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

General Guidelines for Augmented Signage Information

Key References:

1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).

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

PRESENTATION OF GUIDANCE SIGN INFORMATION

Introduction: Guidance sign information refers to information which helps to guide a driver to a particular destination. This information is normally found in the out–of–vehicle environment (e.g., street signs, interchange graphics, route markers, and mile posts). However, with augmented signage information, this information is brought into the vehicle and displayed to the driver.

Design Guidelines**
Information Element	Display Type	Trip Status	Display Format
Sign information (e.g., street signs, interchange graphics, route markers, and mile posts)	Auditory or Visual	Vehicle in Motion	Alerting tone then speech, or speech or alerting tone, then icon
Sign information associated with driving to the destination	Auditory or Visual	Vehicle in Motion	Alerting tone then speech, or speech or alerting tone, then icon

Schematic Examples of Guidance Sign Information

Each of the roadway guidance sign examples shown below could
be presented to the driver in the form of a brief auditory message. An
example of such an auditory message is shown as well.

Schematic Examples of Guidance Sign Information

Timing requirements for Signage Information are uncertain. See also the guideline on
"Timing of Navigation Information," for more information on timing.

Supporting Rationale: Reference 1 used a literature review, an analysis, and the results of applying a research–based design tool to identify the most appropriate display type, trip status, and display format to use when displaying guidance sign information. The nature of this information precludes it from being presented at any time other than in transit. Information complexity is the main factor in determining the sensory modality most appropriate for presenting the information. When presenting complex sign information relating to vehicle safety, an iconic or graphical representation supplemented with voice is the preferred presentation. The potential complexity of this information precludes an auditory format. However, when the information is not safety related, icons with tones are preferred. Therefore, voice is preferred for presenting information related to more infrequent and important events, such as guidance sign information. As the information presented becomes simple, information should be presented through the auditory channel alone. Care should be taken, however, not to present too much unwanted or unnecessary information, as this could quickly aggravate or overload the driver's auditory resources.

Special Design Considerations: It has been theorized that rather than completely processing all of the signs along the roadway, drivers selectively attend to those which are most applicable to their current driving situation. Certain information, such as the current street, might become annoying to drivers if presented too frequently. Therefore, it might be worthwhile to allow drivers to selectively filter the sign information which will be presented to them in–vehicle as well. This ability will protect drivers from the possibility of information overload and annoyance.

Selection of the auditory versus visual mode for this information should reflect consideration of priority, complexity, and the consequences of a missed message.

Guidelines for guidance sign information for ATIS reflect certain assumptions regarding the priority, length, and complexity of messages. These assumptions may not apply to all design situations.

Cross References:

Relationship Between ATIS Information and Roadway Signs

General Guidelines for Augmented Signage Information

Key References:

1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).
2. Simpson, C. A., McCauley, M. E., Roland, E. F., Ruth, J. C., & Williges, B. H. (1987). Speech controls and displays. In G. Salvendy (Ed.), Handbook of human factors (pp. 549–574). New York: J. Wiley & Sons.
3. Labiale, G. (1990). In–car road information: Comparisons of auditory and visual presentation. Proceedings of the Human Factors Society 34th Annual Meeting (pp. 623–627). Santa Monica, CA: Human Factors and Ergonomics Society.
4. Sorkin, R. D., & Kantowitz, B. H. (1987). Speech communication. In G. Salvendy (Ed.), Handbook of human factors (pp. 294– 309). New York: J. Wiley & Sons.

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

PRESENTATION OF NOTIFICATION SIGN INFORMATION

Introduction: Notification sign information refers to information which notifies drivers of potential hazards or changes in the roadway. This information will be presented to the driver in–vehicle. Examples of this information will include: merge signs, advisory speed limits, chevrons, and curve arrows. In addition, notification information may include temporary or dynamic information such as road closures, road maintenance, or road construction. Other supplementary information such as the distance to a notification point may also be provided.

Design Guidelines***
Information Element	Display Type	Trip Status	Display Format
Inform driver of changes in the roadway (e.g., merge signs, advisory speed limits, chevrons, curve arrows)	Auditory and Visual	Vehicle in Motion	Auditory alerting tone followed by icon or text message
Inform driver of temporary or dynamic information (e.g., road closures, road maintenance or road construction)	Auditory or Visual	Vehicle in Motion	Alerting tone then speech, or speech or alerting tone, then icon
Inform driver of distance to a particular notification point	Auditory	Vehicle in Motion	Speech, or alerting tone, then speech

Schematic Examples of Notification Sign Information

Each of the roadway notification sign examples shown below could
be presented to the driver in the form of a brief auditory message. An
example of such an auditory message is shown as well.

Schematic Examples of Notification Sign Information

Timing requirements for Signage Information are uncertain. See also the guideline on
"Timing of Navigation Information," for more information on timing.

In Reference 2, 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 15 of the 18 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, 12 of the 18 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.

Special Design Considerations: It has been theorized that rather than completely processing all of the signs along the roadway, drivers selectively attend to those which are most applicable to their current driving situation. Therefore, it might be worthwhile to allow drivers to selectively filter the sign information which will be presented in–vehicle as well. The ability to do this will protect drivers from the possibility of information overload.

Research done to date, regarding the presentation of auditory messages indicates that aural messages should be comprised of a minimum of four syllables to provide sufficient linguistic context for comprehension (Reference 3), but limited to 7 to 9 units (Reference 4). Also, for increased intelligibility, Reference 5 suggests that sentences be used instead of isolated words. Guidelines for notification sign information for ATIS reflect certain assumptions regarding the priority, length, and complexity of messages. These assumptions may not apply to all design situations.

Cross References:

Relationship Between ATIS Information and Roadway Signs

General Guidelines for Augmented Signage Information

Key References:

1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).
2. 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.
3. Simpson, C. A., McCauley, M. E., Roland, E. F., Ruth, J. C., & Williges, B. H. (1987). Speech controls and displays. In G. Salvendy (Ed.), Handbook of human factors (pp. 549–574). New York: J. Wiley & Sons.
4. Labiale, G. (1990). In–car road information: Comparisons of auditory and visual presentation. Proceedings of the Human Factors Society 34th Annual Meeting (pp. 623–627). Santa Monica, CA: Human Factors and Ergonomics Society.
5. Sorkin, R. D., & Kantowitz, B. H. (1987). Speech communication. In G. Salvendy (Ed.), Handbook of human factors (pp. 294– 309). New York: J. Wiley & Sons.

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

PRESENTATION OF REGULATORY SIGN INFORMATION

Introduction: Regulatory sign information refers to information found on out–of–vehicle signage which helps to regulate traffic and displays the rules of the road. This information can also be presented to the driver in–vehicle. Examples of this information include: speed limit signs, stop signs, yield signs, turn prohibitions, and lane use control (e.g., left turn only).

Design Guidelines***
Information Element	Display Type	Trip Status	Display Format
Inform driver of regulatory information (e.g., stop signs, speed limits, yield signs, turn prohibitions, and lane use controls)	Auditory and Visual	Vehicle in Motion	Alerting tone then speech, or speech or alerting tone, then icon

Schematic Examples of Regulatory Sign Information

Each of the regulatory sign examples shown below could
be presented to the driver in the form of a brief auditory message. An
example of such an auditory message is shown as well.

Schematic Examples of Regulatory Sign Information

Timing requirements for Signage Information are uncertain. See also the guideline on
"Timing of Navigation Information," for more information on timing.

In Reference 2, 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 15 of the 18 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, 12 of the 18 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 regulatory 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.

Special Design Considerations: When displaying sign information in–vehicle, allow a driver to selectively filter the information to protect drivers from the possibility of information overload. However, regulatory sign information is important for the safe and legal operation of the driver's vehicle, and filtering this information could lead to traffic citations or even accidents. Therefore, the filtering option given for both the notification and guidance sign information is not suggested for the regulatory sign information.

Research done to date regarding the presentation of auditory messages indicates that aural messages should be comprised of a minimum of four syllables to provide sufficient linguistic context for comprehension (Reference 3), but limited to 7 to 9 units (Reference 4). Also, for increased intelligibility, Reference 5 suggests that sentences be used instead of isolated words. Guidelines for regulatory sign information for ATIS reflect certain assumptions regarding the priority, length, and complexity of messages. These assumptions may not apply to all design situations.

Cross References:

Relationship Between ATIS Information and Roadway Signs

General Guidelines for Augmented Signage Information

Key References:

1. Hulse, M. C., Dingus, T. A., Mollenhauer, M. A., Liu, Y., Jahns, S. K., Brown, T., & McKinney, B. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Identify strengths and weaknesses of alternative information display formats. Washington, DC: Federal Highway Administration (FHWA–RD–96–142).
2. 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.
3. Simpson, C. A., McCauley, M. E., Roland, E. F., Ruth, J. C., & Williges, B. H. (1987). Speech controls and displays. In G. Salvendy (Ed.), Handbook of human factors (pp. 549–574). New York: J. Wiley & Sons.
4. Labiale, G. (1990). In–car road information: Comparisons of auditory and visual presentation. Proceedings of the Human Factors Society 34th Annual Meeting (pp. 623–627). Santa Monica, CA: Human Factors and Ergonomics Society.
5. Sorkin, R. D., & Kantowitz, B. H. (1987). Speech communication. In G. Salvendy (Ed.), Handbook of human factors (pp. 294– 309). New York: J. Wiley & Sons.

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

GENERAL GUIDELINES FOR AUGMENTED SIGNAGE INFORMATION

Introduction: Augmented signage information refers to transportation technologies that use in–vehicle displays to present the driver with noncommercial routing, warning, regulatory, and advisory information that is currently presented on external roadway signs (Reference 1).

Design Guidelines***

Augmented signage information should be presented in a manner that allows drivers sufficient time to interpret the message, determine an appropriate response, and to make that response. [In Reference 2, in-vehicle messages were presented 3-5 seconds before the external road sign (or a relevant roadway condition) was visible.]
If an auditory warning or attention signal is used to precede the visual presentation of the in-vehicle signage, the volume of the signal should be adjustable by the driver.
Drivers should be able to adjust the content of the information that is presented through the in-vehicle signage system; i.e., to suppress the presentation of information considered unimportant or distracting.

Augmented Signage Information Evaluated in Reference 2

Augmented Signage Information Evaluated in Reference 2

Supporting Rationale: In Reference 2, a field experiment was conducted to investigate the benefits of in–vehicle signing information under conditions where external factors reduce or eliminate the driver's ability to see external road signs. The study included both day and night driving conditions, rain and clear weather conditions, and younger and older drivers. All conditions were tested both with and without (i.e., just the standard external signs) the in–vehicle signage information. Three measures of driver performance were collected, as well as subjective data to determine driver preferences and acceptance associated with the in–vehicle displays. The results indicated that the in–vehicle signage information was associated with more appropriate speeds and greater reaction distance for all drivers, increased awareness of road sign information, and a high acceptance rate. No adverse effects associated with driver performance or vehicle control were found. However, some subjects (particularly younger drivers) found the auditory attention signal that preceded the visual in–vehicle signage information to be somewhat distracting and annoying.

In Reference 3, a simulation study was conducted to compare driver performance with in–vehicle versus roadside traffic signing under both foggy and clear ambient conditions. As in Reference 2, the in–vehicle signing condition led to faster driver responses (due to an earlier presentation to the driver), particularly for older drivers under foggy conditions. The study was not conclusive, yet (as with Reference 2) suggested some potential benefits of in–vehicle signing.

Special Design Considerations: Relatively little research has been conducted to investigate the driver performance implications of various design approaches to augmented signage systems. For example, the effects of information modality (auditory vs. visual), different locations within the vehicle for visual displays, and message timing relative to the location of external signs remain to be addressed by the research community. Timing is a particularly important issue that has not received sufficient empirical attention. In studies conducted to date, in–vehicle signage has been presented to drivers well before the corresponding roadway signs were legible. In these studies, faster driver responses to the in–vehicle versus roadway signs have been interpreted as a benefit of in–vehicle signage. However, this may not always be the case; in many driving situations, for example, premature braking responses can lead to crashes or other incidents. Thus, messages should be presented so that they allow sufficient time for a driver response, yet not be presented so early that drivers respond in a premature or inappropriate manner.

The guidelines presented here are preliminary, 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:

Presentation of Guidance Sign Information

Presentation of Regulatory Sign Information

Key References:

1. Perez, W. A., & Mast, T. M. (1992). Human factors and advanced traveler information systems (ATIS). Proceedings of the Human Factors and Ergonomics Society 36th Annual Meeting (pp. 1073–1077). Santa Monica, CA: Human Factors and Ergonomics Society.
2. Collins, D. J., Biever, W. J., Dingus, T. A., & Neale, V. L. (1997). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Driver performance and behavior interaction with ISIS under reduced visibility conditions (Contract No. DTFH61–92–C–00102). Blacksburg, VA: Center for Transportation Research, VPI & SU.
3. Marshall, R., & Mahach, K. (1996). The effects of an in–vehicle information system (IVIS) signing component on driver response to stop signs and traffic signals on a simulated rural highway. Proceedings of the Third Annual ITS World Congress. Orlando, FL: ITS AMERICA.

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