One hundred and thirty participants (70 males, 60 females), aged between 18 and 40, took part in this research to test the relative conspicuity of eight different test-garments. A simulated driving situation was produced where the participants were required to fixate on a central task (simulating driving) while searching coloured slide photographs to detect a road worker wearing a test-garment, located in one of eight different positions, against four rural and four city road scenes.
The overall results showed that the fluorescent orange garment had the shortest detection time, with fluorescent (lime) yellow being the second shortest. This difference was not statistically significant. Reflective stripes on the garments impaired rather than improved daytime conspicuity. Fluorescent green and the combination garment (fluorescent orange/yellow with reflective stripes) were clearly less visible than the fluorescent yellow and orange garments. The darkest and brightest garments (blue and white) were the least visible garments against most backgrounds.
Detection times were shorter when the colour of the garments were known to the observers, and for garments against rural backgrounds compared to the more complex city backgrounds. The longest detection times were for road workers positioned at the far left and right positions, and shortest for the position on the top of the slide stimuli. No differences were found between the detection times of colour vision impaired participants compared to participants with normal vision. Analysis of some participants' eye movement behaviour revealed that they used mainly peripheral vision to detect the road workers. It was recommended that the colour of the safety garments be standardised and that either fluorescent orange or yellow be chosen.