UPDATE 2023: I’ve learned one more thing about the road damage formula. It’s not just axle weight to the 4th power, you must then multiply that by number of axles. Since most bikes and cars have 2 axles most of the numbers in this post stay correct, but a 5 axle big rig will actually do 2.5x more damage than calculated below. Adding more axlese still reduces damage by better distributing weight and lowering the number being raised to the 4th power, but it isn’t magic.
Incredibly janky port of comments from my old WordPress site:
Andrew
2021-03-25 at 11:07 pm
Another great article and captures the bulk of the issue. A few caveats worth mentioning from this traffic engineer:
– This all accelerates an order of magnitude where studded tires are allowed and the tire fees don’t come close to covering it.
-Road damage isn’t the only direct cost. The needed right of way, pavement, signals, etc needed to supply capacity in the form of new lanes (including bike lanes and sidewalks) is another factor. For vehicles, this points to a GPS tax structure that charges more at peak times. Less peak demand = smaller roads needed.
– Fundamental to this all is a transportation funding structure that makes new highways cheap, but does little for those outside a car, safety, etc. and creates unsustainable maintenance obligations at the state and local level.
– To venture into politics, this is one area where the “pay your own way/personal responsibility ” party is willfully blind to the massive suburban SUV subsidy.
Glad you enjoyed the post, and very gratified to hear that an actual traffic engineer is on board with this idea. You make a good point about the costs of signals, etc. My “It’s fair to pass the initial construction costs of a road to all users” sentence tried to address this, but I admit I glossed it over a bit as the article was already feeling too long. I’d be fine with those initial construction costs coming from general tax funds (which in reality they already pretty much are) because it’s very hard to identify exactly who will use a road/sidewalk/bike path before its built, and even those who don’t use it may benefit by reduced congestion on the roads/sidewalks/bike paths that they do use. My main goal is for the big maintenance costs to be paid by the vehicles that we know are causing the damage to them, and for this fee to help push people to use lighter vehicles which will cause less damage and thus be cheaper. Till we do something about this vehicles will just keep getting heavier because the costs of road destruction from heavy vehicles are mostly passed along to everyone else.
I agree with your basic politics point as well. For me it’s pretty obvious that Rs have not been the actual party of fiscal responsibility for a long time now. Ds still have work to do on this, but they’ve done a better job at actually looking at economics rationally the past few decades than Rs have. I hope that sensible people can push Ds to improve even further on this matter. It’d be nice if Rs came back to reality on this too, but as the power base of that party descends further into fantasy land on a myriad of issues I’m losing hope that’ll happen.
Incredibly janky port of comments from my old WordPress site:
Ray
2021-03-08 at 9:31 am
Using GPS to help calculate a tax based on a miles x vehicle weight formula could be a means to charge for the actual damages that drivers incur on roads, but difficult to legislate. People resist whatever they perceive to be an invasion of privacy. This proposal would make all streets and highways effectively become toll roads. Some of the assumptions from the study might be challenged as well. For example, two vehicles of the same weight could impact road wear differently if they have different types of tires/wheels/suspension, or by their driving speed/style. Other variables affecting road wear include the construction method in preparing road beds, soil integrity, materials used, slope, weather, climate, etc. The research on highway damage upon which you base your argument is nearly 70 years old. Maybe nothing has changed in 70 years, but it seems like there might be additional data. Should stop and go drivers be taxed at the same rate per weight x mile as highway drivers? Should a trucker driving on gravel roads in the arctic be taxed at the same rate of weight x miles as one driving on an interstate highway in the south? Should bicyclists and pedestrians pay a road tax too? A bus carrying thirty people might cause as much road damage as thirty people each driving in separate vehicles, but I suspect that the total environmental impact of the bus would be less than that of 30 separate cars. There will need to be some new mechanism to fund roads that is not based so much on fuel, and preferably tied to actual road use. It might also be possible to regulate and tax tires and wheels more. I recall discussions of this issue from decades ago. The GPS technology enables the old idea of toll roads to work more efficiently and less visibly. It’s worked pretty well for Hot Lanes, although there could be lots of exceptions and variabilities in payment methods, as well as potential for fraud and abuse if made into a funding system that affects everyone who uses a road.
Good point on GPS tracking of miles driven as being politically difficult. That’s why I’d only recommend it for commercial vehicles, and even there I’d be okay if they just used the current IFTA reporting process which allows both GPS and manual recounting of where a truck travelled. Even with that, I think you’re right that this will still be a challenge to pass. Michael Webber wrote an Op Ed on the need for an even simpler miles*weight fee back in 2013 and obviously that hasn’t happened yet (https://www.nytimes.com/2013/12/24/opinion/how-to-overhaul-the-gas-tax.html). The added complexity of weight*weight*weight*weight*miles will be even harder to pass with a populace that isn’t super into doing math. That doesn’t mean we should leave it out of the conversation though as it truly captures the damage that vehicles do to roads.
In terms of updated research, there hasn’t been that much need. Unlike a lot of things road building tech hasn’t changed all that much in the last 70+ years. There is some debate over whether total vehicle weight matters more than axle weight, and you can read my heavy vehicles do far more damage to roads than light ones link for more info on that (total weight certainly is more important for durability of bridges). https://www.freep.com/story/news/local/michigan/2019/04/19/heavy-truck-damage-michigan-roads/3474156002/
As for your other Qs, I’ll lay out some quick answers to each.
Should stop and go drivers be taxed at the same rate per weight x mile as highway drivers?
Yes, but it’s a mileage based fee, so a slower moving car will pay a lower fee per hour
Should a trucker driving on gravel roads in the arctic be taxed at the same rate
Yes, the total amount of these fees should be calculated to match to total amount of highway spending. State highway planners can decide what road materials make the most sense for them. Each state could match their fee to their own state spending, similar to how gas taxes differ per state, but actually covering the full costs of roads in the state.
Should bicyclists and pedestrians pay a road tax too?
No, but under the current system cyclists and pedestrians are already paying for roads. The subsidies that go to roads are far greater than gas tax revenues per person in most states. In this proposal these groups would no longer pay many road subsidies, but they wouldn’t all go away. Indirect subsidies like environmental damage from road dust, and direct ones like eminent domain taking land at below market rates would still affect non-drivers. As you can see from the chart at the top, even a fat man on a freakishly heavy bicycle does next to no damage to a road, and funding for the local roads and bike paths non-drivers use already comes from local sources that aren’t the gas tax.
A bus carrying thirty people might cause as much road damage as thirty people each driving in separate vehicles, but I suspect that the total environmental impact of the bus would be less than that of 30 separate cars.
This is true, because road damage is based on vehicle weight to the 4th power a single heavy bus will do more road damage than 30 small cars (similarly 30 small cars will do far more damage than 30 eBikes, or 30 light weight NEVs). At the same time, it will use less fuel than those cars per person mile. I could see exempting buses from the new fee if they travel mostly on local roads which are not currently paid for by gas tax funds. Long distance buses would need to pay the fee though as they are using mostly highways. I could see this as being an issue, particularly for the poor. We could solve it by subsidizing long distance bus travel the same way we subsidize long distance air and train travel.
It’s interesting to do the math on an eBus vs truly efficient EVs/eBikes. The Proterra eBus gets about 25 MPGe, which equates to 74 miles per 100 kWh. Aptera’s light vehicle isn’t out yet, but they claim to be able to get 1,000 miles of range from a 100 kWh battery pack. So 13.5 Apteras (1,000/74 = 13.5) can travel 1 mile for the same energy as 1 eBus traveling 1 mile. Existing electric cars are about 1/3 the efficiency of an Aptera, so they fare even worse.
eBikes on the other hand are kings of efficiency getting 30-85 miles per kWh. Even at the low end of 30 miles per kWh you can power 40 eBikes for the same energy as 1 eBus. At the high end of 85 you could power 115 eBikes with the same energy as 1 eBus. Obviously not everyone can ride eBikes though, but if we’re really trying to optimize or money/energy spending we should be working to enable everyone who would even consider such a mode of transit to give it a try and fill out the remaining transit need with smaller/lighter electric buses.
Road use fees might also point us back to the older practice of trolleys. Riding on tracks would mean that they don’t contribute to road damage at all and thus wouldn’t have to pay the fee. With electric lines running overhead they could also eliminate, or at least minimize battery weight (maybe add a small battery to enable the trolley to handle gaps in overhead electric coverage). I don’t think recent trolley projects have been particularly well done, but I have hopes that they’ll improve more in the future. I also find it interesting that I haven’t heard trolly backers citing reduces wear and tear on roads as another reason to build them. Maybe I haven’t been paying close enough attention, or maybe even they are ignoring this significant cost/savings.
Incredibly janky port of comments from my old WordPress site:
Warren Huska
2022-01-16 at 9:37 pm
Wonderfully done.
The question of bus-equivalence is an interesting one – the road damage on Don Mills in Toronto is notable – raised ‘bus knuckles’.
HOWEVER this does not remove the value of identifying and charging externalities to recoup subsidies.
As I am fond of saying to people who want a ‘road tax’ levied on cyclists, “I can’t wait for my rebate cheque”
Incredibly janky port of comments from my old WordPress site:
Andrew
2021-03-25 at 11:07 pm
Another great article and captures the bulk of the issue. A few caveats worth mentioning from this traffic engineer:
– This all accelerates an order of magnitude where studded tires are allowed and the tire fees don’t come close to covering it.
-Road damage isn’t the only direct cost. The needed right of way, pavement, signals, etc needed to supply capacity in the form of new lanes (including bike lanes and sidewalks) is another factor. For vehicles, this points to a GPS tax structure that charges more at peak times. Less peak demand = smaller roads needed.
– Fundamental to this all is a transportation funding structure that makes new highways cheap, but does little for those outside a car, safety, etc. and creates unsustainable maintenance obligations at the state and local level.
– To venture into politics, this is one area where the “pay your own way/personal responsibility ” party is willfully blind to the massive suburban SUV subsidy.
Profit Greenly (Post author)
2021-03-26 at 10:21 am
Glad you enjoyed the post, and very gratified to hear that an actual traffic engineer is on board with this idea. You make a good point about the costs of signals, etc. My “It’s fair to pass the initial construction costs of a road to all users” sentence tried to address this, but I admit I glossed it over a bit as the article was already feeling too long. I’d be fine with those initial construction costs coming from general tax funds (which in reality they already pretty much are) because it’s very hard to identify exactly who will use a road/sidewalk/bike path before its built, and even those who don’t use it may benefit by reduced congestion on the roads/sidewalks/bike paths that they do use. My main goal is for the big maintenance costs to be paid by the vehicles that we know are causing the damage to them, and for this fee to help push people to use lighter vehicles which will cause less damage and thus be cheaper. Till we do something about this vehicles will just keep getting heavier because the costs of road destruction from heavy vehicles are mostly passed along to everyone else.
I agree with your basic politics point as well. For me it’s pretty obvious that Rs have not been the actual party of fiscal responsibility for a long time now. Ds still have work to do on this, but they’ve done a better job at actually looking at economics rationally the past few decades than Rs have. I hope that sensible people can push Ds to improve even further on this matter. It’d be nice if Rs came back to reality on this too, but as the power base of that party descends further into fantasy land on a myriad of issues I’m losing hope that’ll happen.
Incredibly janky port of comments from my old WordPress site:
Ray
2021-03-08 at 9:31 am
Using GPS to help calculate a tax based on a miles x vehicle weight formula could be a means to charge for the actual damages that drivers incur on roads, but difficult to legislate. People resist whatever they perceive to be an invasion of privacy. This proposal would make all streets and highways effectively become toll roads. Some of the assumptions from the study might be challenged as well. For example, two vehicles of the same weight could impact road wear differently if they have different types of tires/wheels/suspension, or by their driving speed/style. Other variables affecting road wear include the construction method in preparing road beds, soil integrity, materials used, slope, weather, climate, etc. The research on highway damage upon which you base your argument is nearly 70 years old. Maybe nothing has changed in 70 years, but it seems like there might be additional data. Should stop and go drivers be taxed at the same rate per weight x mile as highway drivers? Should a trucker driving on gravel roads in the arctic be taxed at the same rate of weight x miles as one driving on an interstate highway in the south? Should bicyclists and pedestrians pay a road tax too? A bus carrying thirty people might cause as much road damage as thirty people each driving in separate vehicles, but I suspect that the total environmental impact of the bus would be less than that of 30 separate cars. There will need to be some new mechanism to fund roads that is not based so much on fuel, and preferably tied to actual road use. It might also be possible to regulate and tax tires and wheels more. I recall discussions of this issue from decades ago. The GPS technology enables the old idea of toll roads to work more efficiently and less visibly. It’s worked pretty well for Hot Lanes, although there could be lots of exceptions and variabilities in payment methods, as well as potential for fraud and abuse if made into a funding system that affects everyone who uses a road.
Profit Greenly (Post author)
2021-03-08 at 12:24 pm
Good point on GPS tracking of miles driven as being politically difficult. That’s why I’d only recommend it for commercial vehicles, and even there I’d be okay if they just used the current IFTA reporting process which allows both GPS and manual recounting of where a truck travelled. Even with that, I think you’re right that this will still be a challenge to pass. Michael Webber wrote an Op Ed on the need for an even simpler miles*weight fee back in 2013 and obviously that hasn’t happened yet (https://www.nytimes.com/2013/12/24/opinion/how-to-overhaul-the-gas-tax.html). The added complexity of weight*weight*weight*weight*miles will be even harder to pass with a populace that isn’t super into doing math. That doesn’t mean we should leave it out of the conversation though as it truly captures the damage that vehicles do to roads.
In terms of updated research, there hasn’t been that much need. Unlike a lot of things road building tech hasn’t changed all that much in the last 70+ years. There is some debate over whether total vehicle weight matters more than axle weight, and you can read my heavy vehicles do far more damage to roads than light ones link for more info on that (total weight certainly is more important for durability of bridges). https://www.freep.com/story/news/local/michigan/2019/04/19/heavy-truck-damage-michigan-roads/3474156002/
As for your other Qs, I’ll lay out some quick answers to each.
Should stop and go drivers be taxed at the same rate per weight x mile as highway drivers?
Yes, but it’s a mileage based fee, so a slower moving car will pay a lower fee per hour
Should a trucker driving on gravel roads in the arctic be taxed at the same rate
Yes, the total amount of these fees should be calculated to match to total amount of highway spending. State highway planners can decide what road materials make the most sense for them. Each state could match their fee to their own state spending, similar to how gas taxes differ per state, but actually covering the full costs of roads in the state.
Should bicyclists and pedestrians pay a road tax too?
No, but under the current system cyclists and pedestrians are already paying for roads. The subsidies that go to roads are far greater than gas tax revenues per person in most states. In this proposal these groups would no longer pay many road subsidies, but they wouldn’t all go away. Indirect subsidies like environmental damage from road dust, and direct ones like eminent domain taking land at below market rates would still affect non-drivers. As you can see from the chart at the top, even a fat man on a freakishly heavy bicycle does next to no damage to a road, and funding for the local roads and bike paths non-drivers use already comes from local sources that aren’t the gas tax.
A bus carrying thirty people might cause as much road damage as thirty people each driving in separate vehicles, but I suspect that the total environmental impact of the bus would be less than that of 30 separate cars.
This is true, because road damage is based on vehicle weight to the 4th power a single heavy bus will do more road damage than 30 small cars (similarly 30 small cars will do far more damage than 30 eBikes, or 30 light weight NEVs). At the same time, it will use less fuel than those cars per person mile. I could see exempting buses from the new fee if they travel mostly on local roads which are not currently paid for by gas tax funds. Long distance buses would need to pay the fee though as they are using mostly highways. I could see this as being an issue, particularly for the poor. We could solve it by subsidizing long distance bus travel the same way we subsidize long distance air and train travel.
Profit Greenly (Post author)
2021-03-08 at 12:57 pm
It’s interesting to do the math on an eBus vs truly efficient EVs/eBikes. The Proterra eBus gets about 25 MPGe, which equates to 74 miles per 100 kWh. Aptera’s light vehicle isn’t out yet, but they claim to be able to get 1,000 miles of range from a 100 kWh battery pack. So 13.5 Apteras (1,000/74 = 13.5) can travel 1 mile for the same energy as 1 eBus traveling 1 mile. Existing electric cars are about 1/3 the efficiency of an Aptera, so they fare even worse.
eBikes on the other hand are kings of efficiency getting 30-85 miles per kWh. Even at the low end of 30 miles per kWh you can power 40 eBikes for the same energy as 1 eBus. At the high end of 85 you could power 115 eBikes with the same energy as 1 eBus. Obviously not everyone can ride eBikes though, but if we’re really trying to optimize or money/energy spending we should be working to enable everyone who would even consider such a mode of transit to give it a try and fill out the remaining transit need with smaller/lighter electric buses.
Road use fees might also point us back to the older practice of trolleys. Riding on tracks would mean that they don’t contribute to road damage at all and thus wouldn’t have to pay the fee. With electric lines running overhead they could also eliminate, or at least minimize battery weight (maybe add a small battery to enable the trolley to handle gaps in overhead electric coverage). I don’t think recent trolley projects have been particularly well done, but I have hopes that they’ll improve more in the future. I also find it interesting that I haven’t heard trolly backers citing reduces wear and tear on roads as another reason to build them. Maybe I haven’t been paying close enough attention, or maybe even they are ignoring this significant cost/savings.