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Comment by BenFranklin100 | Hacker News Reader

As an aside, an argument in favor of mass transit vs electric cars, is that EVs do nothing to reduce particulate matter pollution from tires and breaks.

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Unless there's a ramification of electromagnetism that I'm missing, cars that do the bulk of their braking through regeneration require their conventional brakes to absorb far less energy, reducing the particulate matter generated.

However they're much much heavier, generating more tire and brake dust.

And unless the mass transit is tireless, it will be even heavier. Tire wear and this microplastics go up with the square of axle weight, so individual transportation is actually better from that standpoint.

But mass transit carries more people per wheel, and the weight of the bus does not scale linearly with the carrying capacity, so it doesn't automatically follow that "individual transportation is actually better...". I doubt that 50 EVs carrying one person each generate less tyre wear than one bus carrying 50 people.

Road damage is a function of the power of 4[1] generally.

A BYD bus weighs 18 tons and carries 32 people including the driver. [2]

A BYD Atto 3[3] carries upto 5 people and weighs 1.8 tons unloaded.

The proportional road wear function of the BYD Atto would be about 10 (1.8^4). For the bus it would be (18^4) 104,976.

So the bus is 10,000 times more wear then the car. Per passenger it's 3000 wear units for the bus versus ~10 for the car.

[1] https://en.m.wikipedia.org/wiki/Fourth_power_law

[2] https://en.m.wikipedia.org/wiki/BYD_K_series

[3] https://ev-database.org/car/1782/BYD-ATTO-3

Roads are for walking, bicycling and repair/cleaning/utility/emergency services. Deliveries go by subterran pallet-delvicery networks, to be last-miled by freight-cycles. Mass-transit by rails. Long-transit by maglev or air.

Fuck cars!

This only works where the population has a very high average IQ (ability to understand second and third order effects of long expensive projects), no anti-social behavior (no corruption or theft in public works projects), with politicians whose interests align with the people. Unfortunately we live in a world where you will be stabbed to death and robbed for walking down the sidewalk holding a $20 bill openly in your hand.

There are regional differences to that sort of behaviour.

The average car carries 1.2 people, how many does the average bus carry?

The 10 number is for literally one person, I'm also discounting their mass (this isn't a precision exercise).

If you add 5 people to the car, call it 80kg per person so your you goto about 2.2 tons, then the damage number would be about ~24, but divided by 5 you end up with 4.8 (so a fully loaded car does about half the damage per person compared to one with a single occupant).

The thing is of course on some level this is large scaling factors applied to small numbers - i.e. tires still don't fail that quickly anyway, neither do roads.

Conversely it is actually weird to see that on this one metric, numerous self driving EV taxis is actually better.

>Road damage is a function of the power of 4[1] generally.

Per axle. So for instance, if you're comparing an 18-wheeler to a 4-wheel car you have to compare (truck-weight/9)^4 to (car-weight/2)^4. Or ((truck-weight/9)/)car-weight/2))^4

So if a bus was an 18-wheeler, it would be about 16x the wear units, /32 passengers brings it to half.

It doesn't make a difference for the bus you linked, since it's also a 4-wheeler like cars, but if we cared we could add more axles to buses.

But, why don't we do that already? Apparently...

1) regulations don't require it

2) we sort of already do; some buses have rear wheel bogies that have 4 wheels of which 2 are kept raised at lighter weights. Which is basically all the time because regulations don't require it.

3) more wheels reduces fuel efficiency (and costs more money), obviously

4) wheels take up space and reduce passenger capacity, which make the bus less efficient if you don't care about road wear

5) buses have a much more consistent weight load than trucks, since ~30 passengers would be only 3 tonnes of difference.

I'm wildly out of my depth on buses/trucks here, so if a mechanic could chime in on bus/truck weight distribution and wheels that'd be great.

Subways produce a ton of particulate too. Stations are always dusty and transit operators don’t seem to care about investing in better ventilation for the platform.

I did some research and it seems this is already a problem with ICE vehicles because of the pickup/SUV trend.

I don’t know how precise this data is, but apparently the top selling models in the US are [1]:

1. Ford F-150 (1,846–2,584 kg)

2. Chevrolet Silverado (2,029–2,272 kg)

3. Toyota RAV4 (1,530–1,640 kg)

4. Tesla Model Y (1,884–1,998 kg)

5. Honda CR-V (1,500–1,681 kg)

6. Dodge Ram (2,176–3,418 kg)

7. GMC Sierra (2,029–2,272 kg)

8. Toyota Camry (1,480–1,660 kg)

9. Toyota Tacoma (2,007–2,032 kg)

10. Tesla Model 3 (1,611–1,836 kg)

They do seem to average 200-300 kg more than a comparable ICE model but as a whole they’re not tremendous outliers.

[1]: https://www.edmunds.com/most-popular-cars/

Very interesting, thank you for sharing the numbers

ICE vehicles are getting larger because they're exempt from fuel economy requirements.

You can do the same by engine braking with a stick shift, tapping the break only to hold you still at the end if you really wanted to. And the car could be a 2000lb subcompact.

> is that EVs do nothing to reduce particulate matter pollution from tires and breaks

Except for not using brakes for the most part. EV brakes typically last for the life of the car.

https://en.wikipedia.org/wiki/Regenerative_braking

And your tires?

Your quote:

> EVs do nothing to reduce particulate matter pollution from tires and breaks.

"Substantially reduce particulate matter pollution from brakes" sounds like doing "something", not "nothing", to me.

Which is why I used a logical conjunction.

https://www.oecd-ilibrary.org/sites/4a4dc6ca-en/1/3/3/index....

If one thought EVs did something help with one of the two, they'd have omitted it from the list of things "EVs do nothing" to help with.

Something that helps with X cannot be said to do nothing to help with "the problem of X and Y". If they reduce it for tires, then they do reduce the problem of "particulate matter pollution from tires and breaks" - proportionally to how much the latter contributes to said problem.

Um, no.

https://ocw.mit.edu/courses/24-241-logic-i-fall-2009/

Good luck.

And the link to a logic course somehow proves you right for saying "EVs do nothing to reduce particulate matter pollution from tires and breaks"?

Dude, you just pulled the weird-ass argument about "that's why I used a conjuction" in a hail Mary attempt to pretend you already knew about them reducing break pollution.

As if any person who actually knew EVs reduce particulate matter pollution from breaks would ever say: "EVs do nothing to reduce particulate matter pollution from tires and breaks" - implying they meant "they don't reduce BOTH" all along.

Seriously, sign up for the course. You would benefit.

EVs don't do that, regen braking does that. Regen braking can be fitted to hybrid or ICE cars.

Well, you were the one who grouped them. The reality is that EVs wear tires equivalently fast to other similar weight vehicles and wear brakes very very slowly. And reduce carbon emissions. And noise.

I grouped them together,because overall EVs appear to have marginally less non-exhaust particulate matter pollution than gas vehicles:

https://www.oecd-ilibrary.org/sites/4a4dc6ca-en/1/3/3/index....

In other words, the road to a mostly pollution free transit future will be laid with tracks rather than asphalt.

It will be laid by first understanding reality, which includes the enormous road network we have today and the social motivations to expand it. Just bleating about how great it would be if everyone used transit isn’t going to change a damn thing.

EVs are a solid and realistic step towards reducing our worst pollution problems. Widely available car sharing and autonomous vehicles would be a great solution to the last mile and even reducing the problem of so much space being used for parking, while improving the walkability of our cities. Look towards possibilities that can work, instead of clinging to models that can’t address the problems of today.

Don’t be silly. EVs, ride shares, autonomous cars, etc.. are a poor transit solution within dense cities, where a significant if not overwhelming majority of car use occurs. These urban environments are ripe for cost effective, efficient mass transit solutions, such as the BRT system Mexico City recently implemented. They absolutely address the problems of today.

Dense cities are only one type of population center. There are suburbs all over the world, there are diverse forms of low population areas, and there are frontiers. The majority of car use is not in city cores, it is in the medium to low areas all over the world, which is by far the dominant land use pattern by area.

Never in America. We live too spread out, and many cities lack coherent work centers.

Depends on if you are doing a lot of acceleration pulls with that sports package you paid extra for in your tesla.

Maybe if you drive like a grandma and not like I see a lot of people with these 4 second 0-60 cars drive are you avoiding the brakes.

Regenerative braking means that if you drive them right EVs can have factory brake pads at 100k+ miles that look new. https://x.com/niccruzpatane/status/1785043593427640326

This also allows for use of drum brakes, which have rare issues of overheating when used alone but are fine with regen doing most of the work. Those contain the abrasion materials within themselves.

Some EVs already use them but to become common it'll probably require new regulations like the EU is planning to overcome the "ugh factor" because they used to be the cheap, low end options.

Thanks to regenerative braking, my brake disks rust long before they wear out. Tire particulates are an engineering problem that will be solved long before the social problem of convincing people to live close enough to make public transit practical.

And your tires?

I'm never going to take public transit in the United States if I can help it because there are too many unhinged psycopaths and it takes just one. When I visit Europe it's all I take day in day out. Except certain parts of Paris and the UK which have had lots of recent arrivals. But even the new arrivals are less insane than many of the characters found on US public transit.

As opposed to in traffic? Plenty of road raging psychos out driving cars.

The conclusion is that the US just has more psychos. But the restraint of wrecking their vehicle to accost me holds them in line. On public transit they can accost me and nothing stops them.

Here in Austin people shoot at eachother on the highway all of the time, there's no need for them to wreck their car

Let's be real for a minute; the relative incidence rate of highway shootings is far lower than the relative incidence rate of violent crime on public transit in American cities.

My not-sufficiently-informed opinion is in agreement with yours. Do you have any studies that we can use to compare shootings versus violent crime rate on public transit?

A quick Google search revealed some data collected by the US government on the topic.

https://www.bts.gov/content/reports-violent-crime-property-c...

You have to be a hermit in a cave if you want to actually do that. Those same people you worry about are also in the grocery store, in the parking lot, at the airport, on the sidewalk, walking around your property. Really there is no added risk in taking transit because you’ve already taken on the risk anywhere else public facing. If anything there’s less risk on transit than many other places you’d find bad characters considering there are surveillance cameras, witnesses, and a driver whose job it is to call the police.

Nope, I lived in downtowns for ten years: Houston, Miami, Denver, and New York City. I've had enough.

Violence and "crazy" people tend to be clustered in certain areas and not spread generally among the populace. For example, I bought a house in a "genteel" part of a mill town. In other words, the houses are maintained. 2 miles away in the "mill worker" section of town (not very well maintained housing) we've had numerous reports of violence, and one or two murders.

I can go to my local supermarket, Home Depot, drugstore, ice cream stand and never encounter any violence. Travel on the bus however and well, the police reports say it's a different story. With the reality? Not sure but every time of been on public transit, it's a cluster of "crazies" mixed in with the general populace.

What this tells me is the problem is not public transit or urban spaces. We need to build a more humane city like what they have in Scandinavia (high public trust, services to keep you from being desperate, respect for common individual property) and the risk of violence will drop both in city spaces and on public transit.

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