Human-centred design the driving force behind road safety

Wednesday, 18 August, 2021

Road signs should direct drivers where to go, where to stop and where to turn. However, when driving, it is possible to miss certain signs completely, or get distracted when changing the radio station or turning down the air conditioning. Emeritus Professor Michael Regan, from the UNSW School of Civil and Environmental Engineering, is a psychologist specialising in transportation human factors. Professor Regan notes that traffic control devices, including destination signs, warning signs and traffic lights, need to be designed from a human-centred perspective to be effective. The road and transport environment is designed to help drivers get from point A to point B. However, Professor Regan notes that there is a fine line between what should be capturing the driver’s attention to help along the journey, and what is a risk of being a distraction.

“For example, things such as advertising billboards along highways draw the driver’s attention to whatever is being promoted in the ad. But at the same time, they are a source of distraction and may instead draw the driver’s attention away from things that are critical for safe driving — such as being focused on the road ahead. There are many factors that come into play when designing a transport environment that is safe for all users — but it needs to be designed from a human-centred perspective because, ultimately, we’ll be the ones using it,” Professor Regan said.

New safety star rating needed

The Australian New Car Assessment Program (ANCAP) gives star ratings for a vehicle’s ability to protect its occupants in the event of a crash. A higher rating is awarded for vehicles with active safety systems, such as autonomous emergency braking, which help the driver prevent or minimise the effects of a crash with pedestrians, cyclists, or vehicles. Professor Regan believes a similar system needs to be developed to rate how safe the design of roads are from a human-centred perspective, noting that some drivers may choose to drive on certain roads that are rated safer than others because they know they will contain signs and signals that are conspicuous, legible and comprehensible, meaning drivers are less likely to become confused and distracted.

“It’s very clear that people value safety when it comes to purchasing a new car, but safety shouldn’t stop there, it should include our road system too. These are just a small few of the many human-centred issues that would need to be considered in rating our roads,” Professor Regan said.

Signs of a good sign

For any traffic control device to be effective, it should be conspicuous and legible, with comprehensible messaging. Professor Regan’s work in the UNSW Research Centre for Integrated Transport Innovation (rCITI) has found that when a traffic light or sign lacks one or more of these characteristics, it can become a distraction. Professor Regan noted that some traffic lights or signs aren’t obvious to drivers because they’re hidden behind a tree or blocked by something. This can encourage drivers to adopt compensatory visual scanning strategies to try to see them, which takes their eyes off the road for longer than is necessary. To capture the attention of drivers, signs must not have anything obstructing the messaging, so that they are visible to drivers. The messaging must also be clear.

“For example, people generally understand what the different colours on traffic lights mean or that a stop sign, including its shape, indicates the driver needs to come to a complete stop. A sign can be confusing when the messaging is unclear or when you’re introducing a new symbol that many drivers aren’t familiar with. This takes away from the original purpose of the sign and becomes more of a distraction as drivers try to understand what the sign is telling them to do,” Professor Regan said.

Professor Regan also believes that signs need to be credible and widely accepted by road users, otherwise they will be ignored. “Let’s say you’re driving along the highway on a Sunday, and you pass through a work zone that would normally be operative on a weekday. And the speed limit as you drive through the work zone is 40 kilometres per hour, but the highway normally has a speed limit of 110 kilometres per hour. You look around but there is no roadwork activity or workers around. While it’s technically illegal, people are less likely to obey the 40 kilometres per hour sign because it’s not credible in this context,” Professor Regan said.

Distraction by design

The cockpit design of cars has changed over the years, to incorporate more interactive features such as touch screen displays and Apple CarPlay. While these are meant to enhance the driving experience, they can often be a distraction for the driver, with research revealing that approximately 70% of distractions are within the vehicle. Actions such as selecting radio stations with touchscreen displays, entering destinations into navigation systems or even reaching for something in the glove box while the vehicle is in motion, are all distractions that pose a huge risk to the driver.

“If you take your eyes off the road for two seconds, it’s been shown that you double your risk of a collision. Any longer than two seconds, and the risk of a crash increases exponentially. As vehicle cockpits inherit more functionality and become more interactive, we need to ensure the driver’s safety is not compromised,” Professor Regan said.

It’s not you, it’s me

In a perfect world, all road and transport environments will be designed from a human-centred perspective, to minimise human error and optimise safety. However, humans are still prone to conditions that may degrade driving performance and safety. Road users who are cognitively distracted — for example, when talking on their mobile phone about something complex or emotional — may see a traffic light change colour but not respond to it. This is known as intentional blindness, which Professor Regan describes as the look-but-fail-to-see phenomenon, and is an issue for drivers and pedestrians.

“Drivers and other road users will continue to be prone to distraction, fatigue and other human conditions. However, there is much that can be done, through good human-centred design, to enhance their safety and prevent crashes,” Professor Regan said.

Image credit: ©stock.adobe.com/au/Shuang Li

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