[quantumwannabe]

Be careful what you wish for.

Under a fair weight tax scheme, a passenger of a fully loaded bus would pay more than a solo driver of a Hummer EV (one of the heaviest SUVs on the market).

Some data on bus weights [1]:

      Transit Bus Type           Passengers         Curb Weight (lb)   Fully‐Loaded Weight (lb)
                            Max Seated Max Total 
  2‐axle 35‐foot               27 – 40   46 – 72     15,450 – 28,510       23,360 – 39,020
  2‐axle 40‐foot               35 – 44   61 – 92     20,520 – 32,520       30,600 – 44,100
  2‐axle 45‐foot               44 – 46   80 – 86     30,130 – 30,450       41,480 – 42,530
  3‐axle 45‐foot Double‐deck   79 – 82   116 – 122   36,560 – 37,930       54,670 – 55,850
  3‐axle 60‐foot Articulated   41 – 61   89 – 123    37,920 – 49,520       55,975 – 64,690

The Hummer EV's curb weight is 9063 lbs (add 150 lbs for an average driver) and it has two axles for a loaded axle weight of 4607 lbs.

A three axle articulated bus with 123 passengers has a loaded axle weight of 21,563 lbs using the data from the table above.

This means that the bus has ~4.7 times the load per axle as the SUV, so per the fourth power law, it does 488 times as much damage to the road as the SUV. Since it carries 123 people, that means that each bus passenger is doing ~4 times as much damage to the road as the SUV driver.

[1] https://onlinepubs.trb.org/onlinepubs/tcrp/docs/TCRPJ-11Task... (Table 7/Page 25)

[eesmith]

I think that rather than use this source as a way to highlight issues with a strict interpretation of the 4th-power law, you should have commented how your source says you should not use a strict interpretation of the 4th-power law.

For example, it highlights how the damage also depends on the road construction, with highways and major arterials built to a higher standard.

As a general rule, a fully-loaded 123 passenger bus is running on an arterial, not a residential street like someone driving their Hummer EV home does, so you can't compare the road damage simply by axle weight.

Your source even highlights how "it is possible for fewer, heavier buses to damage pavement less than more, lighter buses."

That's all part of larger cost/benefit analysis, like how building for a longer service life for the bus means using heavier parts, which increases the weight, or how running fewer, larger buses reduces emissions per passenger-mile.

The owner of the Hummer EV does a different cost/benefit analysis, with some of the costs born by the government and thus shared across the taxpayers. Without extra fees for heavier vehicle owners, they end up paying the same as light vehicle owners despite the higher negative impacts of their heavy vehicles.

[scythe]

This is not apples-to-apples, because buses don't drive on all of the roads, whereas cars drive on (presumably) any road. The total mileage of roads used for bus routes is a small fraction of all road mileage, even where bus systems are extensive. So more roads must be maintained for cars. Road damage is also affected by vehicle speed, acceleration, braking and so forth; buses drive regular routes at regulated speeds and do not brake very hard.

[avianlyric]

Does all that take into consideration the number of tires per axel, and size of the contact patch for each axel?

I would assume that road damage is proportional to surface pressure at the contact patch, so greater contact patch means less damage. As a result you can have a heavier vehicle do less damage than a lighter vehicle with the same number of axels, if the number and size of tires on the larger vehicle is greater than the smaller vehicle.

Most busses I see around run large truck tires, and normally have 4 tires on the rear axel vs the normal 2 you’ll find on a Hummer. So a bus spreads it weight over 6 tires rather than 4, and if we generously assume the Hummer tires and bus tires have the same contact patch, that means a bus can be 50% heavier than the Hummer, but not cause any additional damage.

I know loading regulations are normally done based on axel number, rather than tire number. But I assume that’s mostly down to ease of regulation, rather than axel count being the most accurate way to calculate road damage. Indeed the document you link too even breaks down loading limits based on number of axels, but also single tire limits, which maybe different depending on pressure of the tire.

Edit: I also note that U.S. buses seem to be much heavier than necessary. As a point of comparison a two axel double decker, New Routemaster in London[1], which carries up to 87 people, has a curb weight of only 28,000lbs, which would give it a fully laden weight of only 29,000lbs. That’s substantially less than equivalent buses in that document.

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

[anigbrowl]

Now consider how many hummers you'd need to transport 123 people.

[alamortsubite]

Ironically, they did open by writing, "Be careful what you wish for."

[ponector]

It is easy to exclude vehicles used for mass transit. Let's say every vehicle which required a driver license D is exempt of such tax.

I generally agree, personal vehicles should be taxed based on weight and power. Small taxes for small cars(fiat 500) and extra high taxes for ridiculously heavy and/or powerful vehicles like 911 or cybertuck.

[JumpCrisscross]

The point is you’d have to create an exception. The rule doesn’t work naturally, which implies it might be flawed.

[ponector]

You think any rule should have a one flat rate. One size fits all?

To be fair, rule should have different multipliers. Small rate for small car and buses, huge rate for trucks. Easy.

[JumpCrisscross]

> You think any rule should have a one flat rate. One size fits all?

No, but it's more elegant and less gameable that way. Otherwise, we wind up with the Section 179 problem [1].

[1] https://over6000pounds.com/electric-vehicles-that-unlock-the...

[9dev]

I don’t understand why we can’t have this, and exemptions for public transit, or human transportation companies providing municipal services?

Don’t let perfect be the enemy of good. If a solution isn’t as elegant as possible, but significantly reduces the amount of SUVs on the roads, it’s a good thing - period.

[outside1234]

The tax would be divided by occupancy