DOT HS 812 360December 2016Human Factors Design GuidanceFor Driver-Vehicle Interfaces

DisclaimerThis publication is distributed by the U.S. Department ofTransportation, National Highway Traffic Safety Administration, inthe interest of information exchange. The opinions, findings, andconclusions expressed in this publication are those of the authors andnot necessarily those of the Department of Transportation or theNational Highway Traffic Safety Administration. The United StatesGovernment assumes no liability for its contents or use thereof. Iftrade or manufacturers’ names or products are mentioned, it isbecause they are considered essential to the object of the publicationand should not be construed as an endorsement. The United StatesGovernment does not endorse products or manufacturers.Suggested APA Format Citation:Campbell, J. L., Brown. J. L., Graving, J. S., Richard, C. M., Lichty, M. G., Sanquist, T., & Morgan, J.L. (2016, December). Human factors design guidance for driver-vehicle interfaces (Report No.DOT HS 812 360). Washington, DC: National Highway Traffic Safety Administration.

Form ApprovedOMB No. 0704-0188REPORT DOCUMENTATION PAGE1. AGENCY USE ONLY (Leave blank)2. REPORT DATE3. REPORT TYPE AND DATESCOVEREDDecember 20164. TITLE AND SUBTITLE5. FUNDING NUMBERSHuman Factors Design Guidance for Driver-Vehicle InterfacesContract No. DTN22-11-00236/0016. AUTHORSJohn L. Campbell, James L. Brown. Justin S. Graving, Christian M. Richard,Monica G. Lichty, Thomas Sanquist, L. Paige Bacon, Robert Woods, Hong Li,Diane N. Williams, Justin F. Morgan7. PERFORMING ORGANIZATION NAME AND ADDRESS8. PERFORMING ORGANIZATIONREPORT NUMBERDOT HS 812 3609. SPONSORING/MONITORING AGENCY NAME AND ADDRESS10. SPONSORING/MONITORINGAGENCY REPORT NUMBERBattelle Memorial Institute505 King AvenueColumbus, Ohio 43201-2696. SNational Highway Traffic Safety Administration1200 New Jersey Avenue SE.Washington, DC 2059011. SUPPLEMENTARY NOTESChristian Jerome was NHTSA’s Contracting Officer’s Representative (COR) for this effort.12a. DISTRIBUTION/AVAILABILITY STATEMENTDocument is available to the public from the National Technical Information Servicewww.ntis.gov12b. DISTRIBUTION CODE13. ABSTRACT (Maximum 200 words)This document provides human factors design guidance for driver-vehicle interfaces (DVIs). The guidance provided is based on thefindings of current high-quality research (including both the best-available scientific literature and current research being conductedby agencies of the United States Department of Transportation), as well as basic human factors concepts. The design guidance isprovided as a complementary resource to other documents and resources, as well as an augment to industry research and existingguidance from the National Highway Traffic Safety Administration. The information in this document may be useful to researchers,designers, and original equipment manufacturers and Tier-1 suppliers seeking to ensure the compatibility of DVIs with driverlimitations and capabilities.14. SUBJECT TERMS15. NUMBER OF PAGESDriver Vehicle Interface, DVI, Crash Warnings, Driver Performance; Heavy Vehicle26016. PRICE CODE17. SECURITY CLASSIFICATION OFREPORTUnclassified18. SECURITY CLASSIFICATION OFTHIS PAGEUnclassifiedi19. SECURITYCLASSIFICATIONOF ABSTRACT20. LIMITATION OFABSTRACT

Table of ContentsChapter 1. Introduction . 1-1Background . 1-1Scope . 1-2Objectives . 1-2Organization of this Document . 1-2Chapter 2. How to Use This Document . 2-1Two-Page Format. 2-1The Left-Hand Page . 2-1The Right-Hand Page . 2-2Use of Acronyms . 2-3Chapter 3. General DVI Considerations . 3-1Distraction . 3-2General Workload Considerations . 3-4Workload from Secondary Tasks . 3-6Providing Drivers With Information on System Function and System Messages. 3-8Developing Driver Training Material. 3-10Chapter 4. Design Guidance for Safety Messages . 4-1Multimodal Warning Messages. 4-4Warning Stages . 4-6Providing Forward Collision Warnings That Accommodate Driver BrakeReaction Time . 4-8Using Coverage Zones to Provide Lane Change Information . 4-10Chapter 5. Message Characteristics . 5-1Message Complexity . 5-4Selection of Sensory Modality . 5-6Chapter 6. Visual Interfaces. 6-1Visual Display Type for Safety-Related Messages . 6-2Locating a Visual Display . 6-4Using Color . 6-6Selecting Character Height for Icons and Text . 6-8Characteristics of Legible Text . 6-10Temporal Characteristics of Visual Displays . 6-12Display Glare . 6-14Head-up Displays . 6-16Chapter 7. Auditory Interfaces . 7-1Auditory Display Type. 7-2Perceived Urgency of Auditory Warnings . 7-4Perceived Annoyance of Auditory Warnings . 7-6Loudness of Auditory Warning Signals . 7-8Distinctiveness of Warning Messages . 7-10ii

Using Localization Cues to Indicate Direction.7-12Presenting Warnings Using Speech Messages .7-14Chapter 8. Haptic Interfaces .8-1Selecting a Haptic Display.8-2General Characteristics for Haptic Displays .8-4Improving Distinctiveness of Haptic Displays .8-6Accommodating for Vibrotactile Sensitivity Across the Body .8-8Generating a Detectable Signal in a Vibrotactile Seat .8-10Presenting Spatial Information Using a Vibrotactile Seat .8-12Chapter 9. Driver Inputs.9-1General Guidance for Driver-DVI Interactions .9-2Control Placement.9-4Selecting Physical Control Type .9-6Control-movement Compatibility .9-8Control Coding .9-10Labels for Controls .9-12Voice Recognition Inputs.9-14Chapter 10. System Integration.10-1Prioritizing Messages Presented to Drivers .10-2Using “Master” Warnings in Integrated Warning Systems .10-4Overview of the HFCV Integration Architecture .10-6Chapter 11. Application of Human Factors Design Guidance toHeavy Vehicle DVIs .11-1Design Considerations for Warning Signals in Heavy Vehicles .11-2Selection of Sensory Modality for Heavy Vehicle Warnings.11-4Design Guidance for Visual Displays in Heavy Vehicles .11-6Visual Display Location in Heavy Vehicles .11-8Design Guidance for Auditory Displays in Heavy Vehicles .11-10Design Guidance for Haptic Displays in Heavy Vehicles .11-12Driver Controls for Collision Warning Systems in Heavy Vehicles .11-14General DVI Considerations for Heavy Vehicles .11-16Chapter 12. Tutorials .12-1Tutorial 1: Procedures for Assessing Driver Performance: Visual DemandMeasurements.12-2Tutorial 2: Priority Order Index Look-Up Table for Message Prioritization .12-19Tutorial 3: Preliminary HFCV Integration Architecture .12-21Tutorial 4: Heavy Vehicle Characteristics and Driving Environment Relevant toDVI Design .12-56iii

Chapter 13. Glossary . 13-1Chapter 14. Index . 14-1Chapter 15. Abbreviations . 15-1Chapter 16. Equations. 16-1Chapter 17. Relevant Documents From the United States Department ofTransportation, SAE International, and InternationalOrganization for Standardization. 17-1Chapter 18. References. 18-1iv

INTRODUCTIONDVI DESIGN GUIDANCEChapter 1. IntroductionBackgroundConsiderable progress has been made toward reducing the incidence of property loss, injuries, andfatalities on the Nation’s highways. However, motor vehicle crashes continue to impose a heavytoll upon road users. The National Highway Traffic Safety Administration reports that in 2012there were approximately 5,615,000 police-reported motor vehicle crashes resulting inapproximately 23,000 people killed (with a fatality rate of 1.13 fatalities per 100 million vehiclemiles traveled) and approximately 2.1 million injured (NHTSA, 2014).A number of active safety systems exist or are in development that may address these crashes.Technologies such as forward collision warning (FCW) are being implemented in an increasinglylarge number of new vehicles. Research from the United States Department of Transportation andindustry examining such technologies is helping to develop an information backbone for thesurface transportation system that will support applications to enhance safety, mobility, andsustainability. However, these promising applications, no matter the source of information thatcauses them to activate, present a unique set of challenges for designers of driver-vehicleinterfaces (DVIs).These advanced safety technologies produce a large amount of information. Sometimes, theinformation may be complex (e.g., warning of a vehicle in a blind spot prior to a lane change, orproviding notification of an upcoming hazard). In some cases, this complex information may needto be provided to, comprehended, and rapidly acted upon by the driver to avoid a collision. Thus,ensuring that the DVI enables drivers to quickly and easily access needed information is of greatimportance with respect to driver performance.The purpose of this document is to provide Human Factors design guidance, based on the bestavailable research and established Human Factors concepts, for DVIs. Note that this document isnot meant to serve as a standard. Resources such as Federal Motor Vehicle Safety Standards(FMVSS), SAE and ISO standards, and the Visual-Manual NHTSA Driver Distraction Guidelinesfor In-Vehicle Electronic Devices (NHTSA, 2013) exist that provide design guidance for DVIs.Instead, this document it is meant to serve as a complementary resource for original equipmentmanufacturers (OEMs), Tier-1 suppliers, and the automotive research community in designingDVIs that enable rapid, consistent, and reliable communication between the vehicle and driver.Design Guidance DevelopmentThis human-centric design guidance for the DVIs is intended to provide a more in-depthunderstanding of driver limitations and capabilities for designers. The developers of thisinformation have focused on providing a clear, relevant, and easy-to-use reference of humanfactors data for DVI design and operation. The development team has worked cooperatively withother researchers in order to ensure that relevant research and suggestions are integrated into thedocument. Overall, the DVI design guidance is intended to: Be concise, clear, and easy to use.Include graphics-based design tools and examples that can be used, in particular, bydesigners who lack specific training or knowledge regarding human factors issues andpractices.1-1

DVI DESIGN GUIDANCE INTRODUCTIONInclude discussions of critical design issues and special design considerations when, forexample, design trade-offs must be made or design constraints exist.Serve as a repository for relevant standards and guidelines.Support increased awareness and knowledge of relevant standards, guidelines, humanfactors concepts, and user characteristics among DVI developers and designers.Automotive DVI research in general has typically focused on the design of safety system DVIs.Therefore, the available research cited within this document is primarily drawn from safetyresearch. However, the basic design guidance that this document provides may also help informthe design of non-safety related DVIs (i.e., infotainment and driver convenience systems).Additionally, this document provides information from recent and on-going research in theemerging field of vehicle-to-vehicle (V2V) technology. Due to the variety of data sources used inthis document, users may be uncertain regarding the applicability of individual data sources tosafety‐related versus non‐safety- related DVI questions. In general, when considering theapplicability of individual design topics to a specific DVI design question, users of this documentshould carefully consider the DVI question or issue they are addressing relative to thecharacteristics (e.g., objectives, research and analytical methods, limitations, etc.) of the originaldata sources cited, our syntheses of and conclusions regarding these data sources.While DVI design information can be a valuable tool and resource for designers, it is not withoutlimitations. Many factors must be considered, and tradeoffs examined, prior to finalizing a DVIdesign. Some of these factors include regulation and industry or international standards. This DVIdesign guidance is intended to augment—not replace—the judgment and experience of developersas they design DVIs in this environment.ScopeThis document provides goals and guidance for the design and development of DVIs, for bothlight- and heavy-vehicles, based on current knowledge of driver capabilities and limitations.ObjectivesThe Human Factors Design Guidance for Driver-Vehicle Interfaces document providesinformation on topics based on the best-available research and literature. It also includesinformation on a number of topics based on knowledge gained from recent and on-going NHTSAsponsored research.Organization of this DocumentBeyond this introductory chapter, this document consists of a series of chapters containing DVIdesign guidance. Each chapter contains a set of subtopics relevant to a specific designcharacteristic or element. Chapter 2 provides an overview of the format and content of thesedesign-specific chapter topics (Chapters 3 through 11). Following the design chapters are a set ofreference chapters with supplemental information that may be useful for either a specific topic orfor DVI design in general. This supplemental material (Chapters 12 to 18) includes tutorials, aglossary, an index, lists of abbreviations and equations used in the document, a list of additionalstandards and other documents related to DVI design, and a complete reference list of articles andreports used to develop the design guidance and tutorials.1-2

HOW TO USE THIS DOCUMENTDVI DESIGN GUIDANCEChapter 2. How to Use This DocumentTwo-Page FormatIn this document a consistent two-page format is used to present the individual human factorstopics provided in Chapters 3 to 10. On each page the chapter title is indicated by centered, boldtype within the header. As described in more detail below, the left-hand page presents the title ofthe topic; an introduction and overview of the topic; a high-level design goal; design guidance; agraphic, table, or figure that augments the text information; and the rating associated with thetopic. The right-hand page provides the more detailed supporting rationale for the topic, as well asspecial design considerations, cross-references to related topics, and a list of references. A sampletopic, with key features highlighted, is shown in Figure 2-1; a detailed description of thepresentation format of the topics follows.Figure 2-1. Topic format used in this document.The Left-Hand PageThe topic title is indicated by centered, bold type at the top of the left-hand page.IntroductionThis subsection briefly defines the topic and provides an overview of or background for the topicarea.Design GoalThis subsection provides the high-level functional driver-vehicle interface implementationobjective for the topic. This design goal specifies an objective with regard to driver responses oractivities that the driver-vehicle interface design may support. The objective of this section is to2-1

DVI DESIGN GUIDANCEHOW TO USE THIS DOCUMENTprovide a goal without indicating the specific ways in which the design goal must be met. Sincethere may be a number of design approaches that could achieve the functional outcomes specifiedby the design goal, this level of guidance provides system and application developers withflexibility for meeting the goal with alternative design and implementation approaches.Design GuidanceThis subsection provides the best-available design information from the literature, includingspecific, quantitative design parameter values, if available, that can be incorporated into a drivervehicle interface that satisfies the design goal. This represents the most directly “actionable”information presented in each topic, although the level of specificity may vary depending on theavailable research. A key goal within this subsection is to present the design guidance clearly andsuccinctly, with a minimal amount of clutter. Where individual information in this subsectionreflects a direct quote or has a direct source, the source is cited. Often, information presented herereflects a synthesis of the findings, conclusions, or results from several sources, not just a singlesource. Also, it may reflect the judgement of the authors, after the reviews and analyses of therelevant data sources have been completed. In general, the Discussion subsection (discussedbelow) is intended to provide users of this document with support and rationale for the designguidance provided.Figure, Table, or GraphicThis subsection provides a figure, table, or graphic to augment the design topic. This figure, table,or graphic might take many forms, including: a drawing depicting a generic application of designguidance or a particular design issue, a flowchart of measurement procedures for the design topic,a table that summarizes the design topic, or schematic examples of particular visual warnings. Thefigure, table, or graphic will provide at-a-glance information to support the use of the designinformation.The Right-Hand PageDiscussionThis subsection briefly summarizes the rationale behind the choice of the design guidanceprovided. The discussion can take many forms, including a brief review of applicable empiricalstudies, references to traditional design practice, or an analysis of relevant information. Thediscussion is presented primarily to help designers understand the design guidance and to helpthem explain or justify the information to others involved in developing a particular system orapplication.Design IssuesThis subsection presents special design considerations, design cases (e.g., older drivercapabilities), or other concerns that may impact the effectiveness of the driver-vehicle interfacedesign. Design issues are only included on an as-available, as-needed basis; not all topics include adesign issue subsection.Cross ReferencesThis subsection lists the titles and page numbers of other topics within this document that areparticularly relevant to the current topic.2-2

HOW TO USE THIS DOCUMENTDVI DESIGN GUIDANCETopic ReferencesThis subsection lists the references associated with the formulation of the design topic. Each ofthese references will already have been noted within the text of the design topic and assigned areference number. It provides a quick way for designers to identify the source of the designinformation and for the authors to source the information.Use of AcronymsAll acronyms and abbreviations are listed in alphabetical order in Chapter 15.2-3


GENERAL DVI CONSIDERATIONSDVI DESIGN GUIDANCEChapter 3. General DVI ConsiderationsThis chapter provides design guidance that address high-level design considerations related todriver needs and abilities. These include topics such as driver customization of system elements,driver distraction, driver workload considerations, and driver training. Unlike most other chapters,Chapter 3 focuses on more general information about these topics, rather than specific designrecommendations. The objective is to discuss considerations for system design; the way in whichthese considerations will apply depends upon the specific system or application.Topics addressed in this chapter: DistractionGeneral Workload ConsiderationsWorkload From Secondary TasksProviding Drivers With Information on System Function and System MessagesDeveloping Driver Training Material3-1

DVI DESIGN GUIDANCEGENERAL DVI CONSIDERATIONSDistractionIntroductionDriver distraction is a diversion away from activities critical for safe driving toward a competing activity [1]. In somescenarios, DVIs may contribute to distraction. This topic provides a list of the principles covered in the NHTSAVisual-Manual Driver Distraction Guidelines for In-Vehicle Electronic Devices [2]. The NHTSA guidelines should beconsidered a critical source of DVI design information relevant to distraction. NHTSA has published driver distractionguidelines that provide requirements for in-vehicle displays and applications. The current topic does not providespecific design guidance, but rather provides a list of where to find recommendations on specific topics in the NHTSAVisual-Manual Guidelines. More information on this topic is also available in the Alliance of AutomobileManufacturers AutoAlliance Statement of Principles [3].Design Goal: Design in-vehicle tasks and messages that do not divert attention from activities critical for safedriving.Design GuidanceThe table below lists topics covered by the NHTSA Visual-Manual Guidelines that are related to distraction and invehicle systems.Recommendation/Guideline Topic fromAutoAlliance Statement of Principles [3]Topic CoveredSection in VisualManual Guidelines [2]No Obstruction of ViewDevice location in relation to driver.V. AEasy to See and ReachDriver access to a device.V. BMaximum Display Downward AngleDevice location in relation to driver.V. CLateral Position of Visual DisplaysDevice location in relation to driver.V. DMaximum Size of Displayed Textual InformationSize of visually presented text.V. EPer Se Lock OutsDevice usage while driving.V. FAcceptable Test-Based Lock Out of TasksTasks performed while driving.V. GSound LevelSound level of a device.V. HSingle-Handed OperationDriver control of the vehicle.V. IInterruptibilityDriver interaction with the device.V. JDevice Response TimeFeedback provided to the driver by the device.V. KDisablementPresentation of non-safety-related information tothe driver.V. LDistinguish Tasks or Functions Not Intended forUse While DrivingDriver access to devices while driving.Device StatusPresentation of system status information.Visual Task CompletionDriver interaction with the device.-Driving Relevant InformationInformation presented to the driver.-Speech-Based Communication SystemsDriver interaction with the device.-Pace of Interaction with DeviceDriver interaction with the device.-3-2V. MV. N

GENERAL DVI CONSIDERATIONSDVI DESIGN GUIDANCEDiscussionDriver distraction can contribute to motor vehicle crashes when a driver’s attention is diverted away from the drivingtask at a time when there is an unexpected hazard or change in the driving situation (e.g., lead vehicle braking, apedestrian crossing the road, etc.). Distraction may also be associated with lapse of vehicle control, resulting inunintended speed changes or allowing the vehicle to drift outside of the lane boundaries [4]. This diversion ofattention away from the driving task can be caused by a secondary task that shares the same resources that are neededfor safe driving. The greater the extent to which an action shares the same resources with a driving activity, the higherthe degree of incompatibility between that action and driving, and the higher is the expected degree of distractioninduced by performance of that action while driving [1]. While a driver’s attention should not be diverted away fromactivities critical for safe driving, there are safety-related instances in which redirecting attention is beneficial. Forexample, if a driver is checking a blind spot to make a lane change while a leading vehicle suddenly brakes, a forwardcrash warning will draw the driver’s attention away from the lane change task. In this case, the redirection of attentionto the more safety-critical event is appropriate.Secondary tasks are numerous and many may benefit drivers in some way (e.g., inputting a destination into anavigation system, receiving traffic information updates, etc.). Some drivers may become accustomed to per

This human-centric design guidance for the DVIs is intended to provide a more in-depth understanding of driver limitations and capabilities for designers. The developers of this information have focused on providing a clear, relevant, and easy-to-use reference of human fa