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Cover of Guideline for Incorporating Human Factors in Human Machine Interface
Guideline for Incorporating Human Factors in Human Machine Interface
  • Publication no: AP-G113-26
  • ISBN: 978-1-923617-31-5
  • Published: 19 February 2026

This guideline provides Human Machine Interface (HMI) design guidance for in-vehicle systems, based on best practice, available research evidence and established human factors principles. The aim is to promote the application of human factors to the design of vehicle systems to enhance vehicle safety and reduce road trauma.

Human factors focus on understanding and optimising interactions between humans and systems to enhance performance, safety, health and wellbeing.

The guideline contains 54 HMI design principles, grouped under 14 design criteria that each address a specific design element on in-vehicle systems (device placement, interaction methods and restricted functions).

The guideline is intended to be used by in-vehicle system designers and manufacturers when developing original equipment devices, as well as aftermarket and portable devices. It offers guidance for the safe design of in-vehicle information, communication and entertainment systems, wearable devices that connect wirelessly to the vehicle, advanced driver assistance systems (ADAS) and Level 2 and 3 Automated Driving Systems (ADS). It is applicable to the design of in-vehicle systems for both light and heavy vehicles.

National Driver Distraction Roadmap

Austroads has published the following guidelines to help operationalise early actions, convene stakeholders and commission targeted guidance aligned to the National Driver Distraction Roadmap.

  • Driver Distraction Roadmap Implementation Guide (Austroads 2024) — incorporates an implementation framework, a governance framework, and key elements of a forward work program.
  • Guideline for Driver Distraction Data Collection (Austroads 2026) — establishes a national definition of driver distraction harmonises crash and infringement data collection so jurisdictions can more reliably identify and code distraction.
  • Guideline for Human Factors Integration in Road Transport (Austroads 2026) — helps road transport stakeholders embed Human Factors Integration (HFI) into transport system design and operation.
  • Guideline for Incorporating Human Factors in Human Machine Interface (this Guideline)
    — addresses in‑vehicle interface design so that essential functions can be operated safely and intuitively, with minimal visual and cognitive demand.

The guidance, tools and priorities developed under the Roadmap provide a foundation for others to adopt, extend and embed within their own policies, standards and operational practice.

  • Summary
  • 1. Introduction
    • 1.1 Purpose of the guideline
    • 1.2 Scope
    • 1.3 Background
    • 1.4 Development of the guideline
    • 1.5 How to use this guideline
  • 2. Human Machine Interface Design Guidelines
    • 2.1 General design principles
      • 2.1.1 Principle 1.1: Controls, displays and applications should look and function the way users expect them to, based on their experience with similar systems
        2.1.2 Principle 1.2: A system should be consistent in its layout, controls, sequence of actions and inputs and outputs across all its functions and sub-systems
      • 2.1.3 Principle 1.3: The amount of information the driver must remember when using a system should be minimised
      • 2.1.4 Principle 1.4: Controls and displays that are similar in function or used together should be located near each other and share common design elements (e.g. colour, size, shape)
      • 2.1.5 Principle 1.5: Information that is accessed frequently, or that is safety-critical, should be displayed in a location that facilitates rapid extraction
    • 2.2 Device placement
      • 2.2.1 Principle 2.1: The system should be mounted securely to the vehicle, preferably using the manufacturer’s original mounting or a system-specific, commercially available mounting
      • 2.2.2 Principle 2.2: The system’s display and associated controls should be placed as close as practicable to the driver’s direct line of sight
      • 2.2.3 Principle 2.3: The system should be located in a position that it is easy to reach when driving
    • 2.3 Visual displays
      • 2.3.1 Principle 3.1: The display should be designed and installed to minimise glare and reflections
      • 2.3.2 Principle 3.2: The display should contain colours that are clearly and easily distinguished and convey the urgency of the situation
      • 2.3.3 Principle 3.3: All text and symbols should be of adequate size and font to be clearly readable while the vehicle is in motion
      • 2.3.4 Principle 3.4: The amount and complexity of information the driver must read is minimised when the vehicle is in motion
      • 2.3.5 Principle 3.5: Systems should only require drivers to make a few, short (no more than 2 seconds) glances to the display
      • 2.3.6 Principle 3.6: Head-Up Displays (HUD) should be used to present simple information about critical safety situations in the driver’s forward line of sight
    • 2.4 Auditory interfaces
      • 2.4.1 Principle 4.1: Different tones, signals and messages should be easily distinguishable from each other and other sounds inside and outside of the vehicle
      • 2.4.2 Principle 4.2: Auditory messages should only contain relevant information and be supplemented with visual information where possible
      • 2.4.3 Principle 4.3: The volume of auditory tones and messages should be loud enough to be heard under all driving conditions, but should not startle the driver or mask warnings from within or outside of the vehicle
      • 2.4.4 Principle 4.4: Speech output should be used instead of tones for messages that are not time-critical and require complex and/or precise auditory information
    • 2.5 Haptic interfaces
      • 2.5.1 Principle 5.1: Haptic interface elements should elicit rapid and accurate responses
      • 2.5.2 Principle 5.2: Haptic warnings should be distinctive and clearly distinguishable from normal vehicle vibration and other haptic signals in the vehicle
      • 2.5.3 Principle 5.3: Haptic warnings should provide information regarding the direction of the threat or hazard, where possible
    • 2.6 Manual control inputs
      • 2.6.1 Principle 6.1: Control types, appearance and movement should be appropriate for the task/function that they execute
      • 2.6.2 Principle 6.2: System controls should be easily identifiable and distinguishable from each other
      • 2.6.3 Principle 6.3: Controls should provide appropriate visual, auditory and/or tactile confirmation to the driver confirming when a selection or input has been made
      • 2.6.4 Principle 6.4: System controls should be able to be operated with one hand only, allowing drivers to always keep one hand on the steering wheel
    • 2.7 Voice input
      • 2.7.1 Principle 7.1: The system should be able to recognise naturally spoken language or conversation style and the use of specific verbal commands should be minimised
      • 2.7.2 Principle 7.2: Where specific verbal commands are used, these should be brief, easy to remember and use terminology that is familiar to users
      • 2.7.3 Principle 7.3: Where specific verbal commands are used, these should be semantically and acoustically discriminable
      • 2.7.4 Principle 7.4: There should be a dedicated button to activate and deactivate voice control and auditory and/or visual feedback provided to users, to indicate when they should start and stop speaking
      • 2.7.5 Principle 7.5: Any function that is operated using voice input, should also have an alternative input mode (either direct physical input (button) or touch input)
      • 2.7.6 Principle 7.6: Voice input should not be used for long and/or complex tasks
    • 2.8 System navigation
      • 2.8.1 Principle 8.1: The design, structure and navigation method of system menus should be consistent throughout
      • 2.8.2 Principle 8.2: The most frequently used applications or functions should be the easiest/first to reach
      • 2.8.3 Principle 8.3: Single layer menus should be used where possible, but where systems have hierarchical menus these should be organised so that they have a greater breadth (alternatives) rather than depth (levels)
      • 2.8.4 Principle 8.4: It should be easy for drivers to navigate back and forth across menu levels, return to the start/home or escape a dead end
    • 2.9 Interaction methods
      • 2.9.1 Principle 9.1: The user should be able to control the pace of interaction with the system
      • 2.9.2 Principle 9.2: Interacting with the system should require a minimal number of steps/actions
      • 2.9.3 Principle 9.3: Interaction with the device should be able to be interrupted and resumed by the driver at the point of interruption or at another logical point
    • 2.10 System feedback
      • 2.10.1 Principle 10.1: Information provided by the system should be timely, accurate and clearly understandable
      • 2.10.2 Principle 10.2: Systems should provide suitable notification/warning when new or updated information is available that is directly relevant to the current driving task or system status
      • 2.10.3 Principle 10.3: Where possible, the system should provide real-time cues to nudge/direct driver attention back to the roadway if their eyes have been diverted from the forward roadway for more than 2 seconds
    • 2.11 Lockouts and restricted functions
      • 2.11.1 Principle 11.1: Systems or functions that are complex or impose high workload should be automatically disabled or inaccessible to drivers when the vehicle is in motion (i.e. travelling at a speed above 0 km/h)
      • 2.11.2 Principle 11.2: Where possible, the system should dynamically adjust its behaviour based on current driving demands to reduce the level of workload it imposes on the driver
    • 2.12 Warning design and scheduling
      • 2.12.1 Principle 12.1: Warnings should be prioritised, with the most urgent or safety/time-critical warnings being issued before lower priority messages
      • 2.12.2 Principle 12.2: For high priority or time-critical warnings, simultaneous visual, auditory and/or haptic (multimodal) signals should be used
      • 2.12.3 Principle 12.3: A visual presentation modality should be used for warnings of low priority, high complexity or that are presented frequently
      • 2.12.4 Principle 12.4: The timing of collision avoidance warnings should consider expected driver response time
      • 2.12.5 Principle 12.5: Warnings should provide the driver with directional clues regarding the location of the threat and provide advice about appropriate actions that the driver can take to resolve the situation
    • 2.13 Design of Automated Driving System interfaces
      • 2.13.1 Principle 13.1: Information about system status and mode should be presented clearly and continuously
      • 2.13.2 Principle 13.2: Drivers should clearly understand their roles and responsibilities in relation to the driving task at any given time
      • 2.13.3 Principle 13.3: Automated driving system take-over request warnings should be clear, multimodal and graded
      • 2.13.4 Principle 13.4: The timing of take-over messages should allow sufficient time for drivers to regain situation awareness and take back vehicle control
      • 2.13.5 Principle 13.5: The automated driving system should be designed to optimise driver workload and prevent a loss of situation awareness
    • 2.14 Provision of system information and training for end users
      • 2.14.1 Principle 14.1: Manufacturers and device developers should provide end users with clear and concise information or training on the system’s functionality, operation and limitations
  • 3. Conclusion
  • 4. References
  • Appendix A List of Existing HMI Guidelines Reviewed
Related publications
Guideline for Driver Distraction Data Collection
AP-G114-26
Guideline for Human Factors Integration in Road Transport
AP-G112-26
Driver Distraction Roadmap: Implementation Guide
AP-G103-24
View all related publications
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