This is the sixth article in our series, Moving the Masses, about managing the flow of crowds of individuals, be they drivers or pedestrians, shoppers or commuters, birds or ants.
A major issue for road safety is collisions at intersections between vehicles and vulnerable road users such as cyclists, motorcyclists and pedestrians.
In such collisions, often the driver is momentarily unaware of either the vulnerable road user or of their planned path through the intersection. While many factors can cause this lack of “situation awareness”, the design of the intersection is critical. With numbers of vulnerable road users increasing, how intersections are designed requires urgent attention.
The status quo
If you look at the intersections in your local area, many appear to have been designed primarily with drivers and efficiency in mind. The designs show little consideration of the needs of vulnerable road users. Typically, we see high speed limits, no dedicated bicycle lanes through the intersection, no filtering lanes for motorcyclists, and short crossing times for pedestrians.
This can make it difficult for vulnerable road users to pass through safely. And critically, the lack of overt protection for these vulnerable users also reduces drivers’ expectation of encountering them. This can lead to something that we call a “looked-but-failed-to-see error”: drivers are not aware of vulnerable road users even though they may have looked at them (this phenomenon is explained here).
In response to these problems, we recently completed research using a series of on-road studies to understand:
how different road users interact at intersections
what they need to know to support safe interactions.
Our next step involved using a sociotechnical systems-based design process to create new intersection design concepts. A sociotechnical system is any system in which humans and technology interact for a purposeful reason. Our aim was to develop a series of new intersection designs that better support the “situation awareness requirements” of all users.
Understanding the diversity of users
The most important finding from our on-road studies was that different road users experience the same intersection situations differently. Critically, these differences can create conflicts.
For example, drivers tend to be concerned with what is ahead of them, and specifically the status of the traffic lights. In contrast, cyclists and motorcyclists are concerned with working out a safe path and then filtering safely through the traffic. Thus, drivers who are not expecting them are often not aware of them or of what they might do next.
A key implication of our findings was that intersections should be designed to cater for the diverse situation awareness needs of all road users. The environment should facilitate safe interactions by ensuring that all road users are aware of each other and understand each others’ likely behaviours.
Based on this, we set about designing a series of new intersections using a sociotechnical systems design approach. Among other things this approach aims to create systems that have adaptive capacity and can cope with a diverse set of end user needs.
To achieve this, it proposes several core values, including that:
- humans should be treated as assets rather than unpredictable and error-prone
- technology should be used as a tool to assist and not replace humans
- design should consider the specific needs and preferences of different users.
Designs for better intersections
We used these values as part of a participatory process to create three intersection design concepts. The design brief was to replace one of the intersections from the on-road studies (see below).Author provided