Casey Handmer did a bunch of transport economics when he worked at Hyperloop:
Let’s not bury the lede here. As pointed out in The Original Green blog, the entire city of Florence, in Italy, could fit inside one Atlanta freeway interchange. One of the most powerful, culturally important, and largest cities for centuries in Europe with a population exceeding 100,000 people. For readers who have not yet visited this incredible city, one can walk, at a fairly leisurely pace, from one side to the other in 45 minutes.
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There are thousands of cities on Earth and not a single one where mass car ownership hasn’t led to soul-destroying traffic congestion.
Cars are both amazing and terrible:
Imagine there existed a way to move people, children, and almost unlimited quantities of cargo point to point, on demand, using an existing public network of graded and paved streets practically anywhere on Earth, in comfort, style, speed, and safety. Practically immune to weather. Operable by nearly any adult with only basic training, regardless of physical (dis)ability. Anyone who has made a habit of camping on backpacking trips knows well the undeniable luxury of sitting down in air-conditioned comfort and watching the scenery go by. At roughly $0.10/passenger mile, cars are also incredibly cheap to operate.
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Some American cities have nearly 60% of their surface area devoted to cars, and yet they are the most congested of all. Would carving off another 10% of land, worth trillions in unimproved value alone, solve the problem? No. According to simulations I’ve run professionally, latent demand for surface transport in large cities exceeds supply by a factor of 30. Not 30%. 3000%. That is, Houston could build freeways to every corner of the city 20 layers deep and they would still suffer congestion during peak hours.
Why is that? Roads and freeways are huge, and expensive to build and maintain, but they actually don’t move very many people around. Typically peak capacity is about 1000 vehicles per lane per hour. In most cities, that means 1000 people/lane/hour. This is a laughably small number. All the freeways in LA over the four hour morning peak move perhaps 200,000 people, or ~1% of the overall population of the city. 30x capacity would enable 30% of the population to move around simultaneously.
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Spacing between the bicycles, while underway, is a few meters, compared to 100 m for cars with a 3.7 m lane width. Bicycles and pedestrians take up roughly the same amount of space.
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Like a lot of public infrastructure, the cost comes down to patterns of utilization. For any given service, avoiding congestion means building enough capacity to meet peak demand. But revenue is a function of average demand, which may be 10x lower than the peak. This problem occurs in practically all areas of life that involve moving or transforming things. Roads. Water. Power. Internet. Docks. Railways. Computing. Organizational structures. Publishing. Tourism. Engineering.
This effect is intuitively obvious for roads. Most of the time, the roads in my sleepy suburb of LA are lifeless expanses of steadily crumbling asphalt baking in the sun. The adjacent houses command property prices as high as $750/sqft, and yet every house has half a basketball court’s worth of nothing just sitting there next to it. Come peak hour, the road is now choked with cars all trying to get home, because even half a basketball court per house isn’t enough to fit all the cars that want to move there at that moment. And of an evening, onstreet parking is typically overwhelmed because now every car, which spends >95% of its life empty and unused, now needs 200 sqft of kerb to hang out. Most of the time, the road is far too big, and the rest of the time, it’s far too small.
People often underestimate the cost of having resources around that they aren’t currently using. And since our culture expects roads and parking to be both limitless, available, and free, we can’t rely on market mechanisms to correctly price and trade the cost. Seattle counted how many parking spaces were in the city and came up with 1.6 million. That’s more than five per household! Obviously most of them are vacant most of the time, just sitting there consuming space, and yet there will never be enough when they are needed!