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General Science / Re: Why does building more roads lead to more congestion?
« on: 27/06/2017 22:30:51 »
Actually, this is a reasonably well-studied type of problem. One of the first times this has been described was by Jevons in the 19th century. https://en.wikipedia.org/wiki/Jevons_paradox
Basically, all the economists in England thought the price of coal would decrease because of recent technological breakthroughs that dramatically improved the efficiency of coal burning. Their thoughts were along the lines of "If a business can get the same amount of productivity (value) from less coal, wouldn't they decrease their coal demands to minimize the cost associated with maintaining the same level of productivity?" Turns out, no! Flip that around "same value from less coal" means "more value from same coal" coal is more valuable and therefore more expensive. Companies would be wise to consume the same amount of coal (or more) and increase their output (and that's what they did).
In special conditions this same approach is valid for thinking about road congenstion:
https://en.wikipedia.org/wiki/Downs%E2%80%93Thomson_paradox
Essentially, by making street-driving more efficient then people can get more productivity per mile driven (think more direct routes). By the same logic as the "more productivity per pound of coal used" leads to more coal being used, "more productivity per mile driven" leads to more miles being driven. If this doesn't change the number of people driving (which I think is often a poor assumption, and why this effect is less pronounced than the Jevons paradox), then same number of people each driving more miles per day leads to more congestion.
Basically, all the economists in England thought the price of coal would decrease because of recent technological breakthroughs that dramatically improved the efficiency of coal burning. Their thoughts were along the lines of "If a business can get the same amount of productivity (value) from less coal, wouldn't they decrease their coal demands to minimize the cost associated with maintaining the same level of productivity?" Turns out, no! Flip that around "same value from less coal" means "more value from same coal" coal is more valuable and therefore more expensive. Companies would be wise to consume the same amount of coal (or more) and increase their output (and that's what they did).
In special conditions this same approach is valid for thinking about road congenstion:
https://en.wikipedia.org/wiki/Downs%E2%80%93Thomson_paradox
Essentially, by making street-driving more efficient then people can get more productivity per mile driven (think more direct routes). By the same logic as the "more productivity per pound of coal used" leads to more coal being used, "more productivity per mile driven" leads to more miles being driven. If this doesn't change the number of people driving (which I think is often a poor assumption, and why this effect is less pronounced than the Jevons paradox), then same number of people each driving more miles per day leads to more congestion.
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