What do cyclists need to see to avoid single-bicycle crashes?

From a Press Release

With the ‘Wiggins effect’ in full swing after London 2012 and people taking up cycling for sport or recreation like never before, the safety of the country’s cyclists has never been more important.

Crashes are an unfortunate fact of life for many travelling on our roads and bicycle paths, but how and why they happen is not always well understood. In the Netherlands alone, A&E Departments treat 46,000 injuries sustained in single-bicycle incidents each year, 6000 of which lead to hospital admission. Reducing the number of bicycle accidents is thus good for the public purse as well as for the cyclists themselves.

Faced with such figures, two Dutch academics, Paul Schepers and Berry den Brinker, set out to learn more about single-bicycle crashes. The resulting paper, ‘What do cyclists need to see to avoid single-bicycle crashes?’, has been awarded two prestigious prizes from insurers Liberty Mutual: ‘Best Paper Published in the Journal Ergonomics’ (54/4 2011, 315¬–327) and the ‘2012 IEA/Liberty Mutual Medal in Occupational Safety and Ergonomics’.

The researchers followed two approaches. The first was to ‘study the relationship between the crashes and age, light condition, alcohol use, gaze direction and familiarity with the crash scene’ in a set of accidents. The second used the ‘image degrading and edge detection’ (or IDED) method to investigate the visual characteristics of some crash sites.

What the authors found was that in those crashes where a single cyclist collided with a bollard, narrowed road or other obstacle, or rode off the road altogether, poor visibility and especially poor visual contrast played a significant part. Schepers and den Brinker also investigated how issues with a cyclist’s ‘focal’ vision (seeing the ‘far’ road ahead to plan for future hazards) and ‘ambient’ vision (seeing the ‘near’ road to correct the bicycle’s current position) can contribute to a crash.

As a result of their study, the authors question the common assumption that cyclists ‘can do without a minimal level of guidance and conspicuity of (design-related) obstacles’.

They state that ‘the visibility of critical information in the visual periphery is indeed important for safe cycling’ and make several recommendations, including applying edge lines to the curves on bicycle paths, especially on those with high levels of cycling, no street lighting or a risk of glare from oncoming vehicles.

Schepers and den Brinker also suggest that adding warning centre lines to two-way cycle paths, increasing the visibility of bollards with contrasting colours, and using ‘profiled’ markings to alert a cyclist riding behind another to dangers ahead could all help prevent crashes.

This prize-winning study on accident prevention – which shifts the focus from road-surface issues and the visibility of cyclists to what the cyclists themselves actually see – is essential reading for urban planners, cycling promoters and anyone concerned with the safety of the thousands of people now taking to two wheels after the recent Olympics.

Read the article in full for free at: http://www.tandfonline.com/doi/full/10.1080/00140139.2011.558633

Comments

[ken]

Looks like (at this moment anyway ;-)
the url should be

http://www.tandfonline.com/doi/abs/10.1080/00140139.2011.558633

[ken]

actually - the problem is it appears there are a bunch of '-' in the href:

http://www.tandfonline.com/doi/full/10.1080/00140139.2011.558633

[rootchopper]

Edge lines is a very useful recommendation. The Mount Vernon Trail in Jones Point Park has edge lines and they help quite a bit. In contrast, the MVT elsewhere does not and it can be really hard to see where the path edge is, especially with the glare of car headlights from the GW Parkway.

[Crikey7]

This is quite interesting and helpful, but let's not totally forget about road surface issues. Poor road/path conditions, debris, grooves or path edges that are parallel to the direction of travel and similar factors cause plenty of accidents.

Those bollards? Sure, make 'em visible. But first, make sure they are even needed.

[ken]

@Crikey7 - indeed in the paper the majority (554) single cyclist accidents were due among other things to " loss of control due to bumps and holes in the road surface," as opposed to the 180 due to visual designation issues.

[MM]

It seems that the cause for most crashes, at least if my own experience is evidence, can be distilled down into one issue: MUPs, roads, and their related infrastructure are designed, built, and maintained primarily from a windshield perspective. Road maintenance, for instance, is entirely car-centric. "A few potholes? yeah, they're kinda annoying, but they won't cause a car to crash, so we'll just thrown some asphalt in the hole and move on." "Seams in the pavement? Drivers don't even notice, so what does it matter?" "Leave that milled street unpaved for a few weeks? Why not, it doesn't hurt the cars."

It makes me wonder if places like Denmark or the Netherlands have separate designers/engineers/contractors developing their cycling infrastructure...you know, ones that actually ride.

[Greenbelt]

@MM -- the larger issue is that as we continue to build highways for car-centric suburban and exurban sprawl, we have less money for maintenance of existing roads. Funds to really keep the roads clean and in good shape are sacrificed when we spend billions on superhighways like the ICC, and arguments that tax funds aren't somehow fungible or that "the money came from a different account" just don't wash.

[SJE]

Greenbelt: so true re the funding. Apparently the entire Portland bike network was built for a quarter the cost of a highway clover leaf.

[T]

Rootchopper beat me to it. Edge lines is a great recommendation. The one slight hill with sharp turn on the MVT between the marina and airport comes to mind. At night the glare of road traffic, the sharp nearly 90 degree turn (often with leaves or small twigs) and the inability to see what's ahead because of the trees makes it quite dangerous. I've nearly hit oncoming cyclists and joggers who hug the middle of the path there. I wish they either expanded the bottom of that turn to make it wider, made it a straightaway there or at least edge lines.

[NoRacer]

Most of my single-bicycle/self inflicted accidents had nothing to do with sightlines or visibility or traffic. It was simply due to mechanical issues, such as slipping a chain down on to the bottom bracket while trying to accelerate from a stop or the misalignment of the inner tube in a tire causing it to get pinched and flat (especially damning during going downhill) or a worn rim strip on the front tire inflicting a blowout at speed or the slipping a cleat out of a clipless pedal during a hard acceleration.