B’ Spokes: This article in Scientific American has a lot of interesting points but I would like to comment a bit about their subtitle "Traffic is easing as more Americans are deciding to drive less, sell their cars or not buy one at all"
My comment is to contrast "a 1.2 percent decline in vehicle miles traveled (VMT) last year" with "traffic congestion in the United States fell by 27 percent last year". While exactly what is cause and effect is still under consideration I still want to point out for consideration that just a small reduction in VMT results in larger relief of congestion. This is due in part because once a roadway is at the saturation point of maximum traffic the addition of just a small amount traffic cause a cascading delay effect (think of one person hitting the brakes on a crowded highway and then all those behind are now also hitting the brakes), a catastrophic failure (think grid lock but something similar happens once people have to wait more then one cycle for a light causing more and more people to wait in the queue at each cycle) or just a "simple" traffic accident (happens on average every 5 minutes in Maryland and "accidents" are the MAJOR cause of traffic delays.)
The short of it is our road designs cannot gracefully handle additional traffic above a certain threshold, they fail and they fail severely. I will assert that’s why just a small reduction in VMT will result in a larger reductions of congestion.
My point in bringing this all up is because we cannot afford to build enough roads to have congestion free driving. But we can afford to provide alternate transportation to keep travel times for all at tolerable levels. And that’s the question we should be asking, are travel times at a tolerable level and forget about congested roads (they are inevitable.) And on this point I will assert average commute travel time of around a half hour is tolerable and the "worst" of 5 more minutes* is not that big of a deal. Of course we should try and improve this but the main thrust should be on alternate transportation (not more road projects at the expense of alternate transportation) as that will yield the most bang for the buck.
The Scientific American article: https://www.scientificamerican.com/article.cfm?id=has-us-reached-peak-car-americans-driving-less
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Reference:
* Commute travel times: https://www.census.gov/prod/2011pubs/acs-15.pdf
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