The way urban planners currently assess the safety of a road involves counting the number of accidents on that particular road. Essentially, this means that there’s a “literal human cost” to measuring how safe a street is, says Megan Ryerson, a transportation engineer and urban planner at the University of Pennsylvania who has recently come up with a new metric for measuring the concept of road safety.
Ryerson’s new technique is based on biometric data that can recognize dangerous or challenging parts of urban infrastructure before a crash ever occurs, thus prompting city officials to implement safety measures preventively.
As part of her project, a group of cyclists biked around Philadelphia wearing eye-tracking glasses and a gyroscope that collected data on when and where they moved their eyes, as well as at what points in their journey they turned their heads around.
By tracking these movements, the team behind the research was able to assess the stress levels and cognitive workload the cyclists felt while riding through different types of road infrastructure, like traveling in a protected bike lane for one stretch, and then in a “mixing zone” — without any separation between bikes and cars — the next.
As reported by Fast Company, the researchers tracked four workload indicators for the study: gaze velocity (the rate of eye movement per second) and position; vertical and lateral angles; and vertical and lateral gyroscope angles, which correlate with things like bikers turning their head to check over their shoulder.
“When cognitive workload is very high, the chance that you make an error is much, much larger than when your cognitive workload is low,” says Ryerson. In case a road design incites a higher cognitive workload and then something unexpected happens, it becomes more difficult for the rider to process that new information and react in time.
While the fact that cyclists experienced higher stress levels and cognitive workload in less protected areas wasn’t shocking, there was one surprising finding: No matter their experience level, every cyclist had their highest stress moments in the same spots.
“Even if I, for example, am a ‘nervous, look-everywhere cyclist,’ and you are a ‘confident, looking-straight-ahead cyclist,’ we both had our highest stress moments in exactly the same spaces,” Ryerson says. “That finding alone says it’s the infrastructure that is eliciting these responses.”
Ryerson now hopes that her research will help change the definition of road safety away from crashes and deaths to being about stress, workload, and how people feel as they travel around a city.
Study source: Accident Analysis & Prevention — Evaluating cyclist biometrics to develop urban transportation safety metrics