The NYT’s Seen A “Future Without Cars” But What About 21st Century Cars?


Last week the NYT ran an piece on imagining Manhattan as a "city without cars." Definitely it would be more pleasant, but people also very much want personal transportation, and so closing or narrowing all the streets may not present a great solution and not beyond New York in any event. The problem is that planners still think about 20th century cars, with all their problems and downsides and without the new abilities the 21st century offers for traffic management using smartphones, self-driving and more.

I explore where we can really go in a city with the 21st century car in The future without cars changes with 21st century cars


'unlimited capacity of the sky'. Not so fast, Brad! I thought you were a pilot. Various features really do limit the capacity, and it needs a whole control infrastructure.

And lots of companies, and NASA and the FAA are working on that control infrastructure.

However, I actually don't favour "infrastructure." I prefer vehicles with natural ability to fly in lanes and avoid other aircraft at close distances (compared to flying today.) These are vehicles that can stop and make sharp right turns if you want them to (it's not very efficient but you can do it.)

My approach would be that you would ask for a flight plan, and you would be handed one that intersects nobody else's plan. You would fly that. If you had to divert, there would be emergency escape plans for every point along the plan. Minimal communications would be used after, but you would of course still observe and avoid other vehicles near you.

Is the problem really road capacity? More often it seems the bottleneck is intersections. Even on the interstate, unless it's caused by a crash, the root problem usually comes down to an intersection somewhere.

The capacity is not just of the road but the road network (including intersections) to move the people who need to move into, out of, or through that network.

There's a lot of work in traffic signal control to improve the throughput of intersections, but of course that slows the cross direction so it's not trivial.

However, whatever the capacity is, that's how many cars you let go through that section.

The laws of physics limit the number of cars going through a section to the capacity of that section.

Inefficient use of that capacity is caused by human drivers (and the inefficient traffic control devices, like traffic signals, they require).

Typical capacities are measured in vehicles per hour, and are roughly 1 ever 2 seconds on a highway lane. Physics would allow more if everybody had radio synchronization. So the reality is the capacity is more about human capability (and error.)

Capacity is more about human capability today.

In a 100% autonomous vehicle future, it won't be.

But 100% autonomous is very far away and we want solutions decades before that.

It's not going to take decades before we could have sections of our road network dedicated to autonomous vehicles.

It'll happen much sooner than every car will be equipped with centrally planned navigation instructions that every driver follows like a robot (which hopefully will happen never).

Collectivism is the cause of the traffic jams, not the solution to them.

Well, having every driver follow navigation instructions like a robot is already well on its way. OK, not like a robot, as we make variations, but largely we drive as our nav tells us these days, only making exceptions rarely.

I have no problem with collectivism here. I don't think the roads make sense as a commons. I think they should be a product (publicly or privately owned) and we should be customers, with the rights of customers. Which is to say we go on them only if we've paid, or are otherwise allocated a slot on them. There are only so many slots on an efficiently flowing road. Handing out more slots (or just giving them to anybody who enters) is silly.

I suppose some people follow their nav fairly closely. I doubt it's most. And our nav is generally giving us directions that are in our best interest, not asking us to do things for the sake of the collective according to some central planner. (Personally I rarely use navigation, and when I do use it I often rely on the ability to override its suggestions and let it recalculate my route accordingly. But I'm sure many others, though maybe not most, use it nearly all the time.)

As for your second paragraph, I'm not sure if you made a typo somewhere or I just don't understand it. Public ownership of roads is silly. Most roads should be privately owned just like the Internet is mostly privately owned. Whether or not it should be pay-per-use, or more of a peering arrangement between owners, I think depends on the road, but I think private competition will cause the best allocation.

Lack of good peering is one of the biggest problems. You can build a 10 lane superhighway that handles all the traffic you can imagine, but if your offramps lead to congested local roadways, it isn't going to solve the problem. So I think pay-per-use has some severe limitations.

A business-owner would never put up with such lack of efficiency. They'd force the local roadway owners causing the traffic jams to clean up their act or they'd stop peering with them altogether (unless government forced them to be inefficient with some "network neutrality" rules or something).

Keep in mind that there's no "the government" that owns the roads. Just in the USA there are many state governments, numerous local governments, many private entities, and the federal government, all owning different roads that interconnect and depend on each other. Any collectivist solution would have to take in the competing and contradicting goals of all of them.

The nav will still be acting in your interest, in that if you don't have the right to drive a segment of road, and would get a ticket if did so, your nav wil not steer you there. Indeed it will warn you if you try to drive there. Within the roads you have bought/received accessed to, it will find the best route for you.

For better or worse, roads are publicly owned. That does not mean the government should not run them rationally like a private road. The one advantage of the government ownership is that it can try to fix the peering problem you list. It works best if you can optimize the entire network, but it is possible as you say to optimize networks that consist of cooperating private spaces. Even with government roads, the roads of one city will join with those of another city, or the national or state or county owned roads.

That’s not going to happen. Fortunately.

Which was my original comment. Then you tried to suggest that it was “already well on its way.“

Maybe these kinds of ideas would work some places. Not in the USA. We value our freedom far too much to go for that kind of stuff.


By the way, most roads are not owned by governments in the traditional sense. A right of way is essentially owned by no one, at least so long as it remains a right of way. When a subdivision is platted, the owner dedicates certain areas as rights of way, for the benefit of the homeowners (and because by law any parcel of land must have access to a right of way). No government ever paid for the land under most roads. Charging tolls (or requiring limited reservations) for using those roads without compensating the residents and businesses of that subdivision would likely constitute an unconstitutional taking. And exempting residents/business-owners wouldn't be enough. You'd have to also exempt any guests/customers/employees/vendors/etc. Maybe if you just wanted to restrict/charge through-traffic, you could get away with it. And actually, the residents and businesses living there would love that. But it'd be very difficult to enforce. And any proceeds should go to the people who live there, in which case it's basically private ownership.

Limited access roads, such as interstates, are the biggest exception. They are bought by governments, usually through eminent domain. Governments generally pay the owners for the land they confiscate to build interstates. I would venture a guess that the land under all toll roads was paid for, unlike the land under most roads in general, which wasn't.

Well, whether roads are rights of way or not, the governments claim and get the power to control how people use them. And yes, this would largely relate to through traffic.

So you feel that if you have a road that can handle 2,000 cars per hour before failing into congestion collapse and ruining everybody's utility in it, the right solution to that problem is to just let all 3,000 cars try to use it? Who wins from that? I think the real question is how to decide which 2,000 cars can use it.

Governments claim and get the power to control how people use everything, so long as those claims and controls are constitutional.

Restricting roads to require limited reservations, without compensating the owners of the land under those roads for that regulatory taking, would likely be unconstitutional. So if governments wanted to go with that plan, they'd be well advised to do it through eminent domain, just like how toll roads are currently built.

Fortunately, there's about zero chance of this happening in the USA, outside of the sorts of limited-access roadways that already exist. (Unless we figure out how to tunnel much more cheaply, but in that case private ownership would be the obvious way to go.)

Regarding your second paragraph, I don't think you're capturing the intricacies of what causes traffic jams.

When you say "congestion collapse," do you mean that literally? I haven't ever heard that term being used for road networks, and I don't think it applies. There's no risk of dropping packets, so it's not really a good analogy, if it was meant to be an analogy.

When you say a road "can handle 2,000 cars per hour before failing into congestion collapse," are you thinking of an interstate that can handle that amount of traffic if all traffic is following the speed limit? Metering is a simple solution to that problem, and even that isn't necessary once you have autonomous vehicles that can self-meter and coordinate a perfect zipper merge at high speed (and autonomous vehicles will be able to go higher speeds, thereby increasing the throughput of the same roads in terms of cars per hour). Of course, with metering you get backups in the places before the meter, but as long as you have a big enough waiting area so that the waiting traffic isn't blocking intersections, the problem fixes itself.

For sure there is a use for my navigation system to recognize that there are 1,000 cars in the waiting area to get onto I-95, and give me a different route or if that's not possible tell me of the increased delays so I can choose whether or not to just stay home. Even without a navigation system, it will become clear that certain areas have long queues at certain times of the day, and people will adjust accordingly. Waiting sucks, but it's the price of socialized road networks.

For interstates, rather than some complicated and collectivist system where everyone tells their driving plans to Big Brother and Big Brother decides who gets delayed and who gets places on time, I think it's enough to combine metering with much much much more capacity for on-ramp and off-ramp queueing. Especially off-ramp queueing. The on-ramp queueing can be fixed over time by adding more lanes. Fixing the off-ramp queueing requires coordination with local governments, who may be unwilling to help with something that's "not their problem." Maybe leverage can be used, though ("if you don't fix your local traffic problems, we're going to remove your off-ramp"). Also, some local traffic problems are caused by events. In that case it makes sense to get the entity hosting the event to pay to fix the traffic problems. Again, threatening to close the exit ramp if they're unwilling to help could be used.

You're right that you can't send 3,000 cars per hour on a road that can only handle 2,000 cars per hour. But the problem is when there are only 200 cars per hour using that road, due to merging delays (fixed by metering) or exit ramp delays (fixed by having adequate queueing space).

For local roads, I prefer a free market approach, but absent that this is largely an issue for local zoning boards. Some are good at making sure that the owner of land that is rezoned from farmland to support a 100,000 employee office complex pays for the infrastructure improvements necessary to support that. Others don't.

I don't think there's any need for a Big Brother approach to any of this.

I think the real question is how to decide which 2,000 cars can use it.

My preferred answer to that question would be to let the free market decide that.

And by that I most certainly do not mean that the government should simulate some half-assed plan that vaguely resembles the free market.

But mostly, I think the question is flawed.

I am talking about metering, but of road networks, not just on-ramps. How are cities like New York able to implement congestion charges if they don't own the roads? Of traffic lights for that matter?

Tolls and a market would be a good answer but politically they don't fly in many places, even the USA. Even congestion charging has been resisted in the USA until very recently.

By congestion collapse I refer to the famous backwards-C speed-flow curve. As you try to push flow too high, you get the collapse of a traffic jam. There isn't one magic speed, but the more cars try to use the road, the more likely the jam is. And that is indeed what metering lights are for.

But if you can put a charge on entering a road network, I don't see why it would become a takings if you meter it in some other way. One approach used in several countries is to allow even licence plate cars on even days and odd plates on odd days. That hasn't been done in the USA, but woould it be a takings. While that system is easily gotten around by the rich (get 2 cars for commuting) its core idea is valuable.

You're calling it big brother, but are they big brother when they set traffic rules? When they make carpool rules? When they set streets one way are they controlling your life by refusing to let you go the other way?

It's in everybody's interests that you don't put so many cars down a road that it collapses into a traffic jam. If one operates a private road, you are going to want to prevent those jams and your customers are going to want it too.

How is government allowed to require people to wear masks in stores if they don't own the stores? The government's power to make laws in order to keep people safe is not limited to land that they own.

By congestion collapse I refer to the famous backwards-C speed-flow curve.

I can see how that applies to limited access roads, where metering works well to prevent it. But how does that apply to local roads, where the bottlenecks are at the intersections?

Do you have any success stories you can point to? I'm open to the idea of whole road network metering, if it can be implemented in a non-draconian and non-Big-Brotherish way. But I'm not sure how you'd do that without privatizing roads.

But if you can put a charge on entering a road network

Metering is not a charge. It's basically just a traffic light. In fact, it often is literally a traffic light.

Furthermore, as I believe I said above, governments generally do own the land under the interstates and other limited access roads. I say generally, but I'm not aware of a counterexample.

The NYC congestion surcharge is just a tax on certain businesses. It's little different from the taxes on taxicabs that have existed for decades. As far as I can tell, it only applies to taxicabs, limousine services, and similar businesses (including Uber et. al.).

You're calling it big brother, but are they big brother when they set traffic rules?

No. Not normal, sane traffic rules, anyway.

A device that I need to carry with me whenever I travel, that sends my intended travel plan to the government, and tells me whether or not I'm allowed to travel, and when, and what route to take. That's Big Brother.

When they set streets one way are they controlling your life by refusing to let you go the other way?

I dunno. That's an interesting question. I'm not sure how it's relevant, though.

It's in everybody's interests that you don't put so many cars down a road that it collapses into a traffic jam.

I don't know about everyone, but I don't have a problem with preventing so many cars from going down a road that it collapses into a traffic jam.

What you were suggesting was way way more than that.

What I was suggesting is exactly that. That to stop more cars going into a road than it has capacity to handle, you hand out slots to be one of those cars. You might sell them, you might allocate them by lottery, you might ration them. That's a traffic light -- you have a slot, you can go. You don't have a slot, find another way.

Why you would follow your navigation system like a robot? Because it is almost surely the tool by which you would arrange to get slots to drive the routes you want to drive, and which know what slots you had, and direct you on the best way to use them. If you don't, you might cross somewhere you haven't got a reservation for, and pay the fee to do that, which might be quite high.

"Exactly that" may be your goal. I don't think your proposed means of achieving that goal are acceptable.

Traffic lights aren't great. I'd like to see many if not most of them replaced with roundabouts or some other less dictatorial traffic control device. But traffic lights are not nearly as draconian, dictatorial, and Big-Brotherish as what you're proposing, which seems to be the equivalent of requiring drivers to file an IFR flight plan in order to drive to work.

I can respect your opinion that you'd like more governmental control over people's everyday vehicular travel, but it's hard for me to respect your denial that your proposal involves substantially increased government surveillance and control. And I can't help but noticing how this increased government surveillance and control would facilitate achieving your desire to shut down normal daily activities (which has caused unprecedented unemployment levels). You want to drive to work today? Sorry, request denied. Your livelihood has been deemed by the Ministry of Calm to be non-essential.

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