The users of the road system are diverse and complex—including drivers and passengers, road workers, pedestrians, cyclists, people using emerging micromobility options such as electric scooters, and, in some contexts, horse riders—each with their own needs and vulnerabilities3 that need to be taken into consideration. Competition exists between modes and users; the interfaces and interdependencies within the system—involving the physical space, vehicles and road users—often lie at the heart of any safety issue. The whole system therefore needs to be designed and operated using a human-centric perspective to achieve the required outcomes—with the evidenced-based Safe System approach guiding the process.
Behavioural science seeks to identify the factors that influence people’s thinking, emotional reaction and ultimately their physical response in any given situation or environment. Fundamentally, it seeks to understand why people do what they do and to predict responses in each context. Without this intelligence, any attempt to change human behaviours and interactions—and create a safe system—will likely fail. Developing safe transport systems therefore relies on understanding how to incorporate a proper consideration of the human factors involved.
Behavioural science will enable/assist system designers to:
- recognise that people are fallible. This means accepting that human error can, does and will occur
- understand why people do certain things – recognise the mix of societal norms and learned behaviours and how to encourage (nudge) shifts
- understand the root causes that led to the human error
- understand how and why people respond to/modify their behaviour in response to mitigations – particularly when these may not align with what designers assumed people would do
- identify and understand the parts of the system that failed
- go back to the beginning of the development of any solution, then identify and examine all the factors that influenced the outcome.
When transport system safety specialists can adequately respond to all these considerations, they are then equipped with better evidence and understanding, enabling the delivery of effective, intelligence-led solutions. These solutions result in safer outcomes as a result of an enhanced multi-dimensional approach to understanding and improving human interactions within road systems.
Getting to the Root Cause
When presented with an issue, it is important to look beyond the surface and get to the root cause—why did this happen and what factors led to it—before starting to think about a solution. Otherwise, there is a risk of solving the wrong issue, and the problem ultimately persists. Road transport safety professionals carry out incident/crash investigations to gain a full understanding of what caused each one, and then design and target mitigations. Then they need to communicate effectively, explaining why the mitigation is necessary and how it makes a difference in order to influence behaviour and responses, and to achieve the intended outcomes.
Intelligent transport systems that are well-designed from a human-centric perspective:
- are intuitive – combining and using features such as road markings, signing, fencing, etc. that take account of how users see and understand the system/network that they are using
- present the right information, in the right place and at the right time
- combine “push and pull” (instruction and encouragement)
- provide the right mix of education, enforcement, encouragement and engineering to achieve the required result
Once a road-transport system has been implemented, system designers then need to monitor how it used and, where necessary, take action to modify the system to accommodate actual behaviours and revised predictions—based on the available evidence—and, where practicable, devise education campaigns that encourage compliant behaviours. Intelligent monitoring of the effectiveness of mitigations and the responses to them from a behavioural point of view is crucial, as is the willingness to learn and change mitigations and solutions as more responses and evidence is gathered/assimilated.
WSP Examples Illustrating the Integration of Human Factors
Human Factors Research, Road Tunnels, 2020—North and Mid Wales Trunk Road Agent
This research provided a detailed understanding of how road users would react in a tunnel emergency that required evacuation. The research explored whether road users in a panicked state would be able to use the existing evacuation equipment to aid their escape, and identified potential issues that require mitigation. It also provided insight into the many factors, both physical and psychological, that influence behaviours. The research concluded the biggest area of improvement required is education. The road users need to understand what to do in the event of an incident in the tunnels in order to prevent human error and promote safe evacuation. It is also important as part of the education to advise road users on how to reduce the risk of incidents in the first place, such as vehicle maintenance to prevent breakdowns/engine fires.
A2M2 Connected Vehicles Trial, 2018 - 2020—Highways England
This project provided insight on how new systems influence driver behaviour in congestion, junction management (traffic lights) and roadworks. The work involved conducting interviews in order to obtain user feedback. Connected vehicles were trialled where participants experienced messages on roadworks, road signs, speed limits, traffic light changes and lane changes. The project also qualitatively analysed the data by examining the interviews with participants and presenting these results in a report. The A2M2 project won ITS project of the year at the ITS (UK) President’s dinner.
Ipswich Connected Vehicle Pilot as part of the Connected and Automated Vehicle Initiative, 2020–Queensland Department of Transport and Main Roads (TMR), Australia
The largest component of TMR’s Connected and Automated Vehicle Initiative (CAVI) is the Cooperative Intelligent Transport Systems (C-ITS) Pilot. The pilot takes place on public roads in and around the City of Ipswich. This project provides insight on how new systems, utilising Cooperative Intelligent Transport Systems (C-ITS) can influence driver behaviour.
Testing will assess the value proposition of C-ITS safety use cases, including vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) applications. There will be around 500 public and fleet vehicles retro-fitted with C-ITS technologies, and roadside C-ITS devices installed on arterial roads and motorways. These devices allow vehicles and infrastructure to talk to each other to share real-time information about the road and to generate safety-related warning messages for drivers.
The use cases being trialled include in-vehicle speed warning, emergency brake warning, turning warning for bicycle riders and pedestrians, roadworks warning, back-of-queue-warning, and red-light-violator warning, among other hazard warnings in the road environment. Quantitative data analysis will be employed for safety evaluation: analysing driver behavioural response to C-ITS alerts to infer crash reduction potential. The project will also employ surveys to assess user perceptions.
Bruce Highway Interchange Virtual Reality Usability Testing, 2019, Queensland, Australia
WSP led the behavioural evaluation and design of usability testing for the new Bruce Highway Interchange. This is a complex intersection design that has multiple decision points in quick succession, visibility issues and significant safety consequences if a driver makes a wrong decision. We combined virtual reality technology, behavioural science techniques and digital engineering data to simulate driver experience, understand why driver behaviours occurred and provide practical adjustments to the design—allowing the project team to save costs and improve safety outcomes for public road users.
The ever-growing human factors interdisciplinary specialism contributes to the development of effective intelligent transport systems by keeping people at the centre of the design, build and use of these systems—and thereby fostering safe and efficient interactions on roads. There is a need for the transport sector to go beyond the standards and models in place, to test and design for human behaviours and help standards evolve. Continually gaining insight from human factors studies and channelling that intelligence into projects will strengthen road-safety efforts seeking to make Vision Zero a reality in communities around the world.
1 This assessment framework is explored in article No. 2 of the ITS-Vision Zero series
2 System designers – according to the Vision Zero approach - include policymakers, politicians/government officials, infrastructure owners and operators, planners, engineers and road designers, vehicle manufacturers, trauma and hospital care providers, plus any other provider and enforcer of the road transport system. Each contributes important knowledge and expertise to help make and keep roads safe.
3 While “vulnerabilities” exist in relation to all road users, Vision Zero characterizes “vulnerable” users as those most at risk in traffic, as they do not have an outside shield to protect them from the force of impact in a crash. See Vision Zero: Setting a Higher Standard for Road Safety, WSP, p. 9