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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-95-153
Date: November 1996

Development of Human Factors Guidelines for Advanced Traveler Information Systems and Commercial Vehicle Operations: Literature Review




Guidelines From ATIS/CVO–Related Technical Reports

The following statements have been taken from various technical reports. Those guidelines applicable to an ATIS/CVO guideline document are presented in an outline (list) format. The title and author of the technical report that the information was taken from are cited with an underlined heading.

Human Factors Issues Surrounding the Implementation of In–Vehicle Navigation and Information Systems.

Moffit, Roger, and Cincinelli (1986) stated that color CRT use is accompanied by problems of visibility and discriminability in daylight.

Zwahlen and DeBald (1986) studied the use of cellular phones. They found that dialing long numbers resulted in unacceptable lane deviations.

Improving Motorist Information Systems: Toward a User–Based Motorist Information System for the Puget Sound Area (Haselkorn and Barfield, 1990).

Haselkorn and Barfield made the following recommendations for the categories specified:

Pre–Trip Information. Place a high priority on home delivery of motorist information, particularly information that will impact departure time.

Target home–delivered motorist information for specific types of commuters, based on the driving decision to be impacted.

Reliability of Motorist Information. Include a feedback mechanism in any motorist information system to assess information reliability.

On–Road Information. Place a high priority on improving on–road information delivery mechanisms.

When designing and delivering on–road motorist information, target those commuters who tend to change routes while driving.

Through the use of integrated information systems, coordinate home and on–road messages based on delivery location and motorists' needs for feedback and reinforcement.

Improve on–road message content. Balance the trade–offs between generality and specificity of the message, and between reason and task information.

Keep on–road messages relevant to particular driver decisions, or to feedback and reinforcement of those decisions.

Incorporate the timeliness messages into on–road motorist information.

Integrate on–road delivery mechanisms more closely with real–time gathering of traffic data.

Design rules for CRT displays in vehicles (combined from two reports: Zwahlen et al., 1987; Streeter and Vitello, 1986).

A maximum of two consecutive looks should be required to operate a CRT touch–panel control system.

Two to four seconds (although shorter ranges are best) is the acceptable time range for interrupting the driver's scanning of the road to operate a CRT panel.

HUD's are an alternate display method to be consider since information is displayed directly in the field of view on the windshield.

The placement of the navigational instrument display should maximize the driver's use of near–peripheral vision, so other driving tasks are possible while attending to the instrument.

Navigation information should be presented vocally even though computer–generated graphics are also effective.

Crucial design issues in audio message systems (Michaelis, 1990).

Vocabulary. Drivers should not be alienated by the use of unfamiliar words.

Intonation and Inflections. Synthesized speech needs to be tailored to be intelligible. Strategically placing pauses between words can simulate inflection.

Cues. The speaker should sound sincere, helpful, and friendly, not condescending or threatening.

Training. Drivers should be exposed to synthesized speech prior to using a system in order to get accustomed to it.

Highway advisory radio message guidelines (Dudek and Huchingson, 1986).

A terse message style is better than a verbose style when route information is delivered.

The chunking capacity of the short–term memory for navigational directions is seven words. Drivers have the capacity to remember a maximum of four turns and four street names.

Repetition of auditory route instructions improves recall. Repetition can be achieved by external or internal means.

Using the number of traffic lights as landmarks between turns should be done carefully and should be avoided when flashing lights are present.

The level of detail for a route change should be tailored to the user. Less detail is required for those familiar with the route.

The instruction "you have come too far" is helpful for those that mistakenly change course, yet Streeter et al. (1985) indicated otherwise.

Effects of Variations in Driving Task Attentional Demand on In–car Navigation System Usage (Wierwille, Hulse, Fischer, and Dingus, 1988).

The visual display should be high on the dash, with a minimum viewing angle from a straight ahead position to allow peripheral vision. This peripheral vision would be used for driving while attending to the navigator.

Future In–car Information Systems: Input from Focus Groups (Green and Brand, 1992).

Drivers learned by reading manuals, listening to cassettes, and playing with the systems. Cassette tapes were well–liked, while manuals were noted to have shortcomings.

Drivers wanted advance, early information on failing vehicle systems.

Drivers complained about the operability of entertainment systems. Reach distance, too many controls, and controls that were too small were cited. Illegible labels were also a problem.

Drivers wanted directions for local trips and maps for long trips.

People preferred "left/right" turning directions rather than "north/south" directions.

For long trips, people wanted to know which direction they were heading.

For turns, landmarks were desired in addition to heading direction.

Laboratory Assessment of Driver Route Diversion in Response to In–vehicle Navigation and Motorist Information Systems (Allen, Ziedman, Rosenthal, Torres, and Halati, 1991).

More information about upcoming traffic conditions led to greater compliance to taking alternate routes.

Older drivers were less likely to change route regardless of congestion. Perhaps this was because older drivers were recruited from a retirement home and may have been less confident in their independent abilities as compared to older drivers who live in their own homes.

Human factors design of the TravTek driver interface (Fleishman, et al., 1991).

Limiting of ATIS functions while driving. Given the visual attention demands of driving, researchers permitted only traffic update information and navigational information to be displayed while the vehicle was in gear. These displays were categorized as "drive" functions. When the vehicle's transmission was placed in park, the other features were made available. These features were called the "pre–drive" functions. In addition, only the hard keys on the steering column were engaged during driving. The touchscreen soft keys on the CRT were only operable while the vehicle was in park or at zero speed, at which point touchscreen keys to control the map displays were engaged.

Steering wheel buttons. Buttons mounted on the steering wheel should be used for simple and important "drive" functions.

Map choices. An overview (route) map should be available to drivers to recover from navigation errors. The system allows switching between route and guidance maps from a steering wheel button.

Updating CRT display. An auditory signal should be used to indicate updated visual information in order to reduce operator's vigilance requirements for CRT display monitoring.

Design of the TravTek Auditory Interface (Means, Carpenter, Fleishman, Dingus, Krage, and Szczublewski, 1992).

Minimize "chattering" by avoiding unnecessarily long voice messages.

Minimize "nagging" by limiting voice to high–priority information and make its role a supplement to the visual interface.

Maximize voice intelligibility by:

  • Using a distinctly non–human, pseudo–male voice.
  • Careful correction and smoothing of synthesized words (vs. digital recordings).

Make information timely and useful if conveyed by voice.

Allow the user to control voice functions, such as volume and repeat message, and to choose the types of messages to be enunciated.

Avoid auditory "clutter." Use the voice for the most important messages. Do not use voice for positive feedback since status quo assumes all is well.

How Important is Mobile Communication for a Truck Company? (Huiberts, 1989).

Truck companies prefer visual data over voice as a mode of communication.

There needs to be a way to signal drivers while they are out of the truck (e.g., during loading).

Due to language differences, a printer is desirable for the driver to refer to.


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