Therefore, you who cycle in the dark should learn what biomotion means

Scientific knowledge about how motorists perceive cyclists in the dark can be life-changing during the dark part of the year. To take a shortcut, it can be stated that reflexes that highlight the cyclist's movements in a clear way are most effective. Sweden by Bike had the privilege of asking some questions about reflexes to Paul Hemren, who is assistant professor of Information Technology at the Department of Information Technology at the University of Skövde.

You have researched how motorists perceive cyclists in the dark. How did you conduct the research?

The purpose of the project has been to develop reflex-based aids that improve motorists' ability to detect cyclists in the dark. A further aim of the project has been to make cyclists aware of their actual visibility and fellow road users' perception of their visibility. According to the Swedish Transport Administration (2014:030), cyclists' behavior and their interaction with other road users are important factors in increasing cyclists' safety. We investigated visibility by measuring how many cyclists, and at what distance, were detected by the car drivers in a driving simulator environment where the drivers drove a car along a video-recorded road loop through Skövde's urban environment. There were indeed different places and different circumstances within the Skövde urban environment.

What questions did you start from?

The project's concrete questions are:

  1. What differences in visibility to motorists exist between three different reflective patterns (legal, vest and biomotion) for cyclists at night and at different locations along a road?
  2. Do reflective patterns based on biomotion lead to motorists detecting cyclists at longer distances compared to legal gear and compared to cyclists wearing reflective vests?
  3. What impact do different locations have on cyclists' visibility? Is the reflective vest as effective when there are many other light sources in the environment compared to when there are no other competing light sources?

To get answers to these questions, cyclists were recorded wearing the three different reflective patterns and at twelve different locations along a road loop in central Skövde.

The results showed a clear visibility advantage for cyclists wearing a reflective pattern that highlighted the human movement pattern around the legs (knees and ankles) and on the bike helmet, what we call Biomotion.

Paul Hemeren, Bitr. professor of information technology at the University of Skövde.

What have you come up with? 

The results showed a clear visibility advantage for cyclists wearing a reflective pattern that highlighted the human movement pattern around the legs (knees and ankles) and on the bike helmet, what we call Biomotion. The difference was palpable. With the cover set Biomotion, it could be about twice the distance (60 meters) compared to the two other cover sets Laglig (32 meters) and West (33 meters).

The follow-up interviews also showed that visibility was best for Biomotion as the reflexes moved when the cyclist pedaled or moved their head and this movement pattern seemed to clearly improve the visibility of the cyclists according to the participants' responses. Leg and head movements can show what the cyclists will do in certain situations, such as whether to turn or cycle straight ahead. However, the difference in visibility between West and Legal was relatively small despite the fact that the Legal set did not use any reflective material at all. This result was somewhat surprising because reflective vests are usually used when cyclists and pedestrians want to be visible when it is dark outside. Our results replicate previous findings with similar questions (Wood et al., 2012). This previous research also showed superior visibility when the reflector placement emphasizes biomotion compared to vest-wearing cyclists and cyclists who did not wear any reflectors at all.

So it is biomotion that applies?

In terms of general advice from authorities and other actors that have to do with safe cycling, biomotion positioning of reflexes should become basic and common practice. Our investigation has independently replicated previous findings from other researchers. We have used a different method where we have emphasized the importance of visibility at different locations along a road loop in an urban environment. This somewhat more naturalistic setup further strengthens the credibility of our results and that it is very reasonable to claim that a reflex pattern that emphasizes the cyclist's biomotion pattern provides the best visibility.

Other tips and advice for cyclists in the autumn darkness?

A key lesson from this research is understanding how superior a reflex pattern that highlights biological movement is compared to the other clothing sets tested. Along with other similar results, it becomes important to develop an awareness of how much more visible a cyclist can become with the right reflex placement. This means not least that cyclists should develop a better perception of their own visibility in traffic with the help of the results of this survey. The traffic safety benefit here is about more detected cyclists and at longer distances, which gives motorists more time to act, which in turn leads to fewer accidents between cyclists and motorists.