Can roads truly be made safer? Yes, they can, and this handbook shows road designers and traffic engineers how, through a better understanding of road users – the “human factor”.

Over a million people are killed every year on the world’s roads. Road user error is often concluded to be one of the main factors contributing to road crashes, and many in the road safety world believe that road user error is inevitable. But it need not be inevitable in a transport system that is designed around the needs and capabilities of its users. This is where road designers and traffic engineers have a vital role to play. Over many years, they have developed their skills to optimise traffic movement and maximise safety. But they don’t always get it right. One likely reason is that they may lack a basic understanding of the abilities, limitations and needs of the very people they are designing for – road users.

The scientific discipline of “Human Factors” exists to support road designers and traffic engineers, so that they can put road users at the centre of their design thinking. It provides them with data, principles and knowledge that can be applied to designs to optimise human performance, minimise error and make the road transport system safer and more user-friendly. Human factors is not just of interest to professionals involved in behavioural programmes for road safety, it is also vital for the development of the professional skills that road designers and traffic engineers need, to do their job effectively.

This handbook – the first of its kind – seeks to show how an understanding of human factors can be applied in practical ways to the day-to-day tasks of designing and managing the road system to make it a safer and more user-friendly place to travel. The handbook is structured in a way that takes the reader through the fundamentals of road safety and human-centred design and then looks at road user capabilities, limitations and design needs before the majority of the chapters look at the practical application of this knowledge to the various aspects of road design and traffic management that professionals are involved in.

This handbook is also designed as a textbook, putting the human factor at the heart of basic education and training in road and traffic design for undergraduate and postgraduate students.

Here is the how and why of human factors for road designers and traffic engineers in one convenient volume based on the authors’ extensive knowledge, experience and expertise. Packed with case studies, human factors checklist questions, photos, do’s and don’ts, examples and practical exercises, it is a must-have for students and professionals alike.

Michael A. Regan, PhD, is an Emeritus Professor of Human Factors with the University of New South Wales Sydney (UNSW Sydney) Research Centre for Integrated Transport Innovation (rCITI) in Sydney, Australia. Prior to that he was Professor of Human Factors with rCITI, and before that Chief Scientist - Human Factors with the Australian Road Research Board (ARRB). Mike, as he is best known, has Bachelor of Science (Hons) and PhD degrees in psychology and human factors from the Australian National University and more than 25 years’ experience in transportation human factors and road safety research, teaching, policy development and consulting - in Australia, Europe and the USA. His specialist research interests include driver distraction and inattention, driver interaction with assisted and automated vehicles and human factors in road design and traffic engineering. Mike has authored, co-authored and co-edited more than 200 peer-reviewed publications, including four published books. He is a Fellow of the Australasian College of Road Safety and was the 25th President of the Human Factors and Ergonomics Society of Australia.

Rob (Robert) Morgan, BEng, MEngSc, is a traffic engineer and road safety engineer, based in Melbourne, Australia. He has over 50 years’ experience in these professional areas, and in transport planning. Rob has been the principal author of several national guidelines in road safety engineering and crash investigation. Since 1984, Rob has been an active member of the national committee responsible for Australia’s Manual of Uniform Traffic Control Devices (MUTCD), including being the original principal designer of Australia’s standard parking control signs, which are noted for their high levels of readability and comprehension. Early in his career Rob worked in the UK, followed by a decade in local government. Since 1993 he has been a consultant, including work in New Zealand and Canada. He has had extensive experience across Australia, leading frequent training workshops on road safety engineering topics. Rob is also a member of the UK Royal Photographic Society.

John L. Campbell, PhD, is a Principal Scientist with Exponent, in the US, with over 35 years of experience examining issues related to human factors, driver behaviour, roadway safety, and the contributing factors to roadway crashes. He is trained as a psychologist, with a PhD in Cognitive Psychology from the Claremont Graduate School and a Master’s Degree in Human Factors. He has developed design guidelines and other tools to support roadway design, crash diagnostics, and countermeasure selection. He has provided training to US State Departments of Transportation on human factors aspects of roadway design and operations. He also served as the chair of the Transportation Research Board’s (TRB's) Standing Committee on Human Factors of Infrastructure Design and Operations from 2016 to 2023. John led the development of the 3rd Edition of the Human Factors Guidelines for Road Systems - NCHRP Report 1148 and was a contributor to the 8th Edition of the “Green Book” (US Policy on Geometric Design of Highways and Streets) and the 2nd Edition of the Highway Safety Manual.