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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 9: COMMERCIAL VEHICLE OPERATIONS GUIDELINES

 

PRESENTATION OF CVO–SPECIFIC GUIDANCE SIGN INFORMATION

Introduction: CVO–specific guidance sign information refers to sign information which might be helpful for guiding commercial vehicle operators to a particular destination. Such information is currently found on out–of–the–vehicle signage (e.g., truck route signs). However, this subfunction would allow this information to be presented to the commercial driver aurally, in the vehicle.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Specific sign guidance (e.g., truck route)

Auditory

Vehicle in Motion

Alerting tone, then speech, or entire message presented as speech or alerting tone, then icon

Delivery location

Auditory

Vehicle in Motion

Alerting tone, then speech, or entire message presented as speech or alerting tone, then icon

 

Schematic Example of Presenting CVO–Specific Guidance Sign Information

Schematic Example of Presenting CVO-Specific Guidance Sign Information

 

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. It was determined that the nature of the information precludes it from being presented at any other time than in transit. The criticality of the information will determine which format will be used to display it. Although the information will always be presented through the auditory channel, information which is deemed to be more critical or unique (e.g., requiring immediate response) will be preceded by an alerting tone. Otherwise, the information will be given solely as a voice message. In this way, the distraction potential associated with these types of messages should be reduced.

Special Design Considerations: Research done to date regarding the presentation of auditory messages indicates that aural messages should be comprised of a minimum of 4 syllables to provide sufficient linguistic context for comprehension (Reference 2), but limited to 7 to 9 units (Reference 3). Also, for increased intelligibility, Reference 4 suggests that whole sentences be used instead of isolated words.

Rather than completely processing all of the signs along the roadway, CVO drivers selectively attend to those which are most applicable to their current driving situation. It might be worthwhile to allow a driver to selectively filter the sign information which will be presented to them in–vehicle, in order to protect drivers from the possibility of information overload.

It is important to note that very little research has been performed to evaluate different methods of displaying sign information with an in–vehicle system. The design guidelines given are based solely on generally accepted human factors guidelines and principles. To accurately assess the system effectiveness and user preferences, researchers should use prototypes of a signing system to clarify the decisions about which sensory mode to use for sign information display and the types of filtering that might be employed.

Cross References:

Use of Alerts for ATIS Messages

Timing of Auditory Navigation Information

Presentation of Filtering Sign Information

Trip Status Allocation Design Tool

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

 

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PRESENTATION OF CVO–SPECIFIC NOTIFICATION SIGN INFORMATION

Introduction: CVO–specific notification sign information refers to information regarding potential hazards and road changes. Particularly in the case of large trucks, additional time to plan or prepare for long/steep grades, sharp curves, exits, and lane changes may be valuable. Also, presenting this information in–vehicle may allow for it to be more detailed and timely.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Road change information (i.e., steep grade, sharp curve, or exit)

Auditory

Vehicle in Motion

Alerting tone, then speech, or entire message presented as speech, or alerting tone, then icon

 

Schematic Example of Presenting CVO–Specific Notification Sign Information

Schematic Example of Presenting CVO-Specific Notification Sign Information

 

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 notification sign information. It was determined that the nature of the information precludes it from being presented at any other time than in transit. Simple notification information should be presented through the auditory channel to avoid distracting the driver unnecessarily. More critical or unique notification messages (e.g., those requiring an immediate response) should be preceded by an auditory alert, in order to get the attention of the driver more quickly.

Special Design Considerations: Research done to date regarding the presentation of auditory messages indicates that aural messages should be comprised of a minimum of 4 syllables to provide sufficient linguistic context for comprehension (Reference 2), but limited to 7 to 9 unrelated informational items (Reference 3). Also, for increased intelligibility, Reference 4 suggests that sentences be used instead of isolated words.

Rather than completely processing all of the signs along the roadway, CVO 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 to them in–vehicle. The ability to filter sign information will help to protect drivers from the possibility of information overload.

It is important to note that very little research has been performed to evaluate different methods of displaying sign information with an in–vehicle system. The design guidelines given are based solely on generally accepted human factors guidelines and principles. To accurately assess the system effectiveness and user preferences, researchers should use prototypes of a signing system to clarify the decisions about which sensory mode to use for sign information display.

Cross References:

Use of Alerts for ATIS Messages

Timing of Auditory Navigation Information

Presentation of Filtering Sign Information

Trip Status Allocation Design Tool

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

 

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PRESENTATION OF CVO–SPECIFIC REGULATORY SIGN INFORMATION

Introduction: CVO–specific regulatory sign information refers to information regarding size and weight limits, truck speed limits, and any road restrictions.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Specific regulatory information for CVO's (e.g., truck speed limits, weight limits, etc.)

Auditory or Visual

Vehicle
in Transit

Alerting tone, then speech or entire message presented as speech or alerting tone, then icon

 

Schematic Example of Presenting CVO–Specific Regulatory Sign Information

Schematic Example of Presenting CVO-Specific Regulatory Sign Information

 

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 CVO–specific regulatory sign information. It was determined that the nature of the information precludes it from being presented at any other time than in transit. Professional drivers engage in trip planning activities which familiarize them with the regulations associated with different segments of their route. The goal is to remind the drivers without distracting them unnecessarily from the driving task. Therefore, this information will be presented to the driver aurally.

Special Design Considerations: Research done to date regarding the presentation of auditory messages indicates that aural messages should be comprised of a minimum of 4 syllables to provide sufficient linguistic context for comprehension (Reference 2), but limited to 7 to 9 units (Reference 3). Also, for increased intelligibility, Reference 4 suggests that sentences be used instead of isolated words.

Rather than completely processing all of the signs along the roadway, CVO drivers selectively attend to those which are most applicable to their current driving situation. Therefore, it might be worthwhile to allow a driver to selectively filter the sign information which will be presented to them in–vehicle. The ability to filter sign information might help to protect drivers, especially CVO, from the possibility of information overload.

Cross References:

Use of Alerts for ATIS Messages

Timing of Auditory Navigation Information

Presentation of Filtering Sign Information

Trip Status Allocation Design Tool

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

 

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PRESENTATION OF CVO–SPECIFIC CARGO AND VEHICLE MONITORING INFORMATION

Introduction: CVO–specific cargo and vehicle monitoring information refers to more detailed and diverse information than that presented to private drivers. It may include a more precise indication of engine performance. In addition, many commercial vehicles carry sensitive cargo, which require careful monitoring of things like temperature, humidity, and vibration.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Condition of the cargo

Visual or
Visual and Auditory

Vehicle
in Motion

Text description with or without voice

Condition of the trailer

Visual or
Visual and Auditory

Vehicle
in Motion

Text description with or without voice

Precise information regarding vehicle performance

Visual or
Visual and Auditory

Vehicle
in Motion

Text description with or without voice

 

Schematic Example of Presenting Cargo and Vehicle Monitoring Information

Schematic Example of Presenting Cargo and Vehicle Monitoring Information

Important Note: The graphic depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

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 CVO–specific cargo and vehicle monitoring information. It was determined that cargo and vehicle monitoring should be done in transit to allow drivers to monitor for changes which might affect their ability to successfully complete the route or make a scheduled delivery. When determining the appropriate sensory modality, it was determined that visual displays are somewhat more flexible and give the driver greater detail, but lack the ability to grab the attention of a driver. However, when used in combination with an auditory alert or message, visual displays can provide fast response times and detailed information that can be referred to visually when the driver feels it is safe to do so. An auditory message might be used to augment visual information unless, for example, abnormal conditions are present.

Special Design Considerations: Cargo and vehicle monitoring information could be useful for dispatchers and company managers if it is used as an aid in coordinating maintenance and ensuring the timely delivery of undamaged goods. The dispatcher could use this information to arrange for repair services, note recurring problems with specific vehicles, or select alternate routes. However, it is conceivable that drivers may resent the dispatcher's ability to monitor their performance so closely. Unless these systems are introduced while considering the broader issues of driver acceptance, drivers' behavior and use of the system may reduce its potential.

Cross References:

Trip Status Allocation Design Tool

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

 

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ESTIMATED TIME OF ARRIVAL FOR EMERGENCY VEHICLES

Introduction: Estimated time of arrival (ETA) refers to the ability of a system to estimate the time remaining until a vehicle reaches the destination. In this context, ETA is simply the length of the route remaining to be negotiated divided by the average speed expected over the remaining route (e.g., ETA is 3 minutes, 15 seconds). It is common in some domains to add ETA to the current time to express estimated arrival time in clock time (e.g., a commercial aircraft might express their ETA as 7:30 p.m.). Accurate ETA information is critical to the effective deployment of emergency response vehicle fleets.

Design Guidelines**
  • ETA for all vehicles responding to a location should be available continuously to emergency vehicle dispatchers.
  • These ETAs should be updated in near real time, and displayed in a format that supports dispatcher decision making.
  • Display update rates for alphanumerics should be slow enough to allow reading of the individual characters; updates should not be made at a rate faster than 1 Hz.
  • The user should be provided a means to "freeze" the values to allow simultaneous comparison of ETAs for different vehicles.

 

Schematic Example of Presenting Estimated Time of Arrival for Emergency Vehicles

Schematic Example of Presenting Estimated Time of Arrival for Emergency Vehicles

Important Note: The map display depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

Supporting Rationale: Display update rates for alphanumerics should be slow enough to allow reading of the individual characters; updates should not be made at a rate faster than 1 Hz, as recommended in Reference 2. The ability to get emergency response vehicles on–site as quickly as possible is critical to saving lives and property. It is common, therefore, for dispatchers to initially direct multiple vehicles to respond to the same destination. Later, as the sequence of arrivals becomes apparent to the dispatcher, all but the earliest arriver(s) is (are) redirected or recalled. Until being redirected, unnecessary vehicles are not available to respond to other emergencies. Determining order of arrival requires the dispatcher to estimate distances and expected speeds, taking traffic into account, for each emergency vehicle. This is a difficult and error prone task when performed manually.

As described in Reference 1, the use of navigation and guidance systems coupled with real–time traffic information promises both improved estimation of arrival times and reduced workload placed on dispatchers. Providing ETA information to dispatchers will reduce the use of redundant vehicles in responding to emergency situations. This improvement may be manifest as a reduction in the number of vehicles initially dispatched, or in terms of reassigning or recalling dispatched vehicles earlier than can be done when ETA is estimated manually. Improvements in dispatching emergency vehicles are expected to translate into improvements in overall efficiency of emergency services.

Special Design Considerations: The user should be provided a means to "freeze" the values to allow simultaneous comparison of ETAs for different vehicles. Clearly, ETA should be as accurate as possible. In order to accurately estimate arrival times, the computations for emergency response vehicles must take the differences in the operating pattern between these vehicles and those of nonemergency vehicles into account. For example, the ability of emergency vehicles to "run" red lights and stop signs, and to travel the wrong way on one–way streets and divided roads, will result in faster transit times and earlier ETAs than nonemergency vehicles. (The ability to drive the "wrong" way and to drive off–road [e.g., through a park] also have implications for navigation and guidance systems tailored to emergency vehicles.) Additionally, ETA computations should not necessarily assume that the speed of traffic along the route (e.g., "probe" vehicles) is a good estimator of the speed the emergency vehicle will be traveling. Even in heavy urban stop–and–go traffic, an emergency vehicle may be able to travel more rapidly than nonemergency vehicles.

Cross References:

Symbol Versus Text Presentation of ATIS/CVO Messages

Key References:

    1. Clarke, D. L., McCauley, M. E., Sharkey, T. J., Dingus, T. A., & Lee, J. D. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: Comparable systems analysis. Washington, DC: Federal Highway Administration (FHWA –RD–95–197).

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

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

 

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PRESENTATION OF CVO–SPECIFIC REGULATORY ADMINISTRATIVE INFORMATION

Introduction: CVO–specific regulatory administrative information refers to various regulatory administrative requirements, including taxes, licensing, permits, and coordination of the transport of hazardous materials. This function may also be involved with checking the required training programs and other administrative functions required of a CVO company by law.

Design Guidelines*

Information Element

Display Type

Trip Status

Display Format

Allow driver to complete administrative paperwork electronically

Visual

Vehicle in PARK

Text description

Information from dispatcher regarding schedule changes and other pick–up/delivery information

Visual

Vehicle in PARK

Text description

 

Schematic Example of Presenting CVO-Specific Regulatory Administrative Information

Schematic Example of Presenting CVO-Specific Regulatory Administrative Information

Important Note: The graphic depicted above is provided solely to augment this Design Guideline by illustrating general design principles. It may not be suitable for your immediate application without modification.

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 CVO–specific regulatory administrative information. This information should be entered into the system before a trip is begun so that it can be transmitted to the appropriate check stations as the drivers travel the route. Due to the complexity and the amount of information to be entered into the system, it was determined that visual text would be the best display format to use.

Special Design Considerations: Currently, regulatory administration relies on the physical inspection of vehicle, driver, and/or shipment paperwork at the ports of entry and other locations. With ATIS, this would be done electronically using a comparison of information originally provided by the carrier, weight sensors on the roadway, and identification tags on the vehicle. This would remove the necessity for a vehicle to stop at the port of entry to have paperwork examined. The success of this function will depend on the ability of designers to make the system efficient and easy to use. Marketing will also play an important part in the success of this type of system. It will be important for the drivers to view this system as an aid, designed to make their job easier, rather than a way for management or government to check up on them.

Cross References:

Presentation of Filtering Sign Information

Trip Status Allocation Design Tool

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

 

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MODALITY OF ATIS INFORMATION FOR CVO

Introduction: The modality of ATIS information for CVO refers to the use of auditory and/or visual presentation modalities.

Design Guidelines***

Use an auditory presentation mode instead of a visual mode, particularly for simple information under conditions in which the driver must make a rapid response to the information.

 

Effects of ATIS Information Modality on Driver Response Time

Graph Showing the Effects of ATIS Information Modality on Driver Response Time

 

Supporting Rationale: In Reference 1, a low–fidelity, fixed–base driving simulator was used to study the effects of different approaches to ATIS design and levels of driver fatigue on driver performance. ATIS information provided in the study included on–road signage and route guidance information. Both visual and auditory modalities were used to present ATIS information and, in both modes, different levels of information complexity were assessed. Fatigue was manipulated by using both sleep–deprived and non–sleep–deprived experimental subjects. Reaction time was consistently faster to ATIS information presented via the auditory mode than via the visual mode.

Special Design Considerations: In Reference 1, there was a small increase in reaction time in the auditory mode when information complexity increased from medium (speed limit, current speed, engine condition, road signing, navigation map indicating distance to the next intersection) to high (medium condition + current and upcoming street names). There was no such increase in the visual mode. This suggests that the advantages associated with the auditory modality decrease as the complexity of the ATIS information increases.

Cross References:

Sensory Modality for Presenting ATIS/CVO Messages

Key References:

    1. Lee, J. D., Dingus, T. A., Mollenhauer, M. A., & Brown, T. (1996). Development of human factors guidelines for advanced traveler information systems and commercial vehicle operations: CVO driver fatigue and complex in–vehicle systems. Washington, DC: Federal Highway Administration (FHWA–RD–96–151).

 

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FHWA-RD-98-057

 

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