Human factors and cycling safety

The other day my husband Rich told me how the wing-mirror of an overtaking bus came uncomfortably close to his head on his cycle ride home, fortunately without making contact. My initial relief that Rich was safe was quickly overtaken by a sinking feeling that maybe next time we wont be so lucky, after all this wasn’t the first time he had told me of such a near miss. It would be easy to simply blame the bus driver for being careless. But this would neatly draw a line under the incident, missing the opportunity to learn from it, and potentially change things for the better. So what factors might increase the likelihood that this kind of incident will happen?

Twice Rich was involved in an incident on the same stretch of road, the railway bridge in Cosham, so how might road design be a contributory factor? The section of road in question is artificially narrowed with the use of ghost islands, squeezing oncoming vehicles together. Conversely, due to the rise of the bridge, visibility of oncoming traffic is impaired, reducing the likelihood that vehicles would stray too close to the double white centre lines. On either side of the road, next to the ghost islands, instead of there simply being a curb and then the pavement, there are high concrete blocks. This creates a road with plenty of hazards for drivers to process and navigate, and not much space, a situation exacerbated when larger vehicles, like buses, use the road.

For a cyclist, the bridge presents one of the few inclines available in Portsmouth, a prospect that some would relish, but that many would feel the strain from and that might impact their ability to maintain a steady course, particularly near the top, where the road is narrowed. The concrete blocks are a particular hazard to exposed legs, and they prevent any easy escape to the pavement. Cyclists either ride on the ghost islands, which are bumpy, and cluttered with the general array of dirt and debris associated with the untrodden edge of a busy road, making them a slippery place to ride; or they lawfully stick to the main tarmac, leaving them closer to the traffic.

I don’t have any figures about accidents on this stretch of road, or how often cyclists think traffic passes them uncomfortably close, or indeed how many cyclists take to the pavement to avoid it altogether. But it makes me think that this kind of road design will put people off cycling, and may encourage accidents.

Of course, other factors may contribute to the occurrence of vehicles overtaking too close. Maybe an over familiarity with the route can lead to over-confidence and disregard when passing cyclists. Maybe the pressure to keep to the timetable encourages bus drivers to pass bikes in less than ideal places. Could the time of day impact overtaking behaviour, with the pressure of rush hour traffic and more, potentially disgruntled, passengers? What influence does an upcoming break or end-of-shift have on driving behaviour, concentration and attention on the task of driving?

Now I am in no way trying to absolve drivers from their responsibility to drive considerately (just as I am not suggesting that all cyclists are model road users). However, by understanding potential factors that might influence driving behaviour organisations could, for example, take measures to minimise any real or perceived pressure, and can use such information when designing shift patterns.

I am not an expert in the human factors of road safety (see these guys if that’s what you’re looking for), and it would be easy to dismiss this as idle rambling, but accidents of this type do happen. Last summer, James Cracknell was undertaking an endurance challenge in America for the Discovery Channel when the wing mirror of a petrol tanker hit the back of his head.

I have to stress that I do not know if there has been any investigation into this accident or whether any causal factors have been identified, and that my thoughts outlined below are merely conjuncture. So please comment if you have details.

Cracknell’s bike was ‘lit up like a Christmas tree’, so why did the petrol tanker driver not see him? The accident took place at about 5am, which might suggest that the driver was tired from driving all night, or maybe they had just started their shift and were not fully switched on. Was the driver ill, stressed, or distracted?

Or perhaps there were more complex factors involved, for example, did surrounding light sources mean James Cracknell’s bike lights were less distinguishable? Could the tanker driver’s previous experience of the road, and driving at that time of day, mean they would not have expected to encounter a bike, and how might that have impacted on their perception of the road, and surroundings ahead of them? If these factors did contribute to the accident, then this might help further the design of products that improve cyclist visibility, or could improve understanding about the best products to use in certain conditions.

What about the petrol tanker itself: how easy is it for the driver to maintain good visual contact with a cyclist whilst preparing to and actually overtaking them from such a large, high vehicle? Are there blind spots that prevent visibility? How can wing mirror design be improved to minimise opportunity for impact, or in the case of collision, to reduce trauma?

In a perfect world drivers would only overtake cyclists when it is safe to do so, and roads would be safer by simply saying ‘drivers must try harder’. However, we do not live in a perfect world, and as humans we are fallible both in our own behaviours, and in the environments we create for ourselves. Understanding the human factors behind incidents can go some way to help minimise them, or reduce their impact when they do happen.

Just keep wearing those cycle helmets.


2 responses to “Human factors and cycling safety

  1. Pingback: Cyclists can’t win | Emma Boakes

  2. Thank-you. These are very interesting and thoughtful posts. I think it’s extremely useful to think about bike safety from a human factors perspective.

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