Transport Canada Guidelines to Limit Distraction from Visual Displays in Vehicles

Transport Canada created these guidelines to help minimize distraction from interactions with visual displays in vehicles. This report recommends how to safely design, install and use in-vehicle visual displays.

On this page

• Motivation for these guidelines
• Development of these guidelines
• Scope and intended use
• Visual displays: system function, content and format
• Visual displays: original equipment and portable devices
• Recommended guidelines for visual displays
• References
• Annex A: Visual display distraction checklist
• Annex B: Definitions
• Annex C: Rationale and supporting evidence

Motivation for these guidelines

Distracted driving puts the safety of drivers, passengers and other road users, including pedestrians and cyclists, at risk (US National Center for Statistics and Analysis, 2017). Distraction happens when a driver’s attention is taken away from driving because they are focused on something else (US-EU Bilateral ITS Task Force, 2010).

Driver distraction is still a primary contributing factor in motor vehicle crashes. There are concerns that distracted driving is increasing due to the various technologies in vehicles, which present more types and amounts of information to drivers than before. Canadian data for 2016 show that 21% of fatalities and 27% of serious injuries involved some form of distracted driving, which is notably higher than a decade earlier, at 16% and 22% respectively (Transport Canada, 2018). There is a pressing need to limit distraction in vehicles.

In September 2013, a catastrophic crash happened between an OC Transpo city passenger bus and a VIA Rail train in Ottawa, Ontario. The Transportation Safety Board of Canada investigated this crash (R13T0192) and determined that driver distraction was one of the contributing factors (Transportation Safety Board, 2013). Based on the results of their investigation, they made recommendation R15-01, to “…develop comprehensive guidelines for the installation and use of in-vehicle video monitor displays to reduce the risk of driver distraction” (p. 180). This TSB recommendation, and evidence from research, collision data and technology trends, were factors in Transport Canada’s development of these distraction guidelines.

Devices used by drivers should be safe and compatible with driving. Drivers should use devices in ways that minimize distraction. If that is not possible, the devices should not be available for use while driving. A driver’s primary task is safe control of their vehicle. Naturalistic driving studies show considerable evidence that visual distractions are serious safety problems (e.g., Klauer, Guo, Simons-Morton, Ouimet, Lee & Dingus, 2014; Klauer, Guo, Sudweeks, & Dingus, 2010).  It should not be possible to do non-driving visual tasks, such as reading text messages, while driving.

Development of these guidelines

As part of a contract with Transport Canada, the Virginia Tech Transportation Institute (VTTI) team conducted a literature review to identify existing guidelines and best practices, the latest research on distraction, safety and crash-avoidance applications, and distraction countermeasures related to visual displays.

The VTTI review included:

• display location and position
• size
• viewing angle
• resolution
• glare and night modes
• design
• content displayed (e.g., maps and other dynamic and static visual information, real-time video and other video information)

The review also covered international approaches and research to determine the best-available human factors information on driver distraction in passenger vehicles, trucks, motor coaches and transit buses. The results are based on empirical research along with industry-accepted standards and guidelines (ISO, SAE). The National Highway Traffic Safety Administration (NHTSA) distraction guidelines and Transport Canada research provided a foundation for this work.

Based on their review and assessment of this material, the VTTI team produced a set of recommendations for the design, installation and use of in-vehicle displays. Their report was the basis for these  distraction guidelines.

We have provided links to the full report authored by VTTI and supporting documentation in the list of references (Hickman, Camden, Klauer, & Hanowski, 2017). In addition, Annex A is a checklist for technical experts to use as a tool to evaluate visual displays (for original equipment as well as devices drivers bring into the vehicle).

Scope and intended use

The underlying premise for these guidelines is that we need to fully consider what contributes to distraction. This means examining the device or system the driver is using, but also how the driver interacts with that device, the task they are doing, the duration of the interaction and the context of the device’s use. We should account for all of this when developing an effective approach to limit distraction.

Scope

These guidelines apply to visual displays that drivers may use while their vehicle is in motion. In some instances, the guidelines recommend that interactions be locked out entirely while the vehicle is moving. In other cases it recommends that interactions and tasks be controlled or modified in a way that reduces distraction. Essential and commonly used controls and displays should be directly accessible to the driver.

These recommendations apply to visual displays in passenger vehicles, trucks, motor coaches and transit buses. They apply to all displays visible to the driver, whether original equipment (i.e., displays built into the vehicle), permanently installed aftermarket devices, or devices that drivers bring into the vehicle.

These displays have information and communication functionality including, but not limited to:

• heating, ventilation and air conditioning (HVAC)
• navigation
• entertainment
• social media
• passenger monitoring cameras
• work-related scheduling

The visual displays offer various forms of content, such as:

• images (graphics or photos)
• scrolling information
• video, which includes pre-recorded images, live video images and Internet broadcasts

These guidelines are intended to limit distraction. They are not a substitute for requirements in regulations or standards. The guidelines in this document are voluntary. Transport Canada encourages vehicle and electronics manufacturers to design devices that are compatible with safe driving, and to follow current safety guidelines and best practices. As part of its research program, Transport Canada monitors the safety of technologies, including both original equipment and those that drivers bring in the vehicle.

What is out of scope

These recommendations do not apply to visual displays for back-up cameras and blind spot cameras, which are meant to help with safe driving. Back-up camera images can be displayed while a vehicle is in reverse. Blind spot images can be used to help drivers maneuver. Blind spot displays should be located in the general direction drivers look when using side and rearview mirrors.

Visual warnings in vehicles (e.g., seatbelt reminders, flashing lights from a collision warning system) are not in the scope of this report, as they are intended to support safer driving. 

These guidelines also doesn’t address distraction from devices such as heads up displays (HUDs) and optical head-mounted displays (OHMDs). This does not mean they should be considered safe. Visual attention to these devices is difficult to determine and there is limited evidence on how they affect distraction.

The guidelines in this document are essential, but they won’t fully address the issue of driver distraction. We need complementary approaches such as driver education and training, legislation, regulations and employer policies. These approaches are also not in scope.

Intended use

This document provides background information, research evidence, guidelines and a summary of best practices. We intend for the following groups to use these recommendations:

• designers and manufacturers of motor vehicles and aftermarket devices
• automotive suppliers
• consumer electronics device manufacturers
• automotive applications developers

This report may also help to support drivers and fleet managers select vehicles and devices with less distracting visual displays. Use the checklist in Annex A when you select vehicles, assess current vehicles or consider adding technologies to existing vehicles.

Visual displays: system function, content and format

Visual displays can be very useful to drivers because they are well suited to presenting complex information quickly. They make information available in a continuous format that drivers can consult when they need it. Auditory information, in comparison, is usually available only briefly and is not available for future reference.

Visual displays can show information for both driving-related and non-driving related purposes. Table 1 shows examples of driving-related and non-driving-related tasks and devices. These examples are representative but not exhaustive.

Content and presentation format

The information on visual displays can be presented in many ways, including but not limited to:

• still graphical or photographic images
• still text, lists, menus, labels
• moving information (images and/or text)
• video content, which includes pre-recorded images, live images, closed-circuit television, and television or Internet broadcasts

Table 1: Examples of driving-related and non-driving-related information

Driving-related tasks and devices
Trip and Vehicle Information	Navigation systems: Maps, locations, etc. Destination entry Route following Trip computer Heating, ventilation and air conditioning (HVAC) Fuel economy displays
Non-driving-related tasks and devices
Communications	Caller identification Incoming call management Making and ending phone calls Conference calls Two-way radio communication Paging Address book Reminders Text-based communications Social media messaging or posting
Entertainment	Radio (AM, FM, satellite, etc.) Pre-recorded music players (all formats) Television Video displays Advertising Internet browsing News Directory services
Work-related functions	Scheduling Information display Work management Passenger monitoring cameras

Although using these types of displays can lead to distraction, following guidelines on their safe use (or non-use) can limit adverse effects.

Ideally, designers and manufacturers will use these approaches to limit distraction from the start and apply them throughout the product design process. Tasks and their associated human-machine interfaces (i.e., displays and controls) should be designed so they don’t interfere with the driver’s ability to safely perform the dynamic driving task (i.e., object and event detection and response, and lateral and longitudinal vehicle control). Tasks that do interfere should not be accessible to the driver while the vehicle is in motion. Distracting tasks should be locked out while drivers are operating the vehicle, or be modified to make them safer.

Note that “while driving” includes times when a driver is stopped in traffic or waiting at an intersection. Tasks that are not safe while driving should only be done when the vehicle is stopped safely (e.g., in “park”, parking brake engaged, transit vehicle at a designated stop).

Visual displays: original equipment and portable devices

The visual displays addressed in these guidelines have two basic types:

• Displays provided by the original equipment manufacturer (OEM), which come with the vehicle at the time of purchase. These are called “original equipment.”
• The second category, “portable devices”, are systems purchased separately from the vehicle, but brought into the vehicle for use while driving. This category includes devices for temporary in-vehicle use (e.g., smart phones, navigation systems; sometimes called “nomad devices”) and aftermarket devices (e.g., visual display screens) for more permanent use. Vehicle owners can install aftermarket devices permanently or semi-permanently, for example, in the centre stack console.

Portable devices may have visual displays that are not designed for use while driving. They may be designed instead for specific purposes or have multiple uses (e.g., smart phones which are used for communication, information searching, navigation, etc.). In these cases the tasks, and their displays and controls, are often designed to be the user’s only activity. They are not intended to be used with driving.

OEM visual displays, in contrast, are intended to be used while driving. They have likely been designed according to accepted distraction guidelines. Such displays normally have large, centrally positioned screens that are easier to read and use.

NHTSA (2016) recommends two approaches for portable devices brought into the vehicle for temporary use. They recommend that portable devices be paired (i.e., connected) with the vehicle. This way the driver interacts with them using OEM-designed and dedicated displays and controls while driving. In this case, the OEM interface replaces the interface on the portable device for in-vehicle use. NHTSA also recommends that systems which are not paired be designed with simplified “driver mode” interfaces more suitable for use while driving. Transport Canada supports these recommendations.

Recommended guidelines for visual displays

This section discusses recommended device integration and lock outs. Table 2 describes the four areas and issues of concern for visual displays: physical location, content of visual displays, visual interaction and task interaction.

Recommendations in the table are the basis of the checklist in Annex A.

Annex B defines terms to help you use the checklist. Annex C lists the rationale and supporting evidence underlying the recommendations.

Device integration

Portable aftermarket devices meant to stay in the vehicle should be installed according to manufacturer instructions. If a portable device is brought into the vehicle for temporary use, it should be securely mounted.

Device pairing with an OEM interface: This is the preferred way to use a portable device while driving. If the driver is using a smart phone or other portable device, it should be paired with the vehicle so it uses the OEM vehicle visual display interface. The OEM interface should be designed so it is easy to use while driving. Drivers should be able to easily pair their portable device with an OEM interface.

Unpaired portable devices: Portable devices should have a “driver mode,” for drivers to use where device pairing isn’t available or if they choose not to pair the device. Driver mode is an alternate, simplified interface on a portable device, designed for use while driving. Driver mode may be activated automatically when the device is plugged into the vehicle or be activated manually by the driver. Automatic activation is best since it happens by default and does not require the driver to “opt in” for each use.

Visual displays on portable devices should follow the same guidelines as original equipment manufacturer (OEM) devices with visual displays. When in driver mode, the portable device should lock out any visual-manual secondary tasks that do not meet the accepted guidelines (NHTSA, 2016).

Lock outs

Certain functions, tasks and interactions are too distracting for the driver and should not be done while driving. This applies to both OEM interfaces (including devices paired with them) and driver mode interfaces on portable devices. The following are recommended for lock out. They should always be inaccessible while driving (NHTSA, 2013; NHTSA, 2016):

1. Device functions and tasks not intended to be used by a driver while driving
2. Manual text entry by the driver for the purpose of activities such as navigation destination entry, text-based messaging, other forms of communication, or Internet browsing
3. Displaying (or permitting the display of) video including, but not limited to, video-based entertainment and video-based communications including video phoning and videoconferencing
4. Displaying certain graphical or photographic images
5. Displaying automatically scrolling text
6. Displaying text for reading from books, periodical publications, web page content, etc.

The following table provides a summary of recommendations to reduce distraction from visual displays while driving. A checklist based on the content in Table 2 is provided in Annex A.

Table 2: Summary of recommendations

	Visual display guideline recommendations
1. Physical location	1.1 The location of the visual display should not interfere with the driver's view of the road or any of the existing controls and displays. 1.2 The display should be positioned in the forward view as close as possible to road centre, in line with the driver's forward view without obstruction.
2. Content of visual displays	Visual displays that are not to be used by the driver should be locked out so that the driver cannot see their content while the vehicle is in motion. 2.1 Video content and/or moving images should not be displayed while driving (e.g., live or prerecorded video-based communications, entertainment, advertising, etc.). Exceptions: content from backing cameras, blind spot cameras and navigation systems. 2.2 Images that are displayed should be relevant to driving (e.g., for navigation) or to help the driver make a selection, as in the case of an infotainment system, for example. 2.3 Displayed text should be relevant to driving. Text not relevant to driving should not be displayed (e.g., books, web-based content, social media content, text-based advertising and marketing, text-based messages, correspondence, etc.). 2.4 Automatically scrolling text should not be presented.
3. Visual interaction	The visual interfaces should be designed so that the driver can complete the task with brief, sequential glances to minimize impact on driving. 3.1 Drivers should be able to complete a given task with a single glance or a series of individual glances each with a duration of 2 seconds or less. 3.2 The total glance time away from the forward view to complete a task should be less than 12 seconds.
4. Task interaction	4.1 At least one hand should remain on the steering wheel during interactions with the system or display. 4.2 The driver should not be able to enter text manually for the purpose of text-based messaging, other communication or internet browsing. 4.3 The system should provide feedback (i.e., confirmation of the driver input). 4.2 Tasks should be easy to interrupt and resume.

References

American Public Transportation Association. (2009). Reducing agency-controlled distractions while operating a vehicle on agency time(Report No. APTA BTS-BS-RP-006-09). Washington, DC: Author.

Burns, P., Harbluk, J., Foley, J.P., & Angell, L. (2010). The Importance of task duration and related measures in assessing the distraction potential of in-vehicle tasks. Second International Conference on Automotive User Interfaces and Interactive Vehicular Applications (Automotive UI 2010), November 11-12, 2010, Pittsburgh, Pennsylvania, USA.

Campbell, J. L., Brown. J. L., Graving, J. S., Richard, C. M., Lichty, M. G., Sanquist, T., & Morgan, J. L. (2016). Human factors design guidance for driver-vehicle interfaces(Report No. DOT HS 812 360). Washington, DC: National Highway Traffic Safety Administration.

European Union. (2008). Commission recommendation on safe and efficient in-vehicle information and communication systems: Update of the European Statement of Principles on human-machine interface. Brussels, Belgium: Author.

Green, P., Levison, W., Paelke, G., & Serafin, C. (1995). Preliminary human factors design guidelines for driver information systems: Final report (Report No. FHWA-RD-94-087). Washington, DC: Federal Highway Administration.

Hickman, J.S., Camden, M.C., Klauer, S.G., & Hanowski, R.J. (2017). Guidelines on Limiting Distraction from Visual Displays (VDs) in Vehicles. Contract Report for Transport Canada. T8080-160051.

International Organization for Standardization. (2011). 16121-2:2011(E): Road vehicles – Ergonomic requirements for the driver’s workplace in line-service buses: Part 2: Visibility. Geneva, Switzerland: Author.

International Organization for Standardization. (2011). 16121-3:2011(E): Road vehicles – Ergonomic requirements for the driver’s workplace in line-service buses: Part 3: Information devices and controls. Geneva, Switzerland: Author.

Japan Automobile Manufacturers Association. (2004). Guideline for in-vehicle display systems – Version 3.0. Tokyo, Japan: Author.

Klauer, S. G., Dingus, T. A., Neale, V. L., Sudweeks, J. D., & Ramsey, D. J. (2006). The impact of driver inattention on near-crash/crash risk: An analysis using the 100-Car Naturalistic Driving Study data. Washington, DC: National Highway Traffic Safety Administration, USDOT.

Klauer, S. G., Guo, F., Simons-Morton, B. G., Ouimet, M. C., Lee, S. E., & Dingus, T. A. (2014). Distracted driving and risk of road crashes among novice and experienced drivers. New England Journal of Medicine,370, 54–59.

Klauer, S. G., Guo, F., Sudweeks, J. D., & Dingus, T. A. (2010). An analysis of driver inattention using a case-crossover approach on 100-Car data: Final report. Washington, DC: National Highway Traffic Safety Administration.

National Highway Traffic Safety Administration. (2013). Visual-manual NHTSA driver distraction guidelines for in-vehicle electronic devices.

National Highway Traffic Safety Administration. (2016). Visual-manual NHTSA driver distraction guidelines for portable and aftermarket devices.

Ross, T., Midtland, K., Fuchs, M., Pauzie, A., Engert, A., Duncan, B., & May, A. (1996). HARDIE design guidelines handbook: Human factors guidelines for information presentation by ATT systems. Commission of the European Communities R&D Programme.

Stevens, A., Quimby, A., Board, A., Kersloot, T., & Burns, P. (2002). Design Guidelines for Safety of In-Vehicle Information System. Wokingham, Berkshire United Kingdom: Transportation Research Laboratory.

Transport Canada. (2018). Road Safety Programs. National Collision Database (NCDB).

Transportation Safety Board (2013). Railway Investigation Report R13T0192.  

US-EU Bilateral ITS Technical Task Force. (2010). Driver Distraction: Definition and Research Needs – Report from the Expert Focus Group. US-EU Bilateral ITS Technical Task Force. Retrieved from:

US National Center for Statistics and Analysis. (2017, March). Distracted driving 2015. (Traffic Safety Facts Research Note. Report No. DOT HS 812 381). Washington, DC: National Highway Traffic Safety Administration.

Victor, T. W., Harbluk, J.L., & Engström, J.A. (2005).  Sensitivity of eye-movement measures to in-vehicle task difficulty. Transportation Research Part F: Psychology and Behaviour, 8, 167-190.

Annex A: Visual display distraction checklist

	Visual display guideline checklist The answer to each item should be "Yes" to limit distraction
1. Physical location	1.1 Is the visual display located so that it does not interfere with the driver's view of the road or any of the existing controls and displays?	Yes/No
	1.2 Is the display positioned in the forward view as close as possible to road centre, in line with the driver's forward view without obstruction?	Yes/No
2. Content of visual displays	Visual displays that are not to be used by the driver should be locked out so that the driver can't see their content while the vehicle is in motion. 2.1 If there is any video content and/or moving images (e.g., live or prerecorded video-based communications, entertainment, advertising, etc.), is it locked out while driving? Exceptions: content from backing cameras, blind spot cameras and navigation systems.	Yes/No
	2.2 If there are images that are displayed, are they relevant to driving (e.g., for navigation or to assist the driver in making a selection in the case of an infotainment system)?	Yes/No
	2.3 If there is text displayed, is it relevant to driving?	Yes/No
	2.4 If there is any automatically scrolling text, is it locked out while driving?	Yes/No
3. Visual interaction	The visual interface should be designed so that the driver can complete the task with brief, sequential glances to minimize impact on driving. 3.1 Can the driver complete a given task with a single glance or a series of individual glances each with a duration of 2 seconds or less?	Yes/No
	3.2 Can the task be completed with less than 12 seconds total glance time away from the forward view?	Yes/No
4. Task interaction	4.1 Can the driver keep at least one hand on the steering wheel during interactions with the system or display?	Yes/No
	4.2 If there is text that needs to be manually entered (e.g., for navigation destination entry, text-based messaging, other communication), is this function locked out while driving?	Yes/No
	4.3 Does the system provide feedback (i.e., confirmation of the driver input)?	Yes/No
	4.4 Can the task be easily interrupted and resumed?	Yes/No

Annex B: Definitions

Image: Any graphical or photographic image that isn’t a video and is associated with a non-driving-related task. Internationally standardized symbols and icons, as well as Trademark™ and Registered® symbols, are not considered graphical or photographic images.

Lock out: Disabling one or more functions or features of a device so the related task can’t be performed by the driver while driving.

Task: A sequence of inputs leading to a goal. Drivers will normally persist until they reach the goal (Burns, Harbluk, Angell & Foley, 2010). An example of a well-defined and understood task is a driver entering a street address in a navigation system to help them get to a destination.

Video content: Moving visual images presented electronically. Includes entertainment, advertising and other visual content not related to driving, obtained from pre-recorded images, live images, video games or broadcasts (such as by television or over the Internet), and/or closed-circuit television.

Annex C: Rationale and supporting evidence

This Annex provides further details on this report’s recommendations for the following (as outlined in Table 2):

• Physical location
• Content of visual displays
• Visual interaction
• Task interaction

This content is largely based on the VTTI document and NHTSA Guidelines, which you can consult for more information.

Physical location

Driver workspaces that are ergonomically designed put frequently accessed displays in a central place. This makes it easy for the driver to view the displays.

Visual displays should be located to minimize distractions due to poor visibility (blind spots, glare and mirror placement), controls, instrumentation, and seat design and location (APTA, 2009). The visual display's location shouldn't interfere with existing controls for displays that are required for the primary driving task from the driver's normal seating position (Stevens et al., 2002), or obstruct the driver's view outside the vehicle.

The mounting location of the visual display should be in a location that is easy to reach and see. However, no part of the physical device should obstruct a driver's view of the roadway, any vehicle controls, or displays required for driving (EU, 2008; JAMA, 2004; NHTSA, 2013), or be in the pathway of an airbag. In general, visual displays that present safety-critical information should be laterally positioned as close as practical to a driver's forward line of sight, so the angle of incidence is a maximum of 15 to 30 degrees (Green et al., 1995; NHTSA, 2013; Stevens et al., 2002; Ross et al., 1996). The monitor of the visual display should be located in a place where:

1. Its reflection on the windshield does not obstruct the visibility of the forward field of view (JAMA, 2004)
2. The incoming light does not disturb the driver's perception of the visual display
3. The visual display is not covered by functional parts of the vehicle (e.g., the gear lever; Ross et al., 1996)
4. The visual display does not vibrate or change position when driven (Ross et al., 1996)

NHTSA (2013) recommends that the visual display should be mounted where the downward viewing angle, measured at the geometric center of each active display area, is less than the 2D Maximum Downward Angle or the 3D Maximum Downward Angle. It recommends that visual displays with information relevant to driving and all visual displays requiring long sequences of interface be placed within approximately a 30° downward viewing angle of the driver's normal forward view (EU, 2008).

ISO 16121-3:2011 (2011) provides guidance for the location of various displays and their controls in bus cabs. Only controls for equipment that is not frequently operated may be displayed on the roof console over the driver's workplace. The monitor and controls should be out of the reach of the driver while seated.

See ISO 16121-2:2011 (2011) for visibility requirements pertaining to the driver's workstation in buses.

Content of visual displays

Visual displays and their associated functions that are not to be used by the driver during driving should be inoperative (locked out) or presented in a way the driver cannot see while the vehicle is in motion (Campbell et al., 2016; EU, 2008; JAMA, 2004; NHTSA, 2013).

Video content

The display of video content (and moving images), including live or replayed television broadcasts or video from any source should not be displayed while driving (e.g., JAMA, 2004). Video images from passenger monitoring cameras should not be displayed while driving. Allowable exceptions are displays of the area behind a vehicle while backing (rear view camera) and map displays in navigation systems (NHTSA, 2013). Content from blind spot cameras is also an exception.

Images

Graphical or photographic images that are not relevant for driving should not be displayed or viewed while driving. Exceptions include driving-related images, including maps, images displayed for aiding a driver to efficiently make a selection in the context of a non-driving-related task, and internationally standardized symbols and icons (NHTSA, 2013).

"Graphical or photographic image" means any non-video graphical or photographic image. Internationally standardized symbols and icons, as well as Trademark™ and Registered® symbols, are not considered graphical or photographic images (NHTSA, 2013).

Exceptions:

1. Displaying driving-related images including maps (assuming the presentation of this information conforms to all other recommendations of these Guidelines). However, we do not recommend the display of map informational detail not critical to navigation, such as photorealistic images, satellite images, or three-dimensional images.
2. Static graphical and photographic images displayed for the purpose of helping a driver to efficiently make a selection in the context of a non-driving-related task (e.g., music) is acceptable if the image automatically goes away from the display when the task is complete. If appropriate, these images may be presented along with short text descriptions that conform to these guidelines.
3. Internationally standardized symbols and icons, as well as Trademark™ and Registered® symbols, are not considered static graphical or photographic images.

Text to be read

Non-driving related text should not be displayed or read while driving. According to NHTSA, 2013, this includes but is not limited to:

• books
• periodical publications (newspapers, magazines, articles)
• web page content
• social media content
• text-based advertising and marketing
• text-based messages and correspondence

Driving-related text should be brief and easily understood. We provide visual interaction recommendations in the following section.

There are many design features that affect ease of comprehension for text displayed on visual displays. These include message complexity, use of colour in visual displays, character height, text legibility and glare. Relevant references are provided in the VTTI report and Campbell et al. (2016) for further information.

Automatically scrolling text

Automatically scrolling text (horizontally or vertically) that is moving at a pace not controlled by the driver should not be used on visual displays (NHTSA, 2013).

Visual interaction

The visual display should be designed so the driver can complete the task with brief, sequential glances to minimize impact on driving (Campbell et al., 2016).

When tasks are visually demanding, drivers reduce their attention to the forward view while paying attention to the in-vehicle task. In both simulator and on-road driving research, this time away (measured by percentage of glances exceeding 2 seconds) has been shown to increase with task difficulty (Victor, Harbluk, & Engström, 2005). Naturalistic driving research has shown that glances away from the road for longer than 2 seconds are associated with increased crash risk (Klauer et al., 2006; NHTSA, 2013).

The total time that a driver looks at the visual display (away from the road) to complete a task should not exceed 12 seconds. This is the cumulative sum of the individual glances, each not exceeding 2 seconds (NHTSA, 2013).

Task interaction

The driver must be able to safely control their vehicle. Operation of the visual display system should allow the driver to keep one hand on the steering wheel (EU, 2008; JAMA 2004; NHTSA, 2013).

Manual text entry should be prohibited while the vehicle is in motion. This includes text-based messaging, other communication or Internet browsing, as well as navigation system input while driving.

The system should provide timely feedback and confirmation of driver input so the driver does not feel compelled to check the visual display more than necessary. The driver should receive feedback or confirmation of their input within .25 seconds.

Feedback should be provided to the driver if the system's response speed exceeds 2 seconds, to make it clear that a change occurred (NHTSA, 2013).

Task interruption and task resumption

Drivers should be able to stop and resume the steps of a task during its completion in order to not feel rushed or compelled to continue the task.

The driver should be able to control the pace of the interaction with the system (Campbell et al., 2016; EU, 2008). The driver should be able to erase inputs without having to restart the entire task. The system should display previous input to remind the driver where to restart the task.