Discover more from Overcoming Bias
I often listen to music or use my phone while walking through town. I have heard that this is dangerous and could cause me to get killed, so I’ll attempt a back of the envelope calculation to work out if I should stop.
Firstly, the base rate of risk for being run over as a pedestrian in the UK is 0.0006% per person each year. Let’s say as a young man I face double that risk, or 0.0012%. I don’t know how much using my phone some of the time while walking raises the risk, though this data suggests a pedestrian failing to look properly was the cause of 190 road fatalities in the UK, out of a total of 385 pedestrian deaths. For the sake of argument, let’s say the risk triples. Let me know if you have a better estimate. That would result in an extra risk of death of 0.0024% each year. Dying now would cost me some 60 years of healthy life, so I should expect to lose 0.00144 years for each year I engage in this behaviour – which is around 12 hours.
As compensation, I get to listen to music, audiobooks and check my email for on average 10 minutes a day, which comes to 60 hours or so a year. I would say that time is about 50% better spend than it would be otherwise thanks to my ability to use my phone, so I expect to gain the equivalent of 30 hours a year.
If these numbers are about right, I should be fairly comfortable listening to music or looking at my phone as a pedestrian. However, the harm is pretty close to the benefit, and someone could reasonably think the cost actually outweighs the benefit.
Nonetheless I could do better by not using my phone in cases where the cost exceeds the benefit, for example by keeping the volume low, not having conversations which are particularly distracting, and being strict about not starting to look at my phone if I expect to cross the street soon after.
If you like this approach – and maybe even if you don’t – you’ll also like How to Gain or Lose 30 Minutes of Life Every Day, which estimates how much life you should expect to gain or lose each time you exercise, eat fruit, vegetables or meat, drink alcohol, smoke a cigarette, remain overweight, or sit at a computer for hours at a time. Gains and losses are measured using the ‘micromort‘, which corresponds to half an hour of life. While the numbers are no doubt a dramatic simplification of the medical evidence, I find a concrete estimate of the benefits gives me stronger motivation to eat more vegetables, drink less, and perhaps exercise more as well. And it helps me prioritise which health enhancing activities are worth the trouble, and which are not.
Should I stop using my phone as a pedestrian?
Your post is very interesting. I do like your analysis and your beliefs are similar to mine. I would add the following cautions based on my recollections of US Pedestrian Traffic Fatalities data:
1. Don't walk Drunk. One third of US pedestrian fatalities occur with intoxicated pedestrians.
2. Don't J-walk. One half of US pedestrian deaths occur in roadways where pedestrians are not designated to be. I am aware that in many of these cases it is because no pedestrian facilities are provided.
3. Be more careful on Arterial roads. I am less sure of this number but close to 40% of US pedestrian fatalities occur on arterial streets. I would add that crossing a street also requires additonal vigulance.
4. Be more careful after dark. Pedestrians don't have visibility requirements so if it is dark there is a higher chance of fatalities per mile walked.
Based on these recollections, when in the daylight and on a sidewalk there is very little added risk with headphones and walking texting/emailing.
But as an former avid runner, I would not advise running in the street unless you have full control of your sense and take full responsbility for being alive after you enter the domain of the car.
Limit your device use to cases where you can retain situational awareness. That means stopping whatever you are doing on the phone whenever you see something that you should have noticed earlier (e.g. another pedestrian) but didn't, and whenever you anticipate that you might need to react quickly to something (e.g. when you cross any street).
For music/audio, I would restrict it to one ear.
If your goal in walking is to relax, or your goal for audio is to zone out or attend to the audio, don't do it on the sidewalk or anywhere else other people have a reasonable expectation that you are situationally aware.