[cyberax]

> Self-driving cars still take up space on the road

This is a false argument. Think about this: a bus every 10 minutes is effectively 500-900 meters long! It easily "takes" as much space as 100+ cars. In other words, nothing would change from the traffic perspective if instead of 1 bus every 5 minutes, you had 100 individual cars.

The "people in the shape of a bus" argument makes sense only when you're talking about the performance in a very narrow case of transporting people in a steady, uninterrupted stream of buses. Or if you need to size your traffic bottlenecks.

Moreover, a bus route necessarily is unoptimal for at least some people on a bus. They are effectively "thicker" than other people because they take up more "effective space". But wait, there's more! Buses also necessarily move slower due to stops, so the "effective length" of a bus becomes even longer because cars will clear the road faster.

But wait, there's even more! A single bus needs about 3 drivers to be effective. So with the average daily busload of around 15 people, you have almost 20% of the bus taken by the drivers on average. This makes bus trips pretty expensive. Not quite to the level of Uber/Lyft, but surprisingly close.

And these problems are fundamental. That's why urbanists like NJB don't like to talk about that.

[mcv]

Nothing about this addresses NJB's argument that self-driving cars take up more space than regular cars, because there will now be cars with 0 people in them.

Ultimately the thing you want to transport is not cars, it's people. Walking fits the most people in a limited amount of space, then bikes, buses and other forms of public transport, then cars with 4 people in them, then cars with 3 people in them, then cars with 2 people in them, then cars with only 1 person in them, and finally empty cars. More cars will never reduce congestion.

But to address your point: A bus in a dedicated lane takes up more space than a bus that's stuck in car traffic, you are right about that. On the other hand, when congestion is so bad that cars simply don't move, no matter how many lanes they have, getting people out of cars into more efficient forms of transport, will also help cars. And a bus that actually goes, can do that. If you look in cities with good public transport, more people go by public transport than by car. In cities with good bicycle infrastructure, more people go by bike than by car. That means even cars are less likely to get stuck in traffic in those cities. Even if you take away a car lane.

I don't know where you got the idea that a bus needs 3 drivers.

[cyberax]

> Nothing about this addresses NJB's argument that self-driving cars take up more space than regular cars, because there will now be cars with 0 people in them.

And? There are also buses that trundle around with nobody but the driver in it. Or unused bikes and e-scooters that litter the sidewalks.

> Ultimately the thing you want to transport is not cars, it's people.

Yeah. And let's make it efficient. Put these people into 3-level bunk beds. This way they can travel all together in just 1 bus to their assigned workplace. And you don't need to run buses until they're allowed to clock off their shift.

Efficiency!

> On the other hand, when congestion is so bad that cars simply don't move

In this case you close the downtown offices and force them to work on alternate days, like they do in India with cars. Remote work already can replace 70% of all work, and with AI this number will grow.

Apart from that, mild carpooling will decrease the number of cars by 2x. Small vans with 6 seats can _easily_ remove all congestion.

> no matter how many lanes they have, getting people out of cars into more efficient forms of transport, will also help cars.

Just one ask for urbanists. Can you just stop lying, please? Just one thing. Don't say that "transit help cars". It doesn't. There is a lot of research from _you_ (e.g. https://archive.strongtowns.org/journal/2020/1/7/does-buildi... ) that proves this. Transit does NOT decrease the travel time for cars ("traffic") it _increases_ it by increasing congestion due to increased housing density that transit forces.

You want to pack people into 3x3 jails ("microapartments")? Fine. But be honest about it.

[yunwal]

> a bus every 10 minutes is effectively 500-900 meters long!

uhhhhhh what. What does every 10 minutes have to do with this at all

> It easily "takes" as much space as 100+ cars.

are you ok??? have you seen a bus before??

> A single bus needs about 3 drivers to be effective

I have never ever seen a bus with 3 drivers in it. If you're talking about 3 drivers over the course of 24h, those drivers are not in the bus at the same time, and therefore don't make up 20% of the passengers on the bus. If you're saying the average bus route serves 15 people per day, you are certainly mistaken.

[zimpenfish]

> If you're saying the average bus route serves 15 people per day, you are certainly mistaken.

Definitely mistaken for London - currently (according to DFT's numbers) about 18 people per bus average (not per day, though.)

[cyberax]

> uhhhhhh what. What does every 10 minutes have to do with this at all

See the word "effective". Think about the road space that a bus requires but doesn't use if it is just once per 10 minutes.

> I have never ever seen a bus with 3 drivers in it. If you're talking about 3 drivers over the course of 24h, those drivers are not in the bus at the same time, and therefore don't make up 20% of the passengers on the bus.

Yes, I'm talking about the drivers that are needed for a reasonable 16-hour bus service. And the typical ratio is actually a bit more than 3 drivers per 1 bus.

> If you're saying the average bus route serves 15 people per day, you are certainly mistaken.

No. I'm saying that on _average_ there are 15 people in a bus. More during the rush hour, fewer during the off-hours.

[gbbgbbgbb]

> See the word "effective". Think about the road space that a bus requires but doesn't use if it is just once per 10 minutes.

Excepting the case of a dedicated bus lane, the amount of road space a bus is preventing other cars from taking up at a given time is equal to the size of the bus. Technically, it's less than that in the case of bus stops littered amongst parking. In the case of a dedicated lane, it reduces the maximum throughput of the thoroughfare, but it's not a simple thing to model as there are other effects that the bus can have to reduce the number of cars when the rate limit of thoroughfare would be pertinent (i.e. usually rush hour). Just saying "think about it" when saying a bus takes up the space of 100+ cars doesn't really substantiate such a bold claim.

> Yes, I'm talking about the drivers that are needed for a reasonable 16-hour bus service. And the typical ratio is actually a bit more than 3 drivers per 1 bus.

> No. I'm saying that on _average_ there are 15 people in a bus. More during the rush hour, fewer during the off-hours.

If there is an average of 15 passengers on the bus during the operations of the bus and there is an average of 1 driver on the bus during the operations of the bus, then it is 1/16th occupied by driver(s). For it to be taken 20% by driver occupancy, then it would require there to be an average of 4 passengers on the bus during operations.

[cyberax]

I actually am citing the traffic engineering handbook, the section about computing the efficacy of bus lanes. And I'm using deliberately conservative estimates.

> If there is an average of 15 passengers on the bus during the operations of the bus and there is an average of 1 driver on the bus during the operations of the bus, then it is 1/16th occupied by driver(s)

No. For the bus to be viable, all 3 drivers have to be "virtually present" there. A bus _has_ to be available at all times with a reasonable interval, otherwise it might as well not exist.

Or in other words, a passenger needs to be paying the salary for even the missing drivers.

[gbbgbbgbb]

> I actually am citing

until this moment, you were only claiming.

> the section about computing the efficacy of bus lanes

> Excepting the case of a dedicated bus lane

Not all buses require a bus lane. A bus lane is a deliberate choice that doesn't make sense in all areas and for all bus routes. It is disingenuous to reference the reduction in throughput due to a bus lane as a blanket claim that an individual bus takes away the room of 100+ cars on the road.

> you have almost 20% of the bus taken by the drivers on average

> No. For the bus to be viable, all 3 drivers have to be "virtually present" there.

Your claim is about how much of the bus is taken by drivers, which while having some correlation to cost, really doesn't have anything to do with the cost of operating the bus. An oversimplification of this is to posit a magic bus that runs 24 hours a day with 8 hours shifts by 3 drivers. That means that the drivers take up 24 person-hours of capacity on the bus. If we say they have 15 passengers on average, then the passengers take 360 person-hours of capacity on the bus. Thus, drivers take up 24 / 384 or 6.25% of the capacity.

Honestly, I never really cared enough to convince you that transit is a good thing because that feels like a fool's errand. But these weird claims and fallacies bother me. If you want to claim that a bus isn't cost effective, then great. Just cite an actually relevant metric and actually calculate it correctly.

[yunwal]

So where is the 20% of passengers are drivers thing even coming from?

[cyberax]

3/(3+15) = 3/18 = 1/6 ~= 20%

[yunwal]

Only 1 of those 3 drivers is on the bus, sorry!