This makes sense, but going this direction gets pretty tricky. A trip that you could plausibly take public transit for is probably also the kind of relatively slow urban commute that is unlikely to result in a fatal crash. For example, I live in Somerville MA, and checking FARS we have had one car crash that was fatal to someone in the car in the last decade. [1][2]
I can’t easily find numbers on how many car trips people in Somerville took over the last decade, but back of the envelope: 80k people * an average of one car trip per day * 365 days * 10 years = 290M trips. So 0.3 per 100M Somerville MA trips? (Which is also perhaps the most literal interpretation of the “where you live” in the original tweet?)
[1] This excludes car crashes where the only fatalities were pedestrians, which I don’t like but I think is the right way to do this analysis?
[2] Going back farther there used to be a lot more. I think this is a combination of safer cars and traffic calming?
One trip per day seems very low, don’t people usually do at least two trips per day (going to work, going back home), or even 4? Are trips bi-directional (in which case I must apologize, this would be a misunderstanding on my side)?
None of this is to discourage your request that such claims be supported by sources, as a standard.
One trip per day seems very low, don’t people usually do at least two trips per day (going to work, going back home), or even 4? Are trips bi-directional?
I was counting a trip as one direction: if I take the subway to work that’s one trip, and then another when I come home. But a lot of trips won’t be car trips, and everyone has a commute, and not everyone goes out every day? So I was guessing this would average to one car trip per person per day? Though thinking more now that’s probably too low?
This makes sense, but going this direction gets pretty tricky. A trip that you could plausibly take public transit for is probably also the kind of relatively slow urban commute that is unlikely to result in a fatal crash. For example, I live in Somerville MA, and checking FARS we have had one car crash that was fatal to someone in the car in the last decade. [1][2]
I can’t easily find numbers on how many car trips people in Somerville took over the last decade, but back of the envelope: 80k people * an average of one car trip per day * 365 days * 10 years = 290M trips. So 0.3 per 100M Somerville MA trips? (Which is also perhaps the most literal interpretation of the “where you live” in the original tweet?)
[1] This excludes car crashes where the only fatalities were pedestrians, which I don’t like but I think is the right way to do this analysis?
[2] Going back farther there used to be a lot more. I think this is a combination of safer cars and traffic calming?
I agree with you that this gets pretty tricky.
One trip per day seems very low, don’t people usually do at least two trips per day (going to work, going back home), or even 4? Are trips bi-directional (in which case I must apologize, this would be a misunderstanding on my side)?
None of this is to discourage your request that such claims be supported by sources, as a standard.
I was counting a trip as one direction: if I take the subway to work that’s one trip, and then another when I come home. But a lot of trips won’t be car trips, and everyone has a commute, and not everyone goes out every day? So I was guessing this would average to one car trip per person per day? Though thinking more now that’s probably too low?
Honestly I don’t really know