Shallow American Roads

While browsing through the alt.folklore.urban usenet group, I noticed a debate raging over the question of how deep American roads are. Apparently (so the urban legend goes) American roads can only be built to a fairly shallow depth in order to make the land under them more easily reclaimed for farming. By contrast, European roads are built to a much deeper depth. As a consequence, European roads are much more durable than American roads and need fewer repairs. The usenet group didn't appear to have reached any conclusion about the validity of this claim, but I can't imagine it's true. I think the frequency of road repairs is mainly a function of weather conditions (does the ground freeze and thaw a lot) and the amount of traffic on the road. I can't find any references on Google to American laws stating that roads have to be kept shallow for the benefit of future farmers.

Exploration/Travel Urban Legends

Posted on Tue Oct 19, 2004


I do know that, for example, the German Autobahn is thicker/deeper by far than a US motorway would be, and the depth is specifically to make the road more durable and reliable. I have never heard of there being the reverse, a law forcing the roads in the US to be thinner, however.
Posted by Frookah  on  Tue Oct 19, 2004  at  02:02 AM

Posted by coit  on  Tue Oct 19, 2004  at  02:31 AM
I worked in asphalt over the summer and the truth really is that it depends. Thinner roads are lower costing and so America being a much larger nation would therefore require more paving so it would be logical to assume that these roads would be thinner, this would allow crews to move more rapidly and provide lower cost roads to and through less populated areas. However, in more populated areas and on interstate highways there are certain standards of thickness to which the road must be paved. Often times when a crew goes into repave an area they will typically 'mill' the street - this just increases the surface area of the actual road, and leave much of the remaining road intact. Also some roads have a roadbase applied to allow for the shifting of the soils, this may or may not be counted in your road thickness gauge. As for whether they are more durable that also depends. A certain mixture of asphalt called SMA actually contains shreded newspaper in it - almost all the freeways are constructed using this. This stuff is for all purposes bulletproof. Some experimental mixtures that are called porous asphalt exist, there is not enough information to determine whether they decrease pollutants in runoff or that such roads are more resistant or weak to cold frosts and the changes in volume caused by water freezing, however it does seem to hold up almost as well as conventional asphalt. As far as conventional asphalt goes there are quite a number of mixtures some of these are more rocky and some of these are more like peanut butter. It really depends on the aggregate and the oil for that matter used to create it. The rocky mixture which consists mostly of 1/2 and 3/4 inch pebbles is typically resigned for high stress situations. Oils really are what determine how well the road holds up. The more tacky the oil is the better it holds the aggregate together, in the case of the SMA the paper absorbs the oil causing a higher density to be present per volume thus increasing durability. If the European roads are thicker, this could be because their current civilization has been in place longer and so the thickness of their roads has increased and if this is not the sole reason i would guess that because the pay an incredible amount more for their oil than we do that they user a lower quality oil in high quantity.
Posted by Jared  on  Tue Oct 19, 2004  at  02:45 AM
Actually, the issue is one of durability. When European governments issue a contract for a road, it has to be guaranteed for 40 years. In America, it has to be guaranteed for 10. As a result, European roads are built with a deeper foundation, which provides a more stable base and leads to fewer breaks and potholes--thus cheapening the maintenance costs. More expensive up front, less expensive long term. It is part of why they can even have roads like the autobahn; a pothole at 100mph can ruin your whole day.
Posted by Ron T  on  Tue Oct 19, 2004  at  07:39 AM
I've heard the same thing as Ron T. - the difference in road construction is that Europeans simply consider it important to pay extra for more durable roads.
Posted by Matt  on  Tue Oct 19, 2004  at  09:59 AM
But, in some places, wouldn't it be difficult to dig too'd run into pure rock, or you could contaminate aquifers...

So, wouldn't that have something to do with it? Plus, even if you built a really thick road for durabilty, if you got a single tiny crack in the rdwy, and then had snowfall, which filled in the crack and then froze overnight, it would make the crack bigger. So neither is better? I'm confused.
Posted by Maegan  on  Tue Oct 19, 2004  at  10:16 AM
They made a new road here where I live and I drove by it every day. It was a divided highway extension. I'll bet the foundation was 6 feet deep, based on just seeing how deep they were making it. Maybe that's true for past roads, but I'm inclined to believe Jared when he says it varies.
Posted by Bill B.  on  Tue Oct 19, 2004  at  11:10 AM
I hope the US adopts Europe's strategy, because the roads in Massachusetts seem to be in a constant state of repair.
Posted by john  on  Tue Oct 19, 2004  at  03:12 PM
american roads are thinner because they are cheaper to build. americans generally build or improve roads based on projected usage trends at the time of completion, which is usually two or three years. but these projections generally tend to be on the "light" side, meaning that by the time the road or improvement is completed, it is time to do it again in order accommodate current traffic levels (see the I-75/I-85 "improvement" projects in atlanta, ga. during the 80's and 90's for more about this). the result is that the companies who build and improve roads get to soak the taxpayers for tons of money because of the constant "improvement" cycle. this goes on and on in most major cities (l.a., new york, s.f., houson, dallas, chicago).

in europe, on the other hand, when a road is built or improved, it is done using traffic projections that extend to twenty years. the roads are built to a thicker depth so that they last longer with fewer repairs necessary. over the long term, europeans save tonnes of money because their road systems require fewer repairs and fewer improvements.

i have driven in many major cities in the untied states, and have encountered major highway improvement projects in every major city almost every time i have done it. even in my home town, improvement projects are a fairly constant annoyance (rush hour, anyone?). i have also driven in france, belgium and germany. the road improvement projects are few and far between. it is truly amazing! the end result of all of this is that we taxpayers lose tonnes of time driving on roads that constantly require improvements, and we lose tonnes of money because we are paying for all of those improvements. the companies doing all of this work are laughing all the way to the bank.
Posted by bugbear sloth  on  Tue Oct 19, 2004  at  07:58 PM
according to a NPR story that I heard, it's ALL about the guarentees that Ron T mentioned. but the decided norm for the length is influenced by country size and economics. here in the US, we like to build stuff and we have lots of land to connect. building stuff provides jobs. roads that last too long are bad for our economy. the article stated that over a period of time, the cost is about equal. but in the shorter term, thinner cheaper roads do more to stimulate economic growth than more permanant ones. i work for a construction mgt. dept. at a big 10 college and we play a balance game between building a quality road for safety purposes and building a road thin enough that it doesn't cost billions to repair or replace as the campus design changes.
Posted by chrees  on  Thu Oct 21, 2004  at  04:48 PM
I remember seeing a news program on this topic a few years ago. It supports what Ron was saying.

Think about it; how do American roads get made? By the bidding system. The LOWEST bid wins. In order for the contractor to do the work (at the Lowest bid price) they use to cheapest materials available.

It would make more sense to invest more in our roads to begin with. I don't buy the weather arguement. I live where we have extremes in temperature, but don't they also have winter in Europe? (Cold weather & snow, etc)

Anyways, take care & drive safely,
Posted by dam9191  on  Mon Oct 25, 2004  at  03:06 AM
One other point to consider. In Europe the roadwork has to have a ten-year warrenty. In America, there is too much political capital in new roads and/or repaired roads. Too many political favors to political donors or other supporters. The roads in Scandanavia have the warrenty and the climate there is at least as bad as you can find here.
Posted by Christopher Cole  on  Sat Nov 13, 2004  at  08:47 PM
All of the above are summarily true. Junky roads leads to more repairs and more automobile fixes. Bureaucratic stuff is cyclic and virile. Once a country falls into it, the status quo is just too powerful to overcome. I've driven in both Taiwan and here in California and gotta say, the road quality's about the same... On a scale and in consideration of the advancement of the U.S, we have pathetic public road system. All of this, much like any other major issue, is merely caused by political correctness. There's simply too much of it for this country to function properly. I love my country but for the love of ourselves, we need a change, and not just in terms of a president...
Posted by Psycho Michael  on  Sun Mar 08, 2009  at  07:21 AM
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