This is only one example but in Milwaukee, where I live, a large pension scandal from the 90’s helped decimate the city finances which has lead them to stretch road lifespans way past where they should. Potholes and poor road quality everywhere. They focus on fixing up main thoroughfares.
I moved to a more rural suburb and the roads are top notch with regular replacement and patching. A fiscally responsible local government makes a big difference. The state covers state highway repairs which are some of these major thoroughfares. The local governments are responsible for their own road funding.
Why are urban roads worse in the US? Two ideas I have been wondering about are (1) higher opportunity cost to have a highly-used road closed for repairs means it’s worth it to live with worse conditions for longer, and (2) something about politics directing more road funding to rural areas.
Maybe slower speeds in cities have a role to play too? I would guess the comfort of 30mph vs 60mph at the same IRI is quite different, and so there's less demand for lower IRI in cities.
I'm sorry to say, but a big part of it as well are the minority populations that live in these areas being discriminated against by the US system. You get more funds from the gov't for golf courses than you do for inner city roads.
I think utility placement is likely to be a major factor in urban roads as well. Rural roads are more likely to have any underground utilities located on the shoulder, while urban roads typically have more underground utilities in the right of way, and a greater likelihood of having those utilities placed under the pavement.
If the utilities are under the pavement, the road will need to be opened up if they need maintenance. Patching utility access holes in pavement doesn't typically end with a high quality surface in my experience.
Road quality in Scotland is very good. They use mostly American design standard recoded and standardized under eurocode, but they take it seriously and they design roads with very long service life. They tend to also use much more porous and permeable pavement and a rougher surface coating due to typical bad weather there, but their roads remain very smooth in terms of driving. Their design curves and spirals are generally very good. And they don't tend to neglect their roads anywhere near the degree you might find, say, in southern California. Which is rather ironic since California and the US practically invented modern road design and engineering.
European countries also have higher fuel taxes to fund road maintenance. When Ohio raised the state taxes a couple years ago, there was much wailing and mashing of teeth.
If you think roads in California are shockingly bad you haven't visited other developed and developing countries that make most US roads look perfect. The road quality where I am from in Montreal is probably 5 times worse than most US cities.
Does it snow in Montreal? Does it go down below 0C/32F? I've heard it does. Do you use snow plows, road salt, maybe road sand? Those are hell on roads. I know it is possible to maintain good roads even in such conditions as in Minnesota, but it costs a bit.
Re warm places having poor quality roads: neither California nor New Mexico are exclusively warm places. They both have a lot of mountainous roads with typical winter weather-related issues. Perhaps that accounts for the explanation as to why their roads aren't in great condition, despite them being associated with warm weather.
Possibly, although the fact that the pattern repeats on the city level seems to push against this explanation. California And New Mexico also don't salt their roads the way that places in the northeast/midwest do.
I tend to think there's a few winter-related issues that result in roads being kept in overall better condition. As road roughness increases, so does the severity and frequency of plow damage to that road, sometimes resulting in spot repairs to the road surface. If these smooth spot repairs are overwhelmingly in the location of the worst sections of roadway, this will bias the average IRI to be better.
Additionally, I would love to see data on the schedules for highway resurfacing and how they vary among jurisdictions: if areas with significant winter resurface their highways more frequently (to avoid as much seasonal damage), this would also bias the highway IRI to be better.
Hmm, about the "Why are urban roads surprisingly poor?" thing... if I had to guess, maybe it's related to how road damage works?
Namely, road damage scales with the 4th power of a vehicle's weight -- a 10 times as heavy vehicle does *10 000* times as much damage to the road. So if say just 1% of vehicles in an urban area are busses, with 99% as cars, while 100% in a rural area cars... then, if they handle an equal number of vehicle miles, say 100, the rural roads take 100*1 = 100 points of damage, while the urban roads take 1*10 000 + 99*1 = 10 099 points of damage. That's a lot of damage!
But of course, things aren't equal, urban roads tend to be driven on more, since more people live there. So things are even *tougher* for urban roads! There's lots of little things like that once you start thinking about it: cars in rural areas tend to be driven like twice a day, between work and home, while busses tend to drive around all day providing consistent service, but also unfortunately using the road while they're at it. It's more difficult and expensive to shut down an urban road than a rural one for repairs; people will complain about the noise, things are more cramped so it's harder to bring in heavy machinery, more people are affected by the traffic disruption, etc.
But, the biggest thing is probably that 4th power rule. Busses are great, for example, but the 4th power law is simply so strong that a city adopting busses will probably have to spend *more* money on road maintenance, not less. Same with say, replacing people buying groceries in lots of big gas guzzling SUVs, with them instead walking to a supermarket that gets its stock delivered by a single 18-wheeler heavy truck -- so much better in so many ways, but the 4th power law is so unforgiving that the city will likely have to spend *more* money on road maintenance. It's counterintuitive... but the very thing that makes cities great, like public transport and walkability, also means they are in a way even *more* dependent on their roads than ever. Or at least more dependent on their road maintenance department.
(Miscellaneous notes:
1. The 4th power law is actually about vehicle weight *per axle*, not raw weight, so that's why an 18 wheeler heavy truck and a normal bus can cause comparable amounts of damage;
2. The 4th power thing is just a midpoint estimate, it can actually vary between a 2nd power and 6th power depending on the circumstances, meaning a 10 times axle weight truck can actually cause *one million times* as much damage;
3. If vehicles were taxed for road maintenance proportional to the damage they cause, it'd effectively be a tax on trucks and busses. For every 1 cent you'd charge a car, you'd charge $100 to a truck or bus that has 10 times the axle weight, while motorcycles and the like would be taxed at 0.0001 cent.)
California's haven't design formula uses the 4th-power role for calculating average daily traffic, but it converts the total lifetime traffic to a "Traffic Index" which is based on the total traffic raised to the 0.119 power.
And California's design standards *work*, as long as the estimated traffic it's close to the actual traffic, and routine maintenance actually occurs and is done properly. I'd estimate that almost 100% of California roads in bad condition haven't been maintained properly - they're rarely built poorly, and rarely is the traffic seriously underestimated. Road maintenance budgets are easy to trim a little too much when a government has fiscal trouble.
It sounds like we need a comprehensive road quality index that includes all roads in the nation and then let the media get ahold of it. I am a firm believer that indexes can create transparency and competition. No city or state will want to be on the bottom of the list.
And I have no idea why Time magazine in 2000 wrote: “ European highways actually carry more traffic and considerably heavier truck weights than US roads”
More traffic? Maybe, but I think that it is likely the opposite.
I would throw in that the roads in Metro Detroit are TERRIBLE. Like, abysmal, you can hardly call some stretches a road anymore.
The problem? Population decline leading to tax revenue decline plus rampant corruption (especially in the D). There are far too many miles of roads to be taken care of with the money that the state will give out for it per year.
Even as gentrification continues around the downtown area, it still wont be enough to maintain all of the roads.
Illinois toll roads were supposed to revert to free after they are paid off. They are under constant construction, even where the construction isn’t needed. Therefore, they are never paid off, and provide for high-paying patronage union jobs. Get it yet?
Having lived in Detroit, Madison WI, NYC, SF, LA, Ft Lauderdale, and many more, my theory (whatever it's worth) is that city road quality and the variance of that quality are not related to any physical factors at all (weather, usage, construction methods, etc.), but purely the result of investment priorities. One striking example for SF: the actual budget for road maintenance is so inadequate, that bond issues are put to referendums on a regular basis to fix roads. Basically the actual budget (the "savings account") for road maintenance is effectively zero such that they need to get regularly out the credit card and take out a high interest loan to do that maintenance.
And my time in LA shows an even worse situation: not only is the regular budget (savings) for road maintenance similarly low as SF - but LA never even takes out loans for repair. They just let them slowly decay. There seem to be more large private developers (building new apartment and retail complexes) that pay for road improvements than the city itself, because they often want to underground overhead wires for these developments, which entails digging up roads and sidewalks, which then are refinished. So in LA, you have these little short sections of really nice road surfaces, interrupted by really bone-jarringly horrific ones in front of the more "tatty" built environments. And the really nicest roads are done by home owner associations in well off areas - again, privately funded.
A study that might be worthwhile and eminently doable, would be to look at different government budgets for regular road maintenance (not new construction) per mile of road. I suspect this data would correlate 100% with the road quality data.
I'd be curious to break down US road quality by 'who built it'. The standard in my area is for developers to construct roads at their cost and then dedicate them to the relevant jurisdiction. The roads in all subdivisions are therefore built by developers, as are a lot of the improvements to arterial roads necessitated by that development (new traffic signals, turn lanes, etc). Developer-built roads are technically constructed to local specs. I don't know if it makes a difference in reality, but you'd expect a developer-built road to have more corners cut than a publicly- built road, and less incentive to be concerned with long term maintenance requirements or durability.
This is only one example but in Milwaukee, where I live, a large pension scandal from the 90’s helped decimate the city finances which has lead them to stretch road lifespans way past where they should. Potholes and poor road quality everywhere. They focus on fixing up main thoroughfares.
I moved to a more rural suburb and the roads are top notch with regular replacement and patching. A fiscally responsible local government makes a big difference. The state covers state highway repairs which are some of these major thoroughfares. The local governments are responsible for their own road funding.
Why are urban roads worse in the US? Two ideas I have been wondering about are (1) higher opportunity cost to have a highly-used road closed for repairs means it’s worth it to live with worse conditions for longer, and (2) something about politics directing more road funding to rural areas.
Maybe slower speeds in cities have a role to play too? I would guess the comfort of 30mph vs 60mph at the same IRI is quite different, and so there's less demand for lower IRI in cities.
I'm sorry to say, but a big part of it as well are the minority populations that live in these areas being discriminated against by the US system. You get more funds from the gov't for golf courses than you do for inner city roads.
Also, urban roads are used far more?
I think utility placement is likely to be a major factor in urban roads as well. Rural roads are more likely to have any underground utilities located on the shoulder, while urban roads typically have more underground utilities in the right of way, and a greater likelihood of having those utilities placed under the pavement.
If the utilities are under the pavement, the road will need to be opened up if they need maintenance. Patching utility access holes in pavement doesn't typically end with a high quality surface in my experience.
Possibly there's just so much of them - suburban sprawl means the tax base per mile of road is less than in more densely populated European cities
Also urban local governments in the US are notoriously mismanaged.
Road quality in Scotland is very good. They use mostly American design standard recoded and standardized under eurocode, but they take it seriously and they design roads with very long service life. They tend to also use much more porous and permeable pavement and a rougher surface coating due to typical bad weather there, but their roads remain very smooth in terms of driving. Their design curves and spirals are generally very good. And they don't tend to neglect their roads anywhere near the degree you might find, say, in southern California. Which is rather ironic since California and the US practically invented modern road design and engineering.
I'd recommend researching Icelandic roads - I've always been impressed by the state of their roads (I'm from the US northeast, for comparison).
European countries also have higher fuel taxes to fund road maintenance. When Ohio raised the state taxes a couple years ago, there was much wailing and mashing of teeth.
But a lot more roadwork is getting done now.
In my experience, rural roads in Ireland are significantly worse than rural roads in the US.
If you think roads in California are shockingly bad you haven't visited other developed and developing countries that make most US roads look perfect. The road quality where I am from in Montreal is probably 5 times worse than most US cities.
Does it snow in Montreal? Does it go down below 0C/32F? I've heard it does. Do you use snow plows, road salt, maybe road sand? Those are hell on roads. I know it is possible to maintain good roads even in such conditions as in Minnesota, but it costs a bit.
Re warm places having poor quality roads: neither California nor New Mexico are exclusively warm places. They both have a lot of mountainous roads with typical winter weather-related issues. Perhaps that accounts for the explanation as to why their roads aren't in great condition, despite them being associated with warm weather.
Possibly, although the fact that the pattern repeats on the city level seems to push against this explanation. California And New Mexico also don't salt their roads the way that places in the northeast/midwest do.
I tend to think there's a few winter-related issues that result in roads being kept in overall better condition. As road roughness increases, so does the severity and frequency of plow damage to that road, sometimes resulting in spot repairs to the road surface. If these smooth spot repairs are overwhelmingly in the location of the worst sections of roadway, this will bias the average IRI to be better.
Additionally, I would love to see data on the schedules for highway resurfacing and how they vary among jurisdictions: if areas with significant winter resurface their highways more frequently (to avoid as much seasonal damage), this would also bias the highway IRI to be better.
Hmm, about the "Why are urban roads surprisingly poor?" thing... if I had to guess, maybe it's related to how road damage works?
Namely, road damage scales with the 4th power of a vehicle's weight -- a 10 times as heavy vehicle does *10 000* times as much damage to the road. So if say just 1% of vehicles in an urban area are busses, with 99% as cars, while 100% in a rural area cars... then, if they handle an equal number of vehicle miles, say 100, the rural roads take 100*1 = 100 points of damage, while the urban roads take 1*10 000 + 99*1 = 10 099 points of damage. That's a lot of damage!
But of course, things aren't equal, urban roads tend to be driven on more, since more people live there. So things are even *tougher* for urban roads! There's lots of little things like that once you start thinking about it: cars in rural areas tend to be driven like twice a day, between work and home, while busses tend to drive around all day providing consistent service, but also unfortunately using the road while they're at it. It's more difficult and expensive to shut down an urban road than a rural one for repairs; people will complain about the noise, things are more cramped so it's harder to bring in heavy machinery, more people are affected by the traffic disruption, etc.
But, the biggest thing is probably that 4th power rule. Busses are great, for example, but the 4th power law is simply so strong that a city adopting busses will probably have to spend *more* money on road maintenance, not less. Same with say, replacing people buying groceries in lots of big gas guzzling SUVs, with them instead walking to a supermarket that gets its stock delivered by a single 18-wheeler heavy truck -- so much better in so many ways, but the 4th power law is so unforgiving that the city will likely have to spend *more* money on road maintenance. It's counterintuitive... but the very thing that makes cities great, like public transport and walkability, also means they are in a way even *more* dependent on their roads than ever. Or at least more dependent on their road maintenance department.
(Miscellaneous notes:
1. The 4th power law is actually about vehicle weight *per axle*, not raw weight, so that's why an 18 wheeler heavy truck and a normal bus can cause comparable amounts of damage;
2. The 4th power thing is just a midpoint estimate, it can actually vary between a 2nd power and 6th power depending on the circumstances, meaning a 10 times axle weight truck can actually cause *one million times* as much damage;
3. If vehicles were taxed for road maintenance proportional to the damage they cause, it'd effectively be a tax on trucks and busses. For every 1 cent you'd charge a car, you'd charge $100 to a truck or bus that has 10 times the axle weight, while motorcycles and the like would be taxed at 0.0001 cent.)
California's haven't design formula uses the 4th-power role for calculating average daily traffic, but it converts the total lifetime traffic to a "Traffic Index" which is based on the total traffic raised to the 0.119 power.
And California's design standards *work*, as long as the estimated traffic it's close to the actual traffic, and routine maintenance actually occurs and is done properly. I'd estimate that almost 100% of California roads in bad condition haven't been maintained properly - they're rarely built poorly, and rarely is the traffic seriously underestimated. Road maintenance budgets are easy to trim a little too much when a government has fiscal trouble.
Interesting article.
It sounds like we need a comprehensive road quality index that includes all roads in the nation and then let the media get ahold of it. I am a firm believer that indexes can create transparency and competition. No city or state will want to be on the bottom of the list.
And I have no idea why Time magazine in 2000 wrote: “ European highways actually carry more traffic and considerably heavier truck weights than US roads”
More traffic? Maybe, but I think that it is likely the opposite.
Heavier trucks? Are you kidding me?
I would throw in that the roads in Metro Detroit are TERRIBLE. Like, abysmal, you can hardly call some stretches a road anymore.
The problem? Population decline leading to tax revenue decline plus rampant corruption (especially in the D). There are far too many miles of roads to be taken care of with the money that the state will give out for it per year.
Even as gentrification continues around the downtown area, it still wont be enough to maintain all of the roads.
Illinois toll roads were supposed to revert to free after they are paid off. They are under constant construction, even where the construction isn’t needed. Therefore, they are never paid off, and provide for high-paying patronage union jobs. Get it yet?
My family accuses me of being “ a master of strange and little known facts”. Thanks for adding to my list.
Having lived in Detroit, Madison WI, NYC, SF, LA, Ft Lauderdale, and many more, my theory (whatever it's worth) is that city road quality and the variance of that quality are not related to any physical factors at all (weather, usage, construction methods, etc.), but purely the result of investment priorities. One striking example for SF: the actual budget for road maintenance is so inadequate, that bond issues are put to referendums on a regular basis to fix roads. Basically the actual budget (the "savings account") for road maintenance is effectively zero such that they need to get regularly out the credit card and take out a high interest loan to do that maintenance.
And my time in LA shows an even worse situation: not only is the regular budget (savings) for road maintenance similarly low as SF - but LA never even takes out loans for repair. They just let them slowly decay. There seem to be more large private developers (building new apartment and retail complexes) that pay for road improvements than the city itself, because they often want to underground overhead wires for these developments, which entails digging up roads and sidewalks, which then are refinished. So in LA, you have these little short sections of really nice road surfaces, interrupted by really bone-jarringly horrific ones in front of the more "tatty" built environments. And the really nicest roads are done by home owner associations in well off areas - again, privately funded.
A study that might be worthwhile and eminently doable, would be to look at different government budgets for regular road maintenance (not new construction) per mile of road. I suspect this data would correlate 100% with the road quality data.
I'd be curious to break down US road quality by 'who built it'. The standard in my area is for developers to construct roads at their cost and then dedicate them to the relevant jurisdiction. The roads in all subdivisions are therefore built by developers, as are a lot of the improvements to arterial roads necessitated by that development (new traffic signals, turn lanes, etc). Developer-built roads are technically constructed to local specs. I don't know if it makes a difference in reality, but you'd expect a developer-built road to have more corners cut than a publicly- built road, and less incentive to be concerned with long term maintenance requirements or durability.
Brian, great writing as always. I don't know if you have seen the "Report Card For America's Infrastructure". It has some great data by state, by category, etc. Over multiple years. Enjoy. https://infrastructurereportcard.org/cat-item/bridges-infrastructure/