Bicycle Network: Behaviour

Fluoro no dark star

25 October 2010. Fluorescent vests give bike riders a false sense of visibility at night, and were not a significant improvement on black clothing, according to a recent Australian study.

Riders seem generally to have a poor understanding of what makes them visible.

Reflective vests, rated highly by many riders, were better than fluorescent but nowhere near as effective as reflective strips worn on the ankles and knees—which riders thought poorly of.

The study was conducted on a closed road circuit at night where driver participants of various ages were were in a specially equipped vehicle and bike rider participants wore various combinations of clothing.

The researchers were from the School of Optometry, Queensland Institute of Technology; Department of Psychology, Clemson University, South Carolina; and The Centre for Accident Research and Road Safety, Queensland.

The researchers said fluorescent materials had little visibility benefit at night, as they are activated only by UV radiation, which is lacking in headlights and streetlights.

"Cyclists appear to assume incorrectly that the visibility advantage of fluorescent materials is equivalent irrespective of lighting. Thus, cyclists who habitually wear fluorescent ­ as opposed to reflective ­ materials may considerably overestimate their visibility at night," they said.

"This may result in cyclists unintentionally placing themselves at elevated risk."

The study found that adding reflective ankle and knee markings provided a powerful enhancement of the cyclist¹s conspicuity.

That the cyclist only wore the reflectors on the ankles and knees and yet was still easily recognised suggested for the successful recognition of cyclists, marking just the ankles and knees may be sufficient.

The relatively low conspicuity levels of the cyclists when wearing the reflective vest alone is likely to be attributable to the lack of perceptible torso motion signifying the presence of a cyclist.

(The reflective strips used were 50mm- wide silver retro-reflective strips (3M Scotchlite 8910 silver fabric) positioned on the cyclist¹s ankles and
knees.)