Comment by cyberax | Hacker News Reader

Comment by cyberax | Hacker News Reader

Parent Full thread

An average bus load in the US is around 18 people. So if you just compute the raw bus emissions, then an electric bus is maybe about 2x more efficient than personal EVs.

But wait, there's so much more!

A single bus/subway ride costs about $20, which is a surprisingly consistent figure for various US cities. In NYC it's $17, for example. I'm talking about the _true_ cost, as in: "yearly operational budget divided by the number of trips". And most of this cost comes from 3-4 drivers that every bus needs, not from the hardware itself.

Price is a pretty reliable proxy for CO2 emissions for general market goods and services. And with these kinds of numbers, personal cars are competitive. Even if we factor in subsidized road maintenance cost ( https://taxfoundation.org/data/all/state/state-infrastructur... ).

If we now add mild carpooling, so that a single robotaxi drives 2-3 people, then classic transit just dies. It's like comparing horse-drawn carriages with steam trains.

Most of the cost comes from paying the drivers, but also cost is a proxy for emmissions?

Yes? Why is this strange?

Drivers emit a lot of CO2, just like every person in the US. A driverless car allows these emissions to be reallocated to other more productive areas.

You're counting emissions from a person's breathing as part of the vehicle's emissions?

People take their salaries and buy food, clothes, heating and air conditioning, cars and fuel, and plane tickets, and furniture. All of those things generate emissions in their production and/or transportation. This is why dollars is such a good proxy for co2 emissions.

Surely a person driving 18 people will emit less than each person driving themselves? I can see how dollars can be a proxy for macroeconomic stuff, for example by comparing countries, but it doesn't make much sense for comparing individual units of transport.

I don't understand why we have to do napkin maths to guess what's more polluting. There is countless research showing buses emit less than individual cars per passenger per km, self-driving or not.

And there's no reason buses can't be self-driving as well, if anything, them driving slower, on dedicated lanes and on fixed routes would make it much easier.

> Surely a person driving 18 people will emit less than each person driving themselves?

No. A person driving themselves does not create any _incremental_ CO2 emissions. They don't need a dedicated full-time position to do the driving.

> There is countless research showing buses emit less than individual cars per passenger per km, self-driving or not.

Care to share it? I actually read through most of highly cited articles in this area, and it's not at all so clear-cut. For example: https://ourworldindata.org/travel-carbon-footprint

The very source you are providing is pretty clear to me. For cars, only hybrids and EVs are more efficient, and that is because it's comparing electric passenger cars with all buses (most of which still run on fossil fuels). There is no data for electric buses, but it's pretty intuitive to me that they would emit less per passenger kilometre than an electric car.

A single bus journey is $20? That's insanely expensive.

Reply on news.ycombinator.com