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army1987 comments on How can I spend money to improve my life? - Less Wrong
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If you spend more than 20 minutes on your commute (one way), consider moving to somewhere closer to where you work. Walking distance is ideal, biking distance a good second-best. Commutes literally kill; you will not only get more time daily, but also your expected lifetime will increase.
In certain places, biking is probably even more dangerous than driving.
Seriously, citation needed; all the claims I've seen are that cycling is dramatically safer.
Mile for mile, biking is significantly more dangerous than taking a car (as is walking), though not as dangerous as riding a motorcycle. (See here, or here if you're willing to tolerate older data and worse formatting.) You're trading off for physical fitness, though, and the life expectancy gained from increased fitness -- especially if expressed in terms of QALYs -- generally outweighs that lost from increased accident risk.
This undoubtedly varies by location but I haven't been able to find any good data on how. The waters are also muddied a bit by the fact that bike advocacy organizations like to promulgate the life expectancy data without the accident data -- not that I can really blame them, statistical literacy being what it is.
The one study I've seen that looks at the net health effect of cycling came to the conclusion that cycling is a net benefit. Loads of bicycling advocates promote this to suggest that cycling is in general a net benefit for you health. Unfortunately for North Americans, the data in the study came from Europe. Cycling is much safer in Europe. I am not aware of any analysis using data from North America, and I'm unsure whether such an analysis would come to the same conclusion.
With this being said, I ride a bike for transportation. I read studies on safety and actively try to minimize my risk. This includes minimizing my mileage, as the risk is per unit distance. So far, so good. I haven't been in a real crash yet in 4 years of commuter cycling, though I've had plenty of close calls. Worst I can say is that I did once hit a pothole and fall over, but there were no lasting effects.
SF in particular has been working hard on bike infrastructure improvements that should help with safety. Especially if your commute involves Folsom St.
Morgan et all (2010) (http://www.biomedcentral.com/1471-2458/10/699/) estimate 11.1 cyclist deaths per 100000 cyclist-km in London.
Wikipedia (https://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate) estimates 8.5 road fatalities per 1 BILLION vehicle-km.
http://www.theguardian.com/news/datablog/2012/sep/28/road-deaths-great-britain-data claims 125 motorcyclists died in road accidents for every billion miles travelled - the highest rate for all road users but also a year-on-year fall of 11%.
At 41 deaths per billion miles, the mortality rate for pedestrians was just above that of cyclists (35), with the former a year-on-year rise of 10% and the latter a fall of 6%.
Car occupants had by far the lowest mortality rate at four deaths per billion miles travelled.
London is an exceptionally unsafe place for cyclists. I doubt it's anywhere near so unsafe as to make up all the difference between cycling and driving in those statistics, but I would guess it's at least 10x worse than the average, maybe quite a bit more.
... Ah, wait, I see you have other statistics saying 35 deaths per billion miles cycled, which would be about 21 per billion km, versus 11 per 100k km or 110,000 per billion km in London. So, apparently London is nearly four orders of magnitude worse than average. That's ... more than I expected. Have I misunderstood or miscalculated something?
That "11 per 100k km" figure says that if someone has a 2x5km commute in London that they do 200 days per year, they expect to die about 0.22 times per year; in other words, their life expectancy is a bit less than 5 years. I repeat, London is exceptionally unsafe for cyclists, but I think I'm going to defy the data here. Can it really be that unsafe?
[EDITED to add:] Some other figures I've seen suggest that serious injuries are maybe 20x as common as deaths. That means that my hypothetical 10km/day London cyclist should expect four serious injuries per year. Really?
There are some statistics on the Wikipedia Cycling in London page. For 2014 they report 13 deaths from 610k "daily journeys". Even if a "daily journey" is as short as 1km, that would be 13 deaths per 610k km, which is a lot less than 11 per 100k km. (Though still scandalously large.)
The paper is doing some weird things. To quote from it:
Note: cyclists per kilometre.
No, per 100k cyclists per kilometre; that is, per 100k cyclist-kilometres, which is dimensionally correct. Or am I misunderstanding what it is you find weird?
I only glanced at the paper, but my suspicion is that they are using something like 100K cyclists per kilometre of road, not per kilometre actually cycled. They admit to not knowing the miles cycled, but if you guesstimate the number of cyclists and you know the length of roads in London, you can produce a "cyclists per kilometre of road" metric. I am not sure how meaningful it is.
Bloody hell, you appear to be right. What a ridiculous figure to be publishing.
I am quite sure how meaningful it is: not meaningful at all.
Paging Tony Stark! :-)
Cyclists per kilometre of road is a measure of cyclist density. To do a proper density estimate you also need to know how long (in hours) does an average cyclist spend on the road, but conceivably you can handwave it away as a near-constant. Given this, their approach is to look at the fatalities as a function of the cyclist density.
They are still missing too many variables to produce a useful estimate, but it's not prima facie insane.
Deaths per cyclist per kilometre of road is a crazy unit of measurement. I mean, sometimes you have to report the statistic you've got rather than the statistic you'd like, but I don't see what possible practical significance this has.
The statistic we'd like to know is deaths per kilometre cycled. The average person in the UK cycles about 60 km a year (source: Department for Transport) and the population of London is about 8.5 million (source: Wikipedia), so the 19 deaths in 2006 correspond to about 3.5 deaths per 100 million kilometres cycled.
This is slightly higher than the UK average of 3.1 deaths per 100 million kilometres cycled, and on the high side for Western Europe (compare Netherlands: 1.0; Germany: 1.8; France: 3.1; Italy: 3.4).
See http://lesswrong.com/lw/awm/how_to_avoid_dying_in_a_car_crash/62jy