Like the title said, I’m interesting in figuring out how many roads there are in the world, though the US and Europe would be a good start.
This isn’t just an idle question. About 1990 a very common metaphor for the complexity of ICs was comparing the number of internal signals to the road network in the Bay Area, and then for all of California. That was a bunch of Moore cycles ago, and the number of signals is a lot bigger now - but as big as the US, the entire world, or more?
As a working definition of road, I’d take a named entity, so I’d be happy to count the typical Boston road, which changes names every few feet, as several. I’m only interested in order of magnitude calculations here. I’ve searched for it and found no good answers. I think I could probably come up with a total length, but that is not very useful.
Anyone ever seen this number? I suspect that the people who do maps for GPS systems have it.
BTW, the number of transistors in all the microprocessors produced in the US this year is roughly the same as the number of ants in the world.
As an order-of-magnitude guess, I’d think that there would be around 10 people living on an average road (1 seems too low; 100 seems too high). That would mean 500 million to a billion roads
I actually have this data. Sort of. My company (among other things) performs routing functions for telephone book deliveries and for a mere $1,300-odd we purchase the entire Carrier Route Information Systems package from the USPS, a listing of all street segments delivered by the Post Office. While it is not inclusive of all roads, it is inclusive of all roads with addresses (yes, there is a difference and yes, the USPS keeps track of all this).
While I’m not going to pour through the entire dataset, the CRIS information for the US comes to 7,596,356 rows of data of which appx. 10% are considered “garbage” for our uses - Apartment complexes broken into building numbers, streets with “RR” and “HC” designations, etc. Many streets are counted multiple times as they are delivered on multiple carrier routes, which results in an additional 30% line loss (however, some areas can compress up to 60-70% - Manhattan for one as a number of buildings are given their own zip code for their one address). So, my best (pretty educated) guess would be that there are, at most, 4,700,000 separate roads in the US, Guam, and PR.
The USPS does not keep statistics as to how many addresses are on each specific street segment so I can’t give you that info (or pull it out of my azz). However, Giles estimate of 500M to 1 billion roads seems very high: Assuming that the rest of the world is as congested as the US (4.7M roads on 6% of the worlds’ land surface), this would amount to around 80,000,000 roads.
100 seems way too low, to me, which would explain JohnT arriving at a lower estimate. A few very large numbers will skew the mean - think of how many people live on Park Avenue in Manhattan, or one of the major roads in Tokyo, or Mexico City. Surely some are six figures, possibly even heading towards seven.
Thanks, all. I delivered mail one summer, so I’m familiar with USPS routes, and 4.7 million roads sounds pretty reasonable. I agree that 10 - 100 people per road is way too low. Around where I live we have cul de sacs called courts that are one block long, and they have 10 houses on them. Rural roads with low density are long, so even they would be way over 10.
I wonder if Google maps has some meta-information. I’ll check.
Since GorillaMan brought up Park Ave, to explain what I meant in regards to “compression” (mentioned in post 3): Park Ave is 1 street going through 12 zip codes, broken up into 307 separate deliverable segments, on 92 separate carrier routes. This blows away the “60-70%” ratio mentioned above, but Park Ave is a comparative rarity, even for Manhattan.
Yes, I know that there are roads (like Park Avenue in New York) with a lot of people living on them. On the other hand, there are a lot of roads with no one living on them. So if the databases mentioned cover street segments delivered to by the USPS, there would be a lot of roads in the US not in the databases. Of course, most will be short, unsealed, and sometimes not much wider than a footpath, but they are roads. They would include the short roads in rural areas going from the county road that the USPS delivers to, up to the farm house. Since there are around 2 million farms in the US, you need to add at least 2 million to the total. In addition, population density is lower in the US than in the rest of the world, and that pushes things up a bit.
Part of the problem is that the term “road” is fuzzy and ill-defined.
However… (surely you knew I was going to add an “however” )
In addition to the USPS roads, in our routing and mapping processes, we add all non-USPS roads that match your criteria above: Access roads, alleys, Farm-to-Market roads, Forest Service roads, etc. (This way we can guarantee our clients the most complete coverage possible. Or at least make that claim in our proposals. )
Looking at the datasets for all of our deliveries conducted since January 2006 I note:
2,195,348 USPS street segments.
117,934 “additions” (in our companies parlance)
For a non-USPS road rate of 5.4% (rounded) of USPS roads.
With a quick Google search I found this site. (37 kB pdf) It gives the information for 7 countries, but unfortunately it is for 1993. I’ll keep looking and see if I find anything more recent.
Summary:
US - 3,905,000 total miles, all roads (rounded figures - does not defined a “road”)
Mexico - 153,000 miles
Canada - 528,000 miles
UK - 225,000
Sweden - 85,000
Germany - 395,000
France - 504,000
Japan - 704,000
This is wonderful. We are much closer to the truth than was Bob Dylan’s answer (thanks, Ludovic) to his own question. Teams of Teeming Millions are just now delving into Robert Plant’s plaintive, stolen plea, “How many more times, treat me the way you do?”
NASA has gotten us much closer to the answer for, “How much did Io weigh, boys?” than before. It’s a lot more than “a Washing ton, boys.”
On the same FHWA (Fed Highway) site I found the same chart with 1999/2000 figures, although it is in kilometers. (Here)
There is another page with the data for the US in 2004 split by state here.
If you really want to get into the subject, here is an indirect link to a 930 kB ZIP file of World Road Statistics. Unfortunately the most recent data is for 1989 and for each country they give data for several years. It would therefore be tricky to come up with an easy answer to your question, but at least it appears that the data is there.
Sadly these sites just give mileages and do not mention men walking down them before anyone tells him anything.
The CIA world factobook gives miles of roads for each country and breaks them down into paved and unpaved. Not what the OP was asking, but perhaps useful for sampling.
The real question is, How many of them must one walk down before you call… well you know.
Worldwide it is hard to say. In many places roads are so ill-defined that I don’t think there is an answer. When some friends lived in Kampala, Uganda, their road was more of just a narrow dirt path leading to a group of 4 or 5 houses.
When does a dirt path become a road. I would guess most roads in the world do not have names when you think about the vastness of the developing world and mega-cities like Karachi.
I wonder how many roads don’t actually exist. Now, I don’t mean Lonely Street or the Yellow Brick Road. I mean roads that are shown on maps, but either never existed, or have been torn up for parks and buildings. When I first moved into this house, city maps did not show my street. It had been here for 15 years. Around the corner, though, the map showed Hickory Court at the end of Redwood Lane. It’s not there, though the new maps still show it. The developer ran out of money before building the street. Three or four times a year, folks pull over on the street to ask me how to get to Hickory. At first, I thought it was a fool’s errand, like sending a kid out to get a bucket of steam. Now, I figure they’re canvassers or evangelists. I don’t know whether to prolong their confusion or tell them the truth. It’s a big woods back there, and the thought of a missionary wandering in the wilderness is tempting.
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