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What is the effect of traffic on public health.  By public, I mean people who are out in public, showing their faces, like walkers and bikers, not “public” as in collective population, or traffic, as in those moving through and to all of our places in cars, trucks and SUVs.

This is not an easy question to answer.  Not because studies haven’t been published, but that those studies are mostly on the supreme measure of health: getting killed.  If there is research on the stress effects of driving in traffic, is there also work on the stress effects of walking next to traffic, or biking in traffic?  There is, but for expediency’s sake, I’ll revisit this article later to add links.  It’s Wednesday afternoon, already.

As before, I am not as interested in the risk of a rare and catastrophic injury or death that is so well documented, at least when it happens after being hilt by a car.  I am more interested in the stress, anxiety and behavior that request with they death in mind.  If driving is the most stressful thing we do, how stressful Is walking or biking next a street full of traffic, each vehicle large and fast enough to kill us with a simple, careless twitch of the steering wheel?

As always, children are more susceptible to death from traffic than adults, because they do no t know the ways of the road.  The awful reality that they are trapped on an island in a sea of traffic has not yet sunk in.  Though they do get killed more often than adults because of their nonchalance.

Designing sidewalks to be stress free is not as simple as wide and far away from the street.  As I’ve mentioned before, sometime a street can be com;eye without sidewalks, if the traffic is light, slow and wary enough.  If the sidewalk is placed too far away from the road, or not at all, traffic speeds along heedless of walkers, and walkers know their place in this scheme.  They have none.  Especially pleasant is the guardrail behind the sidewalk, with the implicit message that the safety of traffic is more implicit than the knees of walkers.

Another concern for the biker and walker of traffic is air, noise and risk pollution.  This is of course greatest where the cars are, like arterials, parking lots and anyplace there is a lot of stop and go traffic.  Though freeways and  arterials do carry more traffic than other roads, they can sometimes emit fewer air  pollutants than local and connector roads.  Traffic emits most of its noxious pollutants in the first mile of every journey, as engines warm up and pollution controls take over.  The most polluting highways in America are freeways during rush hours, however, as the stop and go traffic on these congested regional highways continually accelerate and decelerate.  

Noise and risk pollution is higher on high-speed, high-volume arterials, however.  One of the great ironies of traffic is “induced traffic”, the principle that a 10% increase in arterial capacity will be met by a 9% increase in traffic *within the first year*.  This only makes sense, as relieving the congestion pressure from a popular arterial will induce more traffic to use that arterial.  This makes many highway expansions seem pointless, even though they have improved the ability of the network to move traffic by one (1) lane.  The traffic on surrounding roads gets better.  This is a bum deal for the neighbors of the expanded road, however, as they have endured a year of construction diversions and noise, all for the benefit of even more traffic in their front yards.

Finally, some wags might say that the decreased density over the last century has led to mrs for walkers and bikers, since they have to move longer distances to get to anything useful n this landscape.  While this is likely the case for those too poor to afford a car or the very rare few dedicated to biking no matter what the risks, the more likely effect of making biking and walking so inconvenient that that most people will scrimp and save to buy a car instead.