TRL - Literature review of interventions to improve the conspicuity of motorcyclists and help avoid 'looked but failed to see' accidents
while not directly focused on bicyclists, this study is still relevant in the mandatory hi-viz debates that are popping up.
Here's the "sound-bite" highlights from the report that caught my attention, along with some comments...
* "The lowest priority for validation [ie, the study suggests this is not worth looking into as a serious recommendation] would appear to be the use of high-visibility jackets and other clothing. The literature suggests that these are generally effective, but in principle (unlike lighting interventions) they do not appear to offer the same day and night effectiveness; even reflective materials require car headlights to be shining on them to be effective at night, and this is not always the case in practice at junctions, especially when car headlights are dipped."
* "When the findings from Hole et al. (1996) and Rogé et al. (2011) are also considered [in addition to Gershon et al. (2012], the message seems to be that the most conspicuous outfit will be dictated by the lighting conditions and local environment at the time, which may be extremely variable within the confines of even a fairly short ride."
* "Again at the furthest viewing distance on the urban traffic circle the white jacket was best (although not significantly so for detection times under search conditions), and on the rural road the black jacket was best. [...] The results [Gershon et al. (2012)] are interesting in that they show the previously held assertion that a bright reflective jacket will improve rider conspicuity may not always be true."
* "Interestingly the data from this study [Hole et al. (1996)] showed that plain dark clothing was more conspicuous against a light semi-rural background, but also against an urban background."
* "Although most studies reviewed show benefits of bright clothing, dark clothing may be better if the background is also brightly coloured. In line with the underlying mechanisms proposed, higher contrast with background surroundings to enable better visibility, search conspicuity, and attention conspicuity would be beneficial. 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."
* “The level and significance of the benefits afforded by conspicuity aids varied between the sites at which they were tested...It is not possible, on the basis of the work described, to recommend the use of a single aid to conspicuity which might be expected to be effective in all circumstances...the use of even...effective aids is by no means a guarantee that a motorcycle will be seen in all circumstances” (Donne & Fulton, 1985, p13).
* "There are limitations to all interventions, not least because conspicuity typically depends on a high visual contrast with the background, and this can vary from situation to situation."
* "[Hole et al. (1996)] illustrates the need to consider any conspicuity aid (in this case a measure of search conspicuity) as situational; since the key underlying factor that seems to determine conspicuity is contrast with a background, the usefulness of a conspicuity aid will vary with background."
* "Another development in the field has been an appreciation of the role of aspects of conspicuity other than visibility. For example, Brooks and Guppy (1996) found that car drivers who had relatives who rode a motorcycle were less likely than average to be involved in a collision with a motorcyclist; one suggestion for this effect is that for these drivers, motorcyclists are more ‘cognitively conspicuous’ (i.e. expected). Recent data from Crundall, Crundall, Clarke and Sharar (2012) are also relevant here; car drivers who also have experience as motorcyclists look in different places for motorcyclists at junctions when compared with other experienced car drivers and with novices. Again the suggested mechanism for this is that their experience as motorcyclists gives them an appreciation of where to look, and this ‘cognitive conspicuity’ aids detection." -- This is consistent with both the "safety in numbers effect" and that bicycling safety can be improved simply by making it "normal", accessible, convenient, and something people can do with little fuss (eg helmets and hi-viz). When motorists, their friends and their families ride cycles, they are more alert to the presence of cycles.
* "This finding [Langham (1998)] is important in that it demonstrates two things. First, that there are individual differences in the ability to detect stimuli in complex traffic scenes, even when they are being searched for directly; ‘one-size fits all’ solutions are thus unlikely, especially in very challenging viewing environments (such as cluttered backgrounds and long viewing distances [eg urban vs rural settings])."
* "[Fulton et al. (1980)] illustrates that measures that improve visibility may not always contribute to changes in behavioural responses seen at junctions." -- Hi-viz doesn't address SMIDGAF.
* "In addition, the acceptability of specific interventions to motorcyclists is an issue to be considered, especially when trying to understand the likely public health benefits." -- Similar to bicycle helmets, even if it looks good on paper, there are often unintended consequences of "mandatory use" that outweigh any benefits to society, overall.
* "Important caveats on the ubiquity of interventions all make theoretical sense in that they rely on limitations as to the actual contrast differences obtained in some settings (for example a light colour of clothing on a light coloured background)."
* "Findings such as those of Gershon et al. (2012) and Hole et al. (1996) have shown that those conspicuity interventions that are most effective vary with different background contexts; this is entirely compatible with the theoretical underpinnings of the way conspicuity works (see Section 3.1)."
* "[Aitken et al. (2012), Wellington, NZ] identified some positive [motorcycle] rider attitudes towards high-visibility clothing but that the common barriers given to wearing the clothing were image, cost, practicality and availability. They also found a prevailing attitude that high-visibility clothing does not improve safety and that it is the other road users who are at fault. Some interviewees described such clothing as ‘uncool’ and ‘non-professional’, and that such gear was not thought socially acceptable."
* "Seven segments [of motorcyclists] were derived from the interviews [Christmas, Young, Cookson and Cuerden (2009)]. These were ‘riding hobbyists’, ‘performance disciples’, ‘performance hobbyists’, ‘look-at-me enthusiasts’, ‘riding disciples’, ‘car aspirants’, and ‘car rejecters’. The segments differed in terms of their attitudes to safety gear (as well as in other ways) and the authors conclude that ‘motorcyclists’ should not be considered as a single entity when any safety intervention is to be proposed, with a wide range of interventions and strategies likely to be needed according to the rider segment identified as the target audience." -- This is similar to the heterogeneity of bicyclists. Some types of bicyclists happily wear hi-viz, while others would just give up riding if hi-viz was compulsory.
* "Riders should be made aware of the inherent limitations of any aid to visibility or conspicuity; special attention should be paid to making riders aware that there is no ‘one-size-fits-all’ solution (for example because of different contrasts with backgrounds) and that even if they have been seen by a car driver waiting at a junction, this does not mean that the car driver will have appraised their approach speed accurately (especially at night)."
* "During the period of time when reviewing the draft, Cris [Burgess] was riding his motorcycle to work and was struck from behind by a bus. Thankfully, Cris sustained only minor injuries in the collision. The irony of the fact that at the time of the collision he was wearing a bright orange high-visibility jacket, and riding a motorcycle with daytime running lights, is not lost on the authors."
* "Official casualty data from New Zealand in 2010 showed that there were nearly twice as many fatal junction crashes involving motorcycles on rural roads as there were on urban ones (11 versus 6). However, there were more than six times as many serious and slight injury accidents involving motorcyclists at urban junctions as there were at rural ones (158 versus 24, and 307 versus 48 respectively)." -- This is similar to the distribution of fatal/non-fatal bicycle crashes in rural/urban environments.
* "If the focus is to be on reducing fatal accidents, then targeting rural locations would be preferred although it should be noted that, in statistical terms, the numbers of fatal accidents are small and are likely to be subject to wide variation on a year by year basis." -- This is similar to my comments made in my submission at the coroner's Wellington Hearing, June 2012.