Road Operators may need to be involved in the specification, design or purchase of a wide range of Intelligent Transport systems (ITS) products and services. How these ITS are designed will determine the efficiency, effectiveness and satisfaction with which they are used. To promote well-designed ITS, a wide range of standards, guidelines and other material is available which aims to capture good practice and advice. The range of information available includes:
A number of parties have a role to play in the development and use of standards and guidelines – and other information sources:
There are many general checklists and style guides concerning human interaction with technology. However, it is important to be aware of their limitations:
Standards and guidelines are likely to be relevant both in the procurement of ITS products and services and in operational activities involving ITS. Human factors standards and guidelines have a role in these activities. Road Operators may contribute to development of international standards, and/or to more local guidelines and Codes of Practice.
Road Operators have a duty of care to the users of their road networks. Tunnels are an example of road infrastructure that may be designed or managed by the Road Operator – and if human factors are not sufficiently addressed – they can raise significant ITS equipment and safety issues. In terms of ITS information provision, the Road Operator should ensure that everything provided is as clear and correct as possible – and that the ITS provided is safe, well maintained and fit for purpose so that it can be easily used. To help with these duties, one way is to use (and require sub-contractors to use) relevant standards and guidelines – including those related to human factors.
The Road Operator has responsibility for the work and conduct of their staff – including responsibility for any ITS which may be used as part of their jobs. The Road Operator may own or operate road vehicles as part of a fleet. Recovery and incident vehicles may have additional ITS equipment fitted for fleet management and communications. The standards and guidelines described here are relevant for these situations.
The Road Operator may also be responsible for the design and operation of traffic control centres – and for the staff who work there. Human factors issues are very relevant and important in this context – and a range of relevant standards and guidelines exist which, when properly applied, should assist the efficient running of the centres.
A standard is not the same as a law and, of itself, has no legal force. However, it can be quoted in a legal contract and form part of a legal document. It can also be adopted in whole, or in part, in regulations or other legal instruments. Standards may also be identified as representing “state of the art” in legal arguments and may be used as the basis for regulations or directives.
Standards (and guidelines and other information) may not be entirely neutral. They are developed by people and may be influenced (consciously or unconsciously) by bias or a particular point of view.
Some standards may contain commercial intellectual property (for example, concerning a specific interface) – so widespread adoption can be financially advantageous to specific organisations.
The world of standardisation can seem obscure and opaque to those unfamiliar with it – transport professionals may be unaware of the development of relevant standards impacting on their operations. Investment in awareness of standards and standards development has a cost.
The requirement to adopt a particular standard (or other guideline document) may require new ways of working and challenge existing organisational boundaries.
For further information see ITS Standards and Legal and Regulatory Issues
Access to standards and the cost of standards may be a particular issue. Standards are available in a range of common languages – but not all languages are covered.
The process of standardisation can be long and costly, involving international meetings and this may be a barrier to participation for some countries and organisations. As a result, the standard may be designed for use in a context of operation that is not entirely relevant to a developing economy.
With the growth in deployment of ITS and the information and communication options available to drivers, the modern car has been described as ‘a SmartPhone on wheels’. Information may be presented both in-vehicle and externally and needs to be relevant, timely, consistent and useful. The challenge for designers – supported by standards and guidelines – is to provide the information and services demanded by drivers that are usable without causing unsafe distraction and overload. In-vehicle human factors have a number of important consequences for Road Network Operations, in particular:
As well as information and entertainment, in-vehicle sensor, communications and processing technology can assist drivers by providing advice and warnings concerning the vehicle’s immediate environment. These warnings have to be perceived, understood as relevant, and acted upon appropriately if they are to be effective. Guidelines in this area are now emerging.
Driver error is consistently identified as a contributory factor in over 90% of vehicle crashes. Better design of the driver interface has the potential to keep the driver “in-the-loop” whilst increasing safety. Additionally, many vehicles now include ITS that provide automation of specific elements of the driving task. Systems can even be designed to intervene in vehicle control to avoid or mitigate an impending collision. Nevertheless, usability issues around how the vehicle ‘feels’ and responds, and how control is partitioned between the vehicle and the driver, are crucial to achieving driver trust, acceptance and adoption. The RESPONSE Code of Practice provides at least some guidelines in this emerging area and further research is underway.
It is good practice for new ITS vehicle applications or in-vehicle information and communication products to be simulated and trialled with users to understand better the interaction between them and any consequences
There are many international regulations on vehicle design and many standards and guidelines relating to information and communication systems (ICT) and warning and assistance systems.
A considerable volume of international regulation exists in relation to design requirements for motor vehicles that aim to ensure that technology within vehicles can be used safely. The United Nations Economic Commission for Europe’s (UNECE) Transport Division provides secretariat services to the World Forum for Harmonization of Vehicle Regulations (WP.29). The World Forum provides the regulatory framework for technological innovations in vehicles to make them safer and to improve their environmental performance. There is also a range of international law that affects drivers’ interaction with their vehicles and ITS. In Europe these take the form of Directives from the European Commission. In the US, there are both national and state laws on ITS human factors issues such as hand-held phone use and texting while driving.
Although not legally binding, international standards provide process, design and performance advice. The following are the main international working groups in areas relevant to vehicle design and usability:
Much of the knowledge from these standards has been incorporated in design guidelines and codes of practice. (See ITS Standards)
The European Commission (EC) has supported the development of a document called the ‘European Statement of Principles on HMI’ (referred to as ESoP) which provides high-level HMI design advice (EC 2008). As an EC Recommendation it has the status of a recommended practice or Code of Practice for use in Europe. It also contains 16 Recommendations for Safe Use (RSU), which build on Health and Safety legislation by emphasising the responsibility of organisations that employ drivers to attend to HMI aspects of their workplace. Adherence to the RSU is likely to promote greater acceptance of technology by drivers.
The design guidelines of the ESoP comprise 34 principles to ensure safe operation whilst driving. These are grouped into the following areas: Overall Design Principles, Installation Principles, Information Principles, Interactions with Controls and Displays Principles, System Behaviour Principles and Information about the System Principles.
The US motor vehicle manufacturers have developed ‘Alliance Guidelines’ that cover similar, high-level, design principles as the ESoP. The Guidelines (Auto Alliance 2006) consist of 24 principles organised into five groups: Installation Principles, Information Presentation Principles, Principles on Interactions with Displays/Controls, System Behaviour Principles, and Principles on Information about the System.
The USA’s National Highway Transportation Safety Administration (NHTSA) has worked with automobile manufacturers and the mobile phone industry to develop a set of guidelines for visual-manual interfaces for in-vehicle technologies. These are based on the ESoP/Alliance guidelines and introduce some specific assessment procedures (NHTSA 2013). The NHTSA also plan to publish guidelines for portable devices and guidelines for voice interfaces.
The Japanese Auto Manufacturers Association’s (JAMA) Guidelines consist of four basic principles and 25 specific requirements that apply to the driver interface of each device to ensure safe operation whilst driving. Specific requirements are grouped into the following areas: Installation of Display Systems, Functions of Display Systems, Display System Operation While Vehicle in Motion, and Presentation of Information to Users. Additionally, there are three annexes: Display Monitor Location, Content and Display of Visual Information While Vehicle in Motion, and Operation of Display Monitors While Vehicle in Motion.
Guidelines on establishing requirements for high-priority warning signals have been under development for more than five years by the UNECE/WP29/ITS Informal Group (Warning Guidelines 2011). There has also been work in standardisation groups to identify how to prioritise warnings when multiple messages need to be presented – and one ‘Technical specification’ (TS) has been produced:
In addition, two Technical Reports are relevant that contain a mixture of general guidance information (where supported by technical consensus) and discussion of areas for further research:
To help promote driver acceptance of Advanced Driver Assistance Systems (ADAS), a key issue is ensuring controllability. This has been addressed through guidelines. Controllability is determined by:
Drivers will expect controllability to exist in all their interactions with assistance systems:
The European project RESPONSE, has developed a Code of Practice for defining, designing and validating ADAS. The Code (outlined in the figure below) describes current procedures used by the vehicle industry to develop safe ADAS with particular emphasis on the human factors requirements for ‘controllability’.
Overview of the RESPONSE code of practice for design of in-vehicle information and assistance systems
Another European project, ADVISORS has tried to integrate the RESPONSE Code within a wider framework of user-centred design taking account of the usability of information, warning and assistance systems. The Intelligent Transport Systems (IHRA-ITS) Working Group of the International Harmonized Research Activities – is developing a set of high-level principles for the design of driver assistance systems (IHRA-ITS 2012).
Human factors standards affect the design of ITS road infrastructure. Signage potentially has a significant impact, particularly on drivers, and there is a broad range of new and developing signage systems involving ITS. The most widely deployed signs, called Dynamic Message Signs (DMS), also known as Variable Message Signs (VMS) and Changeable Message Signs, (CMS) have developed in terms of technology. Experience of their use has been distilled into guidelines on their design and operation.
Two other areas where Road Operators may be involved in close consideration of human factors are the design of tunnels and control rooms. Both pose important safety and human factors issues for which human factors guidelines have been developed.
ITS is capable of presenting new and existing traffic information to road transport users in radically different ways from that of conventional traffic signs. Variable message signs can be implemented through a range of technologies. They can include text, pictograms and moving images with various colours. Other changeable signs, including those that display actual vehicle speed (and sometimes vehicle identification information), can be part of an ITS designed to influence driver behaviour with dynamic and targeted information. (See Use of VMS)
There is a broad range of new and developing signage systems involving ITS. For many of these, experience has yet to be developed into specific guidelines whereas relatively good information is available on Variable Message Signs (VMS).
Just as with conventional static signs, to be effective, VMS have to be noticed, understood and followed. These are human factor considerations primarily for drivers for which various guidelines exist on their design.
Conspicuity describes a sign’s prominence from a driver’s perspective. This depends on its optical properties such as luminance (amount of light entering the eye from the sign) and contrast ratio, as well as factors such as size and contrast with surroundings. The general advice is for high luminance and high contrast signs.
Legibility describes the extent to which sufficient detail is visible at a given distance. This also depends on whether it is necessary to read a shape or individual letters. Legibility is enhanced through large letters but there is a trade-off against message length and any sign size. The resolution also depends on the underlying technology (such as the size of the smallest individually controllable image element).
The limited time that drivers have to read a sign restricts their perception of the length and complexity of the message. Some “rules of thumb” exist concerning how many words can be read during different glance times. Well-designed pictograms can quickly communicate concepts and are not language-specific, for which some advice about their design and use is available.
Message comprehension is basically a human task of pattern recognition, and in assessing whether a VMS will be comprehensible it is important to understand:
Relevant to the context of use, visual clutter in the driving environment has been extensively researched and shows that distractions in the visual scene reduce drivers’ performance when responding to signs. For example, advertisements, and particularly ones with dynamic images, can decrease the effectiveness of other signage.
Advice is available on a range of VMS design issues including message length, message formatting, mixing text and pictograms and using dual-language text. There is some evidence that blank VMS confuse drivers which suggests that it is probably best to always carry some message on a VMS, such as a road safety warning or – when available – current point-to-point journey times.
Advice also exists on how to measure comprehension and how to assess whether correct actions – that are timely, credible and appropriate – are taken.
Tunnels are an important feature of the road infrastructure and one where safety in their use is a crucial issue – because accidents in tunnels, and particularly fires, can have dramatic consequences. Two thirds of crashes happen at the portal areas but accidents inside the tunnel tend to be more serious. The key human factors issues seem to be related to lighting, lack of variation, and lack of landmarks to give any speed or distance references.
In long tunnels driver monotony and reduced concentration can be addressed through the design of lighting – for example by creating the impression of driving through several shorter tunnels by making transition zones using different lighting effects. Monotony can also be reduced by designing-in gentle curves and short straights (without breaching guidelines for safe viewing distance) (See Mont Blanc Tunnel Management System).
Intelligent monitoring and control systems are frequently used for air quality temperature, water seepage, fire, radio connections, lightning systems, traffic lights, emergency equipment and many other critical functions – so that if faults or incidents occur, the tunnel can be automatically closed to traffic.
In the European Union a Directive describes minimum safety standards. Much of it relates to organisational and operational schemes for testing, inspecting, training and equipping the emergency services – rather than human factors design issues. A PIARC report is available that reviews user behaviour in road tunnels in both normal and critical situations and provides additional recommendations for tunnel design and operation based on human factors considerations. It also covers what can be expected in the future from ITS regarding improvement of safety in tunnels. In summary, the recommendations are to take greater account of human factors in road tunnel design, particularly concerning:
Traffic control centres are an integral part of ITS – and the application of human factors considerations can play a pivotal role in increasing efficiency, productiveness, operator well-being and safety. It can also help to reduce the potential for, and consequences of, human error. Human factors issues in control centres include physical aspects (from the design of individual controls at operating stations to the building’s design and location) and procedural aspects (such as staffing and shift scheduling). (See Traffic Control Centres)
In terms of the physical ergonomics, a suite of international standards (under the umbrella of BS EN ISO 11064) is available that deal specifically with the ergonomic design of control centres. There is also an extensive suite of standards (under the umbrella of BS EN ISO 9241) that deals more generally with the ergonomic requirements for office work with visual display terminals (VDTs) and the ergonomics of human-system interaction.
Many control centres will need to operate around the clock and so may use a shift work policy. This can have negative effects on personnel if not implemented correctly. Employers must consider the workload, the work activity, shift timing and duration, direction of rotation and the number/length of breaks during and between shifts. The UK Health and Safety Executive has produced a book that provides practical advice on implementing and managing shift work.
ISO 11064:
Vulnerable road users (VRU) are those users who are at great risk because of insufficient physical protection or because of relative high speed difference with potential conflicting modes (Vulnerable road users diagnose of design and operational safety problems and potential countermeasures, PIARC, 2016).
Through this definition a specific attention is given to four main categories of road users, i.e:
Although there are few standards and guidelines concerning human factors of ITS for these groups of people, vulnerable road users are likely to benefit from a range of safety-enhancing ITS and supporting standards and guidelines on their design and implementation. (See Road Safety)
Accessibility or "ability to access" often focuses on people with disabilities or special needs and their of access, enabling the use of assistive technology.
This technology can include ITS to improve the capabilities of individuals with disabilities in the road context. Few standards or guidelines exist but ITS which is implemented via web applications can take advantage of published guidelines for accessibility. The Web Accessibility Initiative (WAI) has developed the Web Content Accessibility Guidelines (WCAG) which explains how to make Web content accessible to everyone, including people with disabilities.
Accessibility legislation in some countries has prompted the development of guidelines for disabled persons to access public transport (such as those published by the National Disability Authority in Ireland in 2005). This includes human factors issues.
Special provision for disabled drivers might include ITS. Guidelines exist for vehicle adaptation, but not specifically for ITS.
With an increasing number of older drivers, automotive technology that helps keep older drivers safe is expected to grow in importance. Technology including ITS may help to prolong safe mobility particularly in suburban and rural areas, where public transportation options are limited. Many ITS devices may be developed to assist older drivers with aspects of their driving task. “Design for all” is an important concept as designs benefitting the least fit, older person, are likely to help drivers of all ages and skill levels. The Massachusetts Institute of Technology’s (MIT) Age-Lab, is for example, doing work in this area. Older road users include pedestrians and cyclists. Specific designs for older road users are being developed – although standards and guidelines on HMI are yet to emerge.
A range of technology is emerging based on ITS and cooperative systems that can potentially alert a driver to the presence of a cyclist or pedestrian (for example, in their blind spot). General ITS and human factors guidelines will apply to these situations although little specific guidance is currently available.
As with other vulnerable road users, riders of powered two wheelers (PTW) are likely to benefit from a range of safety-enhancing ITS for drivers and supporting standards and guidelines for their design and implementation.
ITS for PTW and other light vehicles is largely in the research and development phase and many ITS applications could be used to improve rider safety including Adaptive Cruise Control, Incident Warning, Blind Spot Monitoring, Forward Collision Warning, Obstacle Warning, Automatic eCall.