their user interface design activities. A final list of 34 maxims was then sent to members of the American National Standards Institute (ANSI) committee and other HCI designers, who were asked to rate each maxim on its impact on the usability of computer systems. Some of the guidelines above represent the maxims that were rated as the most implementable and having the greatest impact on usability.

Other guidelines listed above were adapted from a larger set of broad user interface design principles provided in Reference 2, which summarizes principles from cognitive psychology and applies these principles to problems of user interface design in office systems.

Special Design Considerations: These guidelines are very general and should be implemented in a careful and purposeful manner. Application to specific design issues should reflect the goals, requirements, and constraints of individual design efforts.

Cross References:

Number of Control Actions for Commercial Driver ATIS Tasks

Key References:

    1. Lund, A. M. (1997). Expert ratings of usability maxims. Ergonomics in Design, 5(3), pp. 15–20.

    2. Marshall, C., Nelson, C., & Gardiner, M. M. (1987). Design guidelines. In M. M. Gardiner & B. Christie (Eds.), Applying cognitive psychology to user–interface design (pp. 221–278). New York: J. Wiley & Sons.

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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GENERAL GUIDELINES FOR ATIS MESSAGES

Introduction: ATIS messages refer broadly to information items that are presented to the driver through an ATIS device. They include information relevant to navigation, motorist services, congestion, safety, augmented signage, weather, or caution/alert messages.

Design Guidelines**
  • Avoid using text–only display formats, except when presenting information such as directions for navigation and restaurant options, departure times, and other nongraphic information.

  • When presenting information about an upcoming event, such as a turn, a desired exit, or a construction zone, present the information in terms of both time to the event and one other relevant parameter such as number of preceding intersections or miles to the event. Do not present the event information only in terms of time to the event.

  • When presenting information about an upcoming event, such as a turn, use 2–3 warning messages to the driver regarding the need for a turn. Do not use only one warning message.

 

Example of ATIS Message Options Evaluated in Reference 1

Example of ATIS Message Options Evaluated in Reference 1

 

CVO drivers were asked to rank these three displays in order of their preferences. They were asked to assign a "1" to the most preferred display, a "2" to the second most preferred display, and a "3" to the least preferred display. As seen above, the combined text/graphic display had the best rating, with a mean rating of 1.10.

Supporting Rationale: In Reference 1, both a survey and a user clinic were conducted to evaluate display formats for several types of ATIS displays in order to identify driver population stereotypes and preferences. The survey was a paper-and-pencil questionnaire that obtained information from rural, urban, and commercial drivers on priorities, preferences, and suggested formats for ATIS information. Information elements included in the survey included motorist services, time/distance to destination, guide signs, road construction, navigation, congestion, emergency vehicle notification, and regulatory information. The user clinic was a computer simulation designed to determine presentation comprehension and driver preferences in a dynamic driving scenario. Information elements included in the user clinic included yellow pages, restaurant description and costs, alternative route displays, and alerts for accidents, congestion, and weather. The guidelines above reflect the key results from the survey and user clinic.

Special Design Considerations: The guidelines presented here are preliminary and general, and should be implemented in a careful and purposeful manner. Application to specific design issues should reflect the goals, requirements, and constraints of individual design efforts.

Cross References:

Sensory Modality for Presenting ATIS/CVO Messages

Symbol Versus text Presentation of ATIS/CVO Messages

Timing of Navigation Information

Key References:

    1. Neale, V. L., Dingus, T. A., Schroeder, A. D., Zellers, S., & Reinach, S. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Advanced traveler information system feature standardization. Washington, DC: Federal Highway Administration (FHWA–RD–96–149).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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USE OF ALERTS FOR ATIS MESSAGES

Introduction: Alerts for ATIS messages refers to information presented to drivers prior to, or concurrent with, the presentation of an ATIS message. Alerts are typically used to notify drivers of high–priority ATIS messages associated with safety (e.g., immediate hazard, emergency vehicle approaching), vehicle status (e.g., vehicle condition warning), or augmented signage information (e.g., guidance, notification, or regulatory signs).

 

Selected Results From Key References

Selected Results From Key References

 

Selected Results From Key References

 

From Reference 1––a visual ATIS message, preceded by an auditory alerting tone, was associated with higher compliance levels than a visual message alone.

From Reference 2––auditory alerts were associated with better performance than no alerts. If no alert can be provided and the message is high priority, an auditory message should be used.

Supporting Rationale: In Reference 1, a simulator study was performed in which drivers were informed of upcoming speed zones (i.e., construction zone and school zone) approximately 7.1 seconds before reaching a corresponding roadway sign. The advanced warning was given to the driver in one of two ways, either a text message on an in–vehicle display or a text message preceded by an auditory tone. The results of this study indicated that 9 of the 12 drivers who received only a visual warning either never slowed to the goal speed or slowed only after they had passed the sign located on the roadway. In contrast, 10 of the 12 drivers who received the combination visual and auditory warning were able to slow to the goal speed well in advance of the roadway sign. Therefore, these results suggest that for the presentation of notification sign information which advises drivers to make changes in their current speed of travel, the combination of an auditory alerting tone and ATIS textual information may lead to faster and more reliable compliance.

In Reference 2, subjects were trained to recall six complex sounds (earcons) and six visual icons that were part of an experiment investigating ATIS devices. These earcons and icons, along with speech and textual messages, were then presented to subjects while they navigated through a simulated driving environment in a fixed–base driving simulator. Twelve of the subjects received a speech alert before all message presentations, 12 of the subjects received a tone alert, and 12 of the subjects received no alert at all. Performance measures included: response times to a recognition question on the message, accuracy in recognizing the meaning of a message, and confidence in their answers. Results suggested that subjects in the no alert group were significantly less accurate, slower, and less confident with the visual messages than they were with the auditory messages. Performance in the speech alert and tone alert groups did not differ. These findings suggest that alerts of some type will improve accuracy, latency, and confidence associated with visual messages.

Special Design Considerations: The guidelines presented here are preliminary and general, and should be implemented in a careful and purposeful manner. Application to specific design issues should reflect the goals, requirements, and constraints of individual design efforts.

Cross References:

Sensory Modality for Presenting ATIS/CVO Messages

General Guidelines for ATIS Messages

Timing of Navigation Information

General Guidelines for Augmented Signage Information

Key References:

    1. Kantowitz, B. H., Simsek, O., & Carney, C. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: ATIS function transitions (Contract No. DTFH61–92–C–00102). Seattle, WA: Battelle Human Factors Transportation Center.

    2. Kantowitz, B. H., Hanowski, R. J., Kantowitz, S. C., & Garness, S. A. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Display channels. Washington, DC: Federal Highway Administration (FHWA–RD–96–148).

*Primarily expert judgement
**Expert judgement with supporting empirical data
***Empirical data with supporting expert judgement
****Primarily empirical data

 

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FHWA-RD-98-057

 

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