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Tom Fairchild, of Arlington’s Mobility Lab, asked recently about the “Health Effects of Driving”.  A simple question with a complex answer that really depends on where you are vis-a-vis traffic. The health effects of traffic are much different depending on if you are a driver, a passenger, a neighbor of a road, a transit user, a walker, a biker, a resident of the metro, or the environment at large.

To start, let’s look at the driver and the passenger in traffic.  Both are really passengers, of the transportation mode traffic, though one has a much more active role in being in traffic.  If we commonly say someone is “riding” a bike, then we can commonly say someone is “riding” traffic.  The correct term would really be “driving” a bike, and “piloting” a car in traffic.

Anyway, the physical act of being a passenger in traffic consumes 5 calories per mile, at the average speed of 31 MPH. Mean trip length is 10 miles, even though the median trip length is 3 miles.  So the average car trip burns 50 calories for each passenger. The average is skewed by the fact that the 3% of trips over 50 miles account for 30% of the miles traveled.  Traffic is great for long distances.    Strikingly similar to the average calories burned watching TV, but in a nicer chair.  So, as exercise, being a passenger in traffic is not going to help muscle tone.  Unless you happen to have a large transmission in your vehicle.

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The death toll of traffic, as a rate of various population and economic characters.  Overall traffic fatalities used here, not just passengers of traffic.

The most obvious health risk of traffic is injury or even death.  Traffic is the leading cause of death for Americans aged 5-34, and is in the top two accidental causes of death from  birth to age 85.  The only thing that keeps this from being incredibly macabre is that American death rates are so low in middle age. Normalized most ways, the news is getting better all the time.  Per capita, per mile traveled and even per GDP, traffic is getting safer all the time.  Curiously, it is not getting safer  per road mile built.  The more roads we build, the more people die.

AgeDeathRates

Percent of deaths, and rank among all deaths and accidental deaths for different age groups in traffic.

There is a health effect of driving that is less well known  and irregularly documented, the stress of collision.  Driving in traffic is a high stakes game mediated by the studious and consistent application of signs and marking.  The cartoon of driving in traffic is meant to satisfy driver expectation into a safe set of habit rails for hundred of millions of traffic trips every day.  Stripes and markings notwithstanding, the prospect of collision several times every minute and the responsibility of keeping the car on the road does take its toll on the pilot.

It is hard to find data on cumulative health impacts over a lifetime, however.  They are confounded with a lifetime of enough wealth to afford a car, among other things.  The hypothesis is simple, but testing it is hard.  More on this later.

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