A 24% increase in vehicular death rates based on driving 13% less

From the National Safety Council, Motor Vehicle Deaths in 2020 Estimated to be Highest in 13 Years, Despite Dramatic Drops in Miles Driven.  

For the first time since 2007, preliminary data from the National Safety Council show that as many as 42,060 people are estimated to have died in motor vehicle crashes in 2020. That marks an 8% increase over 2019 in a year where people drove significantly less frequently because of the pandemic. The preliminary estimated rate of death on the roads last year spiked 24% over the previous 12-month period, despite miles driven dropping 13%. The increase in the rate of death is the highest estimated year-over-year jump that NSC has calculated since 1924 – 96 years. It underscores the nation's persistent failure to prioritize safety on the roads, which became emptier but far more deadly.  

That is a powerful and puzzling piece of information which I have not seen reported anywhere else.  A year-on-year 24% increase in vehicular death rate in same period when the number of miles driven falls by 13%.  

The conclusion that if we drive less, we get rusty and become more careless drivers is not in itself improbable but . . . 24%?  That seems an astonishingly large effect size.

My suspicion is that the paradox might be resolved were we to look at average driving speed.  My speculation is that while miles driven declined, traffic congestion eased significantly and that average driving speed rose markedly.  Traffic death rates are notoriously linked to average speed of impact.  For example, 

The average risk of death for a pedestrian reaches 10% at an impact speed of 23 mph, 25% at 32 mph, 50% at 42 mph, 75% at 50 mph, and 90% at 58 mph. Risks vary significantly by age. For example, the average risk of severe injury or death for a 70‐year old pedestrian struck by a car traveling at 25 mph is similar to the risk for a 30‐year‐old pedestrian struck at 35 mph.

 My city passed an ordinance back at the beginning of lockdowns, reducing the city speed limit from 35 mph to 25 mph.  I did a post, Look both ways and hold onto to your wallet, back in May on the improbability that this would have much or any impact but at a great cost and with markedly reduced quality of life in the city.  

It would be very interesting to see someone do some deeper analysis on the NSC argument.  I would not be surprised if the increase in the death rate might be concentrated among those already the least accustomed to frequent driving, i.e. learners/the young and among the elderly intermittent drivers.  But that is speculation.

Is it possible that less used vehicles are less well-maintained cars?  Possible, but I would suspect that not to be a significant contributor to the increased death rate.

Is it possibly a class issue?  The thought here might be that the decline in driving has been among those well-off, professionals, etc.  That those fitting the bill of "essential workers", i.e. retail workers, day laborers, food and agricultural workers, public transit workers, etc., might have either worse driving habits and/or cheaper cars with fewer safety features.  Again, possible, but that seems improbable to have such a large causal effect.  

For the time being; a mystery.

As a side note, the National Safety Council is a non-profit NGO, one of those well intentioned enterprises with solid intentions which can get badly distorted.  

In this instance, the mystery of the 24% increase is ghoulishly exploited by NSC for fundraising purposes for their central mission.

With the alarming picture painted by these data, NSC is urging President Joe Biden and Transportation Secretary Pete Buttigieg to commit to zero roadway deaths by 2050 – a call NSC and more than 1,500 other organizations and individuals made in January in a letter to the new administration.

"It is tragic that in the U.S., we took cars off the roads and didn't reap any safety benefits," said Lorraine M. Martin, president and CEO of the National Safety Council. "These data expose our lack of an effective roadway safety culture. It is past time to address roadway safety holistically and effectively, and NSC stands ready to assist all stakeholders, including the federal government."

And look at that mission -  zero roadway deaths by 2050!  A callously impossible achievement.  It sounds alluring but would be impossible to achieve at all and the cost of approaching zero would be impossibly prohibitive, not least in loss of freedoms and choice.  It is an appeal for absolute government control of all things vehicular.

Traffic is just another complex system and vehicular death rates are the product of the intersect of many loosely connected related systems.  As with any set of loosely related, self-evolving, chaos manifesting,  complex systems, all progress is about better and worse trade-offs.  

We can design better safety features into cars which reduces death rates.  But when we do that we make cars more expensive and reduce access and availability of cars to a greater and greater proportion of the population, exacerbating class tensions.  Should only the wealthy drive while everyone else takes public transit (where that is is even feasible)?  It is a trade-off, and the NSC goal of zero deaths drives us towards an answer of yes.  Yes, in order to reduce vehicle deaths to zero, we should establish a society with sharper and steeper class privileges.

I am sure Zero Roadway Deaths is a great marketing slogan for raising funds.  But it is a dangerous mode of thinking, dangerous because it encourages both ignorance and authoritarianism.

UPDATE:  I have a post from back in May looking at the origins, achievability, and outcomes from the Vision Zero movement.  

I see there is reporting on this in Marginal Revolution and the commenters are having a spirited but empirically robust conversation around the issues I mentioned.   There is particular derision among the commenters for the ignorance behind the Zero Roadway Deaths goal even though there are a few trying to make the case for it as a valid objective.  The champions of informed trade-off decision making based on empirical cost-benefit analysis seem in the strong majority and with much better arguments.  

Among the commenters is the ever-reviled Steve Sailer whose is modus operandi is to wander into arguments with a Sheldon Cooper-like commitment to rational-empiricism which leads him to conclusions which exothermically react with Critical Theory and Social Justice religious positions.  Much as the languorous of mind may hate him, he does a lot of empirical reporting which mainstream journalist either cannot do or will not do.  He has a post on the 24% topic which has several elements of the analytical deep dive I was calling for the MSM to do.