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> Adding in a new road can actually increase traffic as it ends up encouraging more people to drive who otherwise wouldn't have. You're alluding to "induced de

> Adding in a new road can actually increase traffic as it ends up encouraging more people to drive who otherwise wouldn't have. You're alluding to "induced demand," which does not claim that adding a new road increases traffic. When it becomes "cheaper" (in terms of time) to drive, more people will start driving, but the cost of driving (time to get from A to B) still goes down. This is basic economics, except with time instead of money. Adding a new road is a positive supply shock, which causes demand to rise until equilibrium, but the new price is going to be below the old price. See: https://youtu.be/6dwSIO_Slhc?t=236 https://youtu.be/6dwSIO_Slhc?t=236, except imagine the supply shock is in the other direction.

imtringued 5y ago
The problem with wider roads is a shift away from walking, cycling, public transport to car driving but that isn't what the comment complained about, considering the car (the single family home) is already there and anything you do can only increase efficiency. Building apartments it is the exact opposite and can only help over the long term.
slg 5y ago
Your logic is present in a lot of economic thinking, but it is flawed as it assumes people are purely rational actors that make decisions at the margins. That is a classic Economics 101 assumption that turns out to only be true in theory. In reality people are stubborn. We chase sunk costs and we repeat inefficient behavior because it is habit. People therefore won't necessarily choose to drive based on an evaluation of that individual trip. They will base it on things like whether they own a car, whether they have an unlimited pass for their local mass transit system, and simply what they did the last time they made the same trip. Therefore traffic can actually exceed where it was before as new and improved roads can lead to people buying more cars and people being less reliant on public transit.
- tylerhou 5y ago
  You're right that basic econ doesn't always hold, but in practice, it often does. In this case we actually have data on how road expansion affects transport times, which show that transport times slightly drop (as econ 101 predicts). https://www.thecgo.org/wp-content/uploads/2020/10/Can-We-Build-Our-Way-Out-of-Urban-Traffic-Congestion.pdf https://www.thecgo.org/wp-content/uploads/2020/10/Can-We-Bui... (Pages 8-10)

imtringued 5y ago

The problem with wider roads is a shift away from walking, cycling, public transport to car driving but that isn't what the comment complained about, considering the car (the single family home) is already there and anything you do can only increase efficiency. Building apartments it is the exact opposite and can only help over the long term.

slg 5y ago

Your logic is present in a lot of economic thinking, but it is flawed as it assumes people are purely rational actors that make decisions at the margins. That is a classic Economics 101 assumption that turns out to only be true in theory. In reality people are stubborn. We chase sunk costs and we repeat inefficient behavior because it is habit. People therefore won't necessarily choose to drive based on an evaluation of that individual trip. They will base it on things like whether they own a car, whether they have an unlimited pass for their local mass transit system, and simply what they did the last time they made the same trip. Therefore traffic can actually exceed where it was before as new and improved roads can lead to people buying more cars and people being less reliant on public transit.

tylerhou 5y ago
You're right that basic econ doesn't always hold, but in practice, it often does. In this case we actually have data on how road expansion affects transport times, which show that transport times slightly drop (as econ 101 predicts). https://www.thecgo.org/wp-content/uploads/2020/10/Can-We-Build-Our-Way-Out-of-Urban-Traffic-Congestion.pdf https://www.thecgo.org/wp-content/uploads/2020/10/Can-We-Bui... (Pages 8-10)