Road Safety News
 

Cycling: study shows safety benefits of hi-vis clothing

Tuesday 5th September 2017


Image: TfL via Flickr

The results of a new study suggest that cyclists are more than 50% less likely to be involved in a collision with a motor vehicle when wearing high-visibility clothing.

Described as the the first randomised controlled trial (RCT) looking at the safety effect of hi-vis clothing for cyclists, the Danish study compared the number of self-reported accidents for two groups - one group (3,402 cyclists) wearing yellow hi-vis (pictured below) and the other without (3,391 cyclists) - over a one-year period.

The study set out to test the hypothesis that ‘the number of cyclist accidents can be reduced by increasing the visibility of the cyclists’.

In total, the ‘accident rate’ (accidents per person per month) was 47% lower among those wearing a hi-vis jacket - rising to 55% when it comes to collisions involving cyclists and motor vehicles.

The safety effect was greater in winter (56%) than in summer (39%), and also greater in daylight hours (51%) than overall (47%).

The study was non-blinded*, and the number of reported single accidents (involving no other vehicle or individual) was significantly lower in the test group than in the control group.

The researchers, from the Traffic Research Group at Aalborg University, say this is likely to be a result of a ‘response bias’, since the hi-vis jacket was not expected to affect the number of single accidents.

To compensate for this bias, a separate analysis was carried out which reduced the effect of the jacket from 47% to 38%.

*A blind — or blinded — experiment is one in which information about the test is masked (kept) from the participant, to reduce or eliminate bias, until after a trial outcome is known. In this study the participants knew what was being tested, and as such it was a ‘non-blinded’ study.


Category: Cycling, Research.

 

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That's the point that I was making Pat. That at night the yellow doesn't show very well and the illuminating stripes only work if in the direct plane of the headlight shining on them. Even with dipped headlights unless the road surface is wet and that throws up the light from the road onto the rear of a cyclist it doesn't work. If one was to be at say a road junction, one that is unlit or even poorly lit and looking left then in many cases the illuminating tape is of no value whatsoever. If however you are following a biker then being within the same plane and the light thrown on it is particularly high enough then illuminating strips can work well.

I say this with having over 50 years of experience riding two wheeled vehicles and being heavily involved in the safety of motorcyclists for at least the last 20 years. This matter has been debated for at least that length of time when conspicuety and hi vis was first mooted as a be all and end all road safety intervention. It isn't but its useful. I make this point as riders should never presume that just because they are wearinbg hi vis that they will be seen.
Bob Craven Lancs

Agree (3) | Disagree (0)
+3

I'm not sufficiently engrossed in the subject to look up the Danish study but perhaps it would help to move the discussion away from the generic hi-viz term to “fluorescent for daytime visibility, reflective for night”.

The jacket in the picture does not seem to have much in the way of reflective stripes and if that is so, it would be of limited night time value.
Pat, Wales

Agree (5) | Disagree (1)
+4

Unbelievable - have you ever driven at night Bob? To compensate for the lack of 'active sunlight', I am sure you will have used your headlamps, either dipped or main beam as appropriate and which will have picked out anything with a retro-reflective finish whether hi-vis clothing or traffic signs. So distinct and noticeable are they, that you cannot miss them - which is the whole point.
Hugh Jones, Cheshire

Agree (10) | Disagree (2)
+8

High vis is about a useful as an ashtray on a motorcycle during dark hours where there is no active sunlight to shine back into the eyes of the driver close by. Even then if it has reflective stripes they are only of value if the light hitting them is in an extremely close proximity and almost on the same plane as the recipient. Within maybe 15 deg, otherwise it won't reflect back into the eyes at all.

Further during evenings, night and in winter, particularly when wet where there are many other light sources hitting the driver's eyes, that high vis can just blend into the background and act something like camouflage actually working against the safety of the biker.

Ther have been many many studies on this subject of conspicuety since the 1970s and none have shown the benefits that this study has so I would take it with a pinch of salt, particualarly if it's being paid for by an interested party.
Bob Craven Lancs

Agree (8) | Disagree (5)
+3

The close passing you referred to Richard.. was that at night or daytime? Please don't tell me that there are some cyclists who would not wear hi-vis at night! If that is the case, and it is for rear of close passing, do they also remove their compulsory reflectors and lights?
Hugh Jones, Cheshire

Agree (2) | Disagree (14)
-12

Actually Hugh it's quite a contentious issue with many cyclists. Some UK studies have suggested that cyclists wearing high-viz are prone to more close passing and this proxy for risk has been used to disclaim any benefits. I was very impressed by the study as there are very few RCT trials carried out in our profession, largely due to unsuitability - but also cost.

I imagine a lot of clothing manufacturers will be jumping on this evidence to help promote the use of their gear.
Richard Owen

Agree (23) | Disagree (1)
+22

Thank goodness for these studies - who would have guessed that cyclists wearing hi-vis clothing would be more visible to motorists and as a consequence would be less likely to be hit by a vehicle? There's a clue in the phrase 'high-visibility clothing'. Did it really need a 'hypothesis' to be tested?
Hugh Jones, Cheshire

Agree (4) | Disagree (26)
-22