SUMMARY – colour has been exploited for conspicuity for thousands of years… the first bike safety campaign was ‘Ride Bright’ in London in the mid-70s… conspicuity clothing must generate a contrast to be effective… hi-vis is only effective when it is a DIFFERENT colour or shade to the riding environment… counter-intuitively, dark colours show up against light backgrounds… for an effective colour contrast use the colour wheel… if using hi-vis choose a colour appropriate to the riding environment… pink is a good all-round choice for daytime use… but there is unlikely to be a one-size-fits-all solution… don’t expect to be seen even when using hi-vis clothing…

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Why do motorcyclists use hi-vis clothing? In fact, why does anyone wear hi-vis? The answer is pretty obvious – to stand out by ‘being conspicuous’. As previously stated, the idea of using clothing and lights to help riders stand out was first promoted as a motorcyclist safety aid in the mid-1970s in a campaign in London called ‘Ride Bright’. And it’s been heavily exploited by manufacturers keen to sell their clothing products – check out the “be safe, be seen” strapline on the advert.

A bit of history. The idea of standing out in a crowd, of being ‘conspicuous’, isn’t new and almost certainly a lot older than most of us realise. Colour has been used for this purpose for thousands of years and perhaps not surprisingly, the Romans exploited colour very effectively. In battle, the officers almost certainly wore helmets with brightly-coloured crests. They were usually red, but other colours such as yellow and purple were used.

At this point, it’s worth asking a simple question; “what do we want to achieve when we say we want to be conspicuous?”

In the case of the Roman army, it was to help soldiers locate their officers – and thus their units – in the melee of battle. The coloured crests were conspicuous above the crowd. The colour crests functioned as ‘attractants’ in drawing the eye. But our question is, on modern roads, do similar-coloured aids work as attractants when riding a motorcycle?

A good starting point would be to define what we would like hi-vis clothing to achieve. The term ‘conspicuity’ is used freely enough in research papers, but by the time the term filters down into the kind information available to motorcyclists, it’s become a word without a definition. It’s bandied around without us riders necessarily understanding what it means. To achieve increased conspicuity, we need to:

• increase colour and luminance (brightness) contrast
• enhance shape and thus the observer’s ability to recognise a PTW for what it is

And then we can start to break down the task more specifically.

• enhance conspicuity at a range of distances matching urban and rural speeds
• enhance conspicuity across a range of angles ahead of the motorcycle
• enhance conspicuity in urban and rural environments
• enhance conspicuity across a range of daytime lighting conditions from bright sun to dusk
• enhance conspicuity at night
• provide a ‘visual signature’ which allows the observer to recognise the vehicle as a motorcycle rather than another vehicle
• provide visual information to allow an accurate and reliable time-to-collision calculation

Suddenly ‘be safe, be seen’ doesn’t sound quite so simple does it? Nor does it seem likely that a single garment can provide for all those needs; in fact, a garment that performs well in one way is likely to be compromised in others. So we really need to start thinking about how these principles will work in the environment in which we are riding.

Let’s start with daylight conspicuity – we’ll look at night another time. Photopic vision refers to how we see in well-lit conditions – daytime, in other words. Human photopic vision not only allows us to perceive colour, but also offers a high degree of ‘visual acuity’ (ie, clarity of vision). At the time of the of the ‘Ride Bright’ campaign I was at university in London and an inexperienced rider. It seemed ‘obvious’ that bright clothing would stand out so I was an early adopter. I was one of the first riders to wear first a reflective yellow ‘Sam Browne’ belt. A few years on, when I was starting my long spell as a courier, I grabbed one of the first fluorescent Saturn Yellow jackets when they appeared on the shelves. Saturn yellow came into use for hi-vis clothing because in daylight the human eye shows greatest sensitivity to yellow-green hues.

So did it work? Initially at least, riding around London, and on long motorway runs on gloomy winter days, the yellow jacket did seem to stand out. Around 1990, I moved to Kent and did a lot more courier riding on smaller roads in rural areas. And now I realised that Saturn Yellow that seemed to stand out against traffic in the big cities didn’t produce nearly as much contrast against rural foliage on sunny days.

What I’d discovered for myself was a significant limitation of conspicuity clothing. It has to generate a contrast to be conspicuous. Although it can achieve this two ways – colour or light / dark contrast – hi-vis can only be effective if it is a DIFFERENT colour or shade to our riding environment. It’s usually the case that whenever we see photos illustrating the effectiveness of hi-vis – whether we’re looking are the illustrations below which are taken from the online Highway Code or the advertising material we saw earlier – the photos are staged to show the hi-vis material to the greatest advantage. In the case of the Highway Code, the bikes are placed in shade in front of a dark background.

That was my own thinking, but what does the research and advice say? The answer might surprise you. The 1996 edition of ‘Motorcycle Roadcraft’, the police manual actually states that what matters is “how well you stand out against the background… [which] can change rapidly”.

The advice in ‘Motorcycle Roadcraft’ may have been based on published work by Hole et al (1995), who determined that:

“…the effectiveness of the conspicuity aids used, especially clothing, may depend on the situation in which the motorcyclist was located: bright clothing and headlight use may not be infallible aids to conspicuity. Brightness contrast between the motorcyclist and the surroundings may be more important as a determinant of conspicuity than the motorcyclist’s brightness per se. Motorcyclists’ conspicuity is a more complex issue than has hitherto been acknowledged.”

Pai also noted in a literature survey published in 2011 that:

“…some researchers reported that a motorcyclist’s / motorcycle’s brightness per se may be less important as a determinant of conspicuity than brightness contrast between the motorcyclists and the surroundings.”

The Transport Research Laboratory (TRL) has recently released a couple of papers in which they reviewed the literature on visibility and conspicuity; one was aimed at motorcyclists ((Helman et al; 2012), the other for the riders of horses on roads. In both cases, the advice mirrored what was written in the 1996 edition of ‘Motorcycle Roadcraft – riders should wear high visibility and reflective clothing, but choosing a colour appropriate to the riding environment.

That really is quite a shift in understanding from the earliest advice, but it’s already two and a half decades old. Yet a recent document proposing a common colour scheme for police motorcycles still states unequivocally that Saturn yellow is the best contrast for all riding environments. This is quite clearly incorrect. It’s also rather a surprise given that advice from the 1996 edition of ‘Motorcycle Roadcraft’. Any colour will have moments when it is conspicuous, but places where where the background colour is similar, it will not show up nearly so well. The yellow hi-vis that stands out well under the trees will be far less effective once we ride out of the shady patch and are silhouetted against brightly-lit green leaves, particularly if the hedgerow is full of yellow newly-bursting spring buds or golden autumnal foliage. In town, Saturn yellow may show up against dark buildings, but the same colour clothing will vanish in front of van painted in hi-vis yellow for marketing purposes. And just how conspicuous would a Saturn Yellow wearing rider be, riding through this field of oil seed rape in full flower?

Without a strong contrast we won’t ‘leap out’ from the similarly coloured background and into the driver’s conscious awareness. Given the requirement that police bikes are recognised as police bikes, the choice of Saturn Yellow is at least partly down to a requirement for a ‘corporate livery’ and a single colour scheme across police forces. From that perspective, Saturn Yellow makes sense. But it is clearly not effective as a conspicuity aid in all riding environments.

Less intuitively, dark colours show up against light backgrounds – have another look at the advertising photo and see how the black parts of the clothing actually show up well against the light grey sky. Fair weather, daytime-flying RAF trainers are now painted black for that reason. The black elements also show up well against the road surface, which isn’t dark at all when sunlit, but a pale grey – see the lane in the photo above. Contrary to popular belief, there is evidence from several research studies that in bright sun on the open road, a black-clad rider on a black motorcycle shows up best of all, including a recent Israeli paper (Gerson et al 2012). But the light intensity changes from moment to moment too. The sun goes in behind clouds, it rises and falls in the sky, and we ride in and out of patches of deep shade under trees or behind tall buildings. The potential issues with black clothing on roads where the light intensity changes significantly should be obvious.

So what matters is not just the colour of our clothing, but whether it creates contrast with what’s behind us, and that depends on both the colour and the lightness or darkness of the background and though it’s popular, we’re not forced to use Saturn Yellow. For the rest of us, there’s some help – it’s known as the colour wheel and you’re most likely to have come across it as an aid for choosing paint colours that work well with other colours. But it can also be used to illustrate contrast. Colours that are near to each other do not create effective contrasts – for that we need the opposite colour on the wheel. You can also see the effect of luminance here – lighter shades are at the inside of the wheel.

Consider where Saturn Yellow WOULD stand out. It will certainly be effective in front of a dark background like a London black cab and performs adequately in urban areas silhouetted against buildings. In bright sun, it shows up adequately against light colours like a white van or a grey or pale blue sky. It’s also reasonably good in dull conditions and even at night because it’s a light colour. But as we’ve seen it performs relatively poorly against yellow-green foliage.

So all this was basically what I was thinking as I was riding around the leafy lanes with my parcels after moving out of London. My solution was to do something a bit radical. I bought a hi-vis pink jacket. I was still wearing that same jacket five or six years later when working as an instructor for Cinque Ports Motorcycle Training in Lydd in Kent, and riding on the flat lands of Romney Marsh. Wearing pink generated predictable hilarity but my fellow instructors admitted that it did stand out when we were riding across the Marsh. If you check the colour wheel, you’ll see why – it stands opposite green. It’s also a relatively light colour so stands out against a dark background. Of course, I’m not the only one to be a fan of pink hi-vis. Biker and all-round nice guy Danny John-Jules was at Honda’s HQ where I delivered one of my SOBS presentations in 2018 and was kind enough to send me a couple of pics of him out on his bike which I’ll feature later.

What about white, incidentally? Well, white’s not technically a colour but all colours mixed – remember the rainbow, which is what we see when sunlight is split by a raindrop. White clothing tends to ‘tint’ towards the colour of the light illuminating it. The light that passes through leaves is green (that’s why they appear that colour) and so a white garment under green leaves tends to turn green.

The need to consider our background means is that hi-vis clothing is not the ‘fit-and-forget’ solution as it’s so often presented. We cannot just stick it on and believe that we’ve increased the chances of being seen by other road users. In the past, rider safety campaigns have tended to make very bold statements suggesting riders wearing hi-vis are more likely to be seen, and thus safer. But as the research itself has become less positive about the benefits of hi-vis, there has been a recent change in advice feeding down the chain to motorcyclists! Even the Highway Code’s advice has become less definite and now says:

…be aware that other vehicle drivers may still not have seen you, or judged your distance or speed correctly…

There’s one further problem with Saturn Yellow clothing – it’s everywhere. Years back when I first started wearing hi-vis clothing, it wasn’t just conspicuous (at least, as we now know in some circumstances) but it stood out as unusual – there was a ‘wow’ factor. But take up was rapid. By the time of a 1986 national survey into the characteristics and attitudes of motorcyclists, when asked about “clothing as an aid to conspicuity, 79 per cent of riders agreed with [the] statement ‘Bikers should wear clothing which makes them easily seen'”. (Hobbs et al). I don’t have figures for current take-up, but from casual observation of other riders, it’s clear that when I wear Saturn Yellow hi-vis, I am no longer one IN a crowd, but one OF the crowd.

Having said that, the very ubiquity of hi-vis means that it has come to be associated with vulnerable road users – pedestrians and roadside workers, cyclists and horse riders all use hi-vis. That doesn’t necessarily mean that hi-vis clothing will be seen more ‘easily’ or ‘more quickly’, or even that once spotted, the driver will realise that the hi-vis is being worn by a PTW operator. But there is a chance that the other road user will understand that there is a vulnerable road user and take a second look.

I started writing about the limitations of Saturn Yellow hi-vis and the benefits of pink when I first got online in the mid-1990s. Pink does have a certain novelty about it! I put my ideas together on an early post on my ‘blog before they were called blogs’ way back in the early 2000s – you can still find that post. I’ve been delivering warnings about relying too heavily on hi-vis in my SOBS presentation on ‘Biker Down’ since 2011 (a version is delivered by many other ‘Biker Down’ teams), and in February 2018 I took the presentation to New Zealand to deliver it on the Shiny Side Up rider safety initiative.

Bit by bit, I’ve seen other writers pick up on these issues – there’s a well-known article written in 2012 for a UK cycling magazine that explores many of the issues mentioned on this site and I came across an excellent Canadian video on YouTube just the other day.

I’ve already mentioned the Highway Code, but in late spring 2018, when I attended a Metropolitan Police BikeSafe course, I was surprised to discover that hi-vis clothing wasn’t top of the list in a discussion of possible strategies. Whilst hi-vis still promoted as a good thing, the big difference was that its limitations were also discussed. The presenter explained how it needed a background contrast to work, and also suggested that the use of Saturn Yellow hi-vis has become saturated because everyone uses hi-vis yellow.

And pink got a mention. Now, I wonder where they got that from?

So if the latest advice is now less emphatic about the effectiveness of hi-vis and the limitations of conspicuity aids are being more clearly spelled out to riders, we should ask a question: is there any evidence that hi-vis clothing works?

Definitive evidence is remarkably hard to find. There are countless laboratory studies and trials that show that detection of PTWs is improved when the riders use hi-vis clothing, but if hi-vis clothing worked in practice, we’d expect to see reductions in the number of junction collisions in collision statistics from the early 1970s when riders first started to wear conspicuity clothing to the present date.

That early 1980 TRRL study I have mentioned before sent out a questionnaire to a sample of riders, asking:

“…whether or not they had experienced any accidents involving another vehicle or pedestrian in the last three months, and if so to declarea) how many accidents.b) on how many occasions they were wearing their safety clothing at the time of the accidentc) what were the causes.”

They went on to analyse the responses. In terms of actual crashes, just three involved riders reporting themselves as wearing hi-vis clothing and no less than twenty happened to riders without. As the overall usage of hi-vis clothing was 45% across the sample of motorcyclists, this appears at first sight to be firm evidence for the effectiveness of the conspicuity clothing in preventing collisions, although we could be seeing the effect of risk-averse riders adopting both a cautious approach to riding AND the conspicuity aids.

So if we assume that hi-vis clothing is equally effective at preventing near-misses and collisions, it would be reasonable to expect the same kind of pattern, with riders not wearing hi-vis having far more near-misses than those using the conspicuity aids. In fact, the distribution of reported events was totally different – 64 near-misses involved riders wearing hi-visibility safety clothing and 62 involved riders not wearing hi-vis clothing.

I think we are seeing two problems. I’ve already mentioned that we do not have any figures for those riders who experienced zero ROWVs. It’s entirely possible that novice riders adopted hi-vis, whilst more experienced riders did NOT take up the use of hi-vis clothing, had zero collisions or near-misses, and do not show up in the data. And I think we’re seeing here is reporting bias. It’s entirely possible that motorcyclists wearing conspicuity clothing were EXPECTING drivers to see them – after all, that’s what the ‘Ride Bright’ campaign in London had been telling them would happen. So in the event of a ROWV, the motorcyclist was of the opinion that the driver SHOULD have given way, and thus reported a near-miss even when there was no real threat to the rider and the gap was more-than-adequate for the driver to complete the manoeuvre. I am speculating but none of this seems to have been considered by the authors who only observed that:

“It would appear that accidents occurred much less frequently than near misses when the safety clothing was being worn.”

This is a possible consequence of ‘Ride Bright’ style campaigns – motorcyclists expect to be seen. Sager et al (2014) in a gap acceptance and lane positioning study concluded:

“…it is in the motorcyclist’s best interest to employ defensive countermeasures. Such countermeasures should not be strictly passive or static, such as the use of a headlight modulator or the wearing of a bright yellow jacket. These countermeasures, while sometimes effective, may lull a motorcyclist into a false sense of security.”

I have found only one study* that looks at actual results in terms of risk reduction. Carried out in New Zealand and published in the British Medical Journal in 2004, Wells et al suggested that wearing fluorescent and/or retro-reflective clothing was related to a decrease of approximately 37% in motorcyclists’ risk of injury; not crashing, you’ll notice. The study didn’t count collisions but investigated the consequences of crashes. Whilst they argued that the results took into account ‘confounding factors’ such as age and alcohol consumption, they do not appear to have considered the most obvious – whether or not protective clothing was being worn at the time of the collision. It would be entirely possible that riders concerned enough to wear hi-vis or reflective clothing to reduce the risk of a collision were also careful enough to be better-protected in the event of a crash.

[* If you know of others, please let me know and I’ll update this section.]

Unfortunately, the SMIDSY collision remains the most common crash in urban areas – it’s hard to see any obvious reduction in these crashes. Clarke et al. (2006) found that in more than 30% of ROW crashes in the UK where other drivers were at fault, motorcyclists were also using DRLs and/or reflective clothing. In any case, it would be hard to determine whether any reduction was due to the hi-vis clothing itself, or because it is often worn by more risk-averse riders; rather than making riders safer, it could be worn by safer riders!

So, to sum up. The use of hi-vis is far from a guarantee of ‘be seen, be safe’. It’s absolutely essential to remember the effectiveness of any particular colour varies from moment to moment, and that means we need to re-calibrate our hi-vis strategy completely: even if you are using hi-vis, don’t EXPECT to be seen!

Accept that and it’s a short step to realising that our planning process should take into account the possible need to take sudden evasive action. It’s particularly dangerous to slip into the mindset where we rely on it; as one rider wrote as a comment on one of my blog posts: “it makes me feel more confident that I’ve been seen”. The moment we think that, we’re dropping our guard.

I can’t sum up better than the authors of the TRL’s 2012 Literature Review on the topic:

“Given that environments may differ over even fairly small changes in time or location, there is not likely to be a one-size-fits-all solution, meaning that motorcyclists need to be aware of the limitations of whichever interventions they use.”

In other words, “biker THINK!”

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References:

Clarke, D., D., Ward, P., Bartle, C., Truman, W.  (2007) “The role of motorcyclist and other driver behaviour in two types of serious accident in the UK” Accident analysis and Prevention. 39 : 974-981.

Gershon, P., Ben-Asher, N., Shinar, D. (2012) “Attention and search conspicuity of motorcycles as a function of their visual context” Accident Analysis & Prevention

Helman, S., Weare, A., Palmer, M. and Fernandez-Medina, K.(2012) “Literature review of interventions to improve the conspicuity of motorcyclists and help avoid ‘looked but failed to see’ accidents” Transportation Research Laboratory, Project report No. PPR638

Hobbs, C., Galer, I, and Stroud, P. (1986) “The characteristics and attitudes of motorcyclists: a national Survey” Transport and Road Research Laboratory Department of Transport Research Report 51

Hole, G. J., Tyrrell, L. and Langham, M. (1995) “Some factors affecting motorcyclists’ conspicuity” Ergonomics Volume 38 Issue 7

Highway Code https://www.gov.uk/guidance/the-highway-code/rules-for-motorcyclists-83-to-88

Pai, C.W. (2011) Motorcycle right-of-way accidents – a literature review Accident Analysis & Prevention. 43 (3), 971–982.

Wells, S., Mullin, B., Norton, R., Langley, J., Connor, J., Jackson, R., and Lay-Yee., R. (2004) “Motorcycle rider conspicuity and crash related injury: case-control study” BMJ 2004; 328 doi: https://doi.org/10.1136/bmj.37984.574757.EE

Last updated: 

Wednesday 12 June – added information about the need for contrast from Hole et al, Pai  plus references, minor edit for clarity
Wednesday 1 May – minor edit for clarity
Thursday 17 January 2019 – added photo of rider in hi-vis orange jacket
Friday 21 December – added comment about hi-vis alerting drivers to vulnerable road users, minor re-ordering of points within the text
Friday 23 November – added self-reporting data from TRRL study
Saturday 10 November – added colour wheel
Friday 9 November – aims of conspicuity aids, Clark et al, Wells et al, Gerson et al references added
Wednesday 7 November – minor corrections
Tuesday 6 November – Highway Code info added, pink jacket photo added, rewritten for improved clarity
Friday 26 October 2018 – typos corrected, rewritten for improved clarity

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Photo credit Paul Townsend https://www.flickr.com/photos/brizzlebornandbred/20001313491