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Two Dimensional Road

There are no traffic jams in Ring City
  (+3, -7)
(+3, -7)
  [vote for,
against]

A new way to design a city:

Buildings are arranged in a 1 km wide ring with an inner diameter of 10 km. In the built-up area cars are allowed on radial roads only. Circular roads inside the ring are dedicated to cyclists and pedestrians. The inner circle is completely paved over, and becomes a single, two dimensional road. A strip 200m wide or so provides ample parking on the perimeter of the paved circle. On the outer side of the ring a green belt provides recreational space.

To get to your destination simply drive there in a straight line. There are no traffic lights, no lanes, no road markings and no road signs. Just a single flat surface. There are only two important traffic rules: a) You must not make sharp turns unless there is an obstruction b) If a vehicle crosses your path from the right you must slow down and give way.

For extra safety, a 30 km/h (20 mph) speed limit applies. There is no stopping at traffic lights, so even at such modest speeds the longest journey (dissecting the circle) takes only 20 min (perhaps 30 min in heavy traffic), which is pretty good for a city of 0.5m - 1m inhabitants.

Between 1am and 5am the speed limit is lifted but fast cars must be equipped with red and green starboard/port lights.

Public transport is provided by a single circular metro line within the ring, connecting any two points in less than 30 min.

Traffic jams are unlikely because, as opposed to linear roads, there are no bottlenecks and obstructions can be easily circumnavigated. Noise, air pollution and through-traffic is segragated from the inhabited part of the city, which becomes human-friendly again.

Eveyone is happy.

The petrolheads are happy because they still have their god-given right to drive their car. In fact, the concept of "driving freedom" would be taken to a whole new dimension. And they would finally stop moaning "build more roads".

The tree-huggers are happy because they can choose to live in the ring area and green belt only and encounter very few cars. They too would stop moaning "are you going to cover the whole country in concrete?", because it already is.

Oh, and don't forget your compass in foggy conditions.

kinemojo, Mar 16 2006

Arc de Triomphe http://www-scf.usc....ce/222-2285_IMG.jpg
Half baked in Paris [kinemojo, Mar 16 2006]

Mesh City Mesh_20City
[Loris, Mar 17 2006]

Traffic Scrum http://pics.livejou..._caeli/pic/0011x9dg
In GLORIOUS electronic crayon! [Galbinus_Caeli, Mar 18 2006]

Distribution of cars http://sixpop.com/i...images/85587018.jpg
Each point is a car. This models assumes that an identical line of cars travels between each possible pair of spokes [kinemojo, Mar 20 2006]

Traffic paths http://sixpop.com/i.../images/5379282.jpg
A circle with 36 nodes showing all possible paths [kinemojo, Mar 20 2006]

Magic roundabout http://en.wikipedia...ki/Magic_roundabout
[kinemojo, Mar 20 2006]


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Annotation:







       Interesting idea, but in healthy cities, real estate in the center is the most valuable. I doubt many would be prepared to give up that source of revenue very easily by converting such a large piece of it to tarmac.   

       I also have some major doubts about the safety of this. Most cities have smaller open areas (squares, piazzas, etc.), and while these work well for random pedestrian traffic, they all enforce regular traffic laws for the vehicles.
DrCurry, Mar 16 2006
  

       >>In healthy cities, real estate in the center is the most valuable. I doubt many would be prepared to give up that source of revenue very easily by converting such a large piece of it to tarmac.<<   

       The assumption here is that this is a planned city such as Milton Keynes.   

       First you buy some cheap land in a unbuilt area. Then you build the tarmac circle and infrastructure aroud it. Then you sell the real estate. Planning reguations would not pemit building on the tarmac circle, because technically it's a road.   

       As for real estate values, average jouney times are independent of location, contrary to traditional cities. Thus real estate values are the same everywhere (neglecting fluctuations due to other factors such as housing quality)
kinemojo, Mar 16 2006
  

       >>I also have some major doubts about the safety of this<<   

       I've tried to address this. See description.   

       Remember that this area is much larger than a piazza and that vehicle density is lower.
kinemojo, Mar 16 2006
  

       >>Why doesn't the inner disc just rotate ? Then it could be a park too.<<   

       Too utopian and high-maintenance.   

       A paved surface of 10km diameter is cheap, simple and effective.
kinemojo, Mar 16 2006
  

       I think it wouldn't be 2D, since drainage would be required. It would likely be a domed shape. Courses could be plotted using Satellite navigation, aircraft type beacons, compass, or radial coloured lines for important areas.
With a modest 4 inch (100mm) thick concrete paving, the volume of the paving would be 7.8 million cubic metres. Yikes.
Ling, Mar 16 2006
  

       Thinking about this further, I think you are making a fundamental mistake in assuming that cities are for cars, and should easily accommodate them.   

       What I like most about New York, London and Paris is that they are cities for pedestrians, and can be easily navigated on foot. Setting aside such a large amount of space for traffic gnaws away at the main point of having a city in the first place.
DrCurry, Mar 16 2006
  

       //A paved surface of 10km diameter is cheap, simple and effective.//
I'd agree with you except for the words 'cheap', 'simple' and 'effective'.
  

       Surface area of circle city road : 78539816 m^2   

       Access Road - full construction (25/70/150) surfacing according to pavingexpert.com : 42.75 ukp/m^2 (100m^2 rate)
(Lets halve that for bulk rates : 20 pounds/m^2)
  

       Cost of installing circle city road:1,570,796,320
Thats over 1.5 Billion pounds.
  

       For comparison, the Humber Bridge, which cut 50 miles off journeys around this river, cost 98 million, opening in 1981.   

       Also according to pavingexpert.com, "we estimate that a newly-laid tarmac driveway or pathway should give at least 10 years trouble-free service." Lets be generous and replace it every 20 years. Overlay rates are 11.50 ukp/m^2, - lets call that 5. Cost per year of upkeep : 19,634,954 = 19.6 million pounds a year.   

       I'm also not particularly impressed with your topology. What if you want to get from one spoke to the next? You still will have traffic jams in the spokes anyway, so the busy areas will back up into the circle, blocking routes off and making it harder and harder to get in and out, never mind to the other side. If this spills out into the circle, then you'll have cars facing in all directions, all trying to get round each other. Nightmare.
Loris, Mar 16 2006
  

       >>With a modest 4 inch (100mm) thick concrete paving, the volume of the paving would be 7.8 million cubic metres. Yikes.<<   

       Nothing that hasn't been done before.   

       78.5 km^2 is the surface area of a 15,700 km long two-lane road.   

       Thus, for a population of 1m this would be equivalent to 15.7 m of road per capita.   

       The total length of paved highways in Germany is 656,000 km. (source: wikipedia). Population is 82.5m. Which means 7.9 m / capita, or half as much as in Ring City.   

       However, Germany suffers from chronic traffic jams which suggests undercapacity.   

       It need not even be paved in concrete because speeds don't exceed 30 km/h. Compacted sand would suffice.
kinemojo, Mar 16 2006
  

       >>Thinking about this further, I think you are making a fundamental mistake in assuming that cities are for cars, and should easily accommodate them.<<   

       I totally agree, DrCurry. Cities are not for cars. Unfourtunately, 95% of people who live in them, along with the politicians they've voted, don't share our opinion.   

       I have suggested a viable example of a car-free city elsewhere on the hafbakery (Mesh City). Unfourtunately, I don't think car-free cities have much of a chance of proliferating in our current car-loving cultural climate.   

       So the next best option is to accomodate cars, and at the same time make them as unobtrusive as possible, which Ring City is basically about.   

       Ring city would in fact be more pedestrian-friendly even than Paris or New York. I was thinking about pop densities in the region of 20,000/km^2 (once the "rink" is excluded). Unlike New York, the built-up area would suffer from no through-traffic whatsoever. Circular roads within the 1km wide ring are cyclist/pedestrian only. A single metro line (or Bus Rapid Transit) connects any two points in the city within 30 min.   

       >>Setting aside such a large amount of space for traffic gnaws away at the main point of having a city in the first place<<   

       The experts don't seem to think so. Every larger planned city built in the last 50 years (Brasilia, Milton Keynes, etc.) has given huge priority to the car.
kinemojo, Mar 16 2006
  

       >>Thats over 1.5 Billion pounds.<<   

       Assuming there are 1m people in Ring City and 600,000 cars, that's an investment of 2,500 pounds per car. Mortgaged over 30 years this means ca. 130 pounds per car per year.   

       Upkeep is 20m pounds per year, or 30 pounds per car per year.   

       Total is 160 pounds a year per vehicle. For the average motorist in the UK the tax collected on petrol alone exceeds this sum by a factor of 5.   

       Therefore, finance is not a problem I'd say.   

       >>For comparison, the Humber Bridge, which cut 50 miles off journeys around this river, cost 98 million, opening in 1981.<<   

       Inappropriate comparison. The Humber Bridge is just a tiny section of the UK's road network. On it's own, it would be completely useless. Give me a figure of how much the the entire road network cost to build, and divide that by the UK's population, and then we can talk about comparisons.
kinemojo, Mar 16 2006
  

       >>Just make a big ring road<<   

       I've never seen a ring road in any big city *anywhere* in the world, however wide, that doesn't suffer congestion. Ok, perhaps Singapore is an exception, but there they have very strict restrictions on car ownership.
kinemojo, Mar 16 2006
  

       >>as pedestrians in the circle would be exhausted targets.<<   

       Pedestrians woudn't need to use the circle. See my response to DrCurry.
kinemojo, Mar 16 2006
  

       I see no consideration of drainage. That much impermeable surface is going to shed a lot of water.   

       A moderately heavy rain, say 1cm/hr, you are going to have to deal with 78,000 litres of water.   

       Of course if you dish the center slightly and add a center drain, this might server to clean up the carnage from all the automobile collisions.
Galbinus_Caeli, Mar 16 2006
  

       Sounds like an awful lot of concrete and not much greenery. I don't think that I'd like to live there.
DrBob, Mar 16 2006
  

       >>This 'utopia' seems to be the exact opposite<<   

       There are parallels. Again, the ring is only 1km in width. As most of the traffic is confined to the circle, there would be plenty of greenery outside the ring, again, within a 15 min walking distance.   

       Ring City is an attempt in maximising quality of life, while accommoding car travel and avoiding congestion.   

       Mesh city did away with car travel alltogether, so you could see this as a less extreme example.
kinemojo, Mar 16 2006
  

       >>Sounds like an awful lot of concrete and not much greenery<<   

       Not more concrete than in an ordinary city (see numbers above). Only distributed differently.   

       Plenty of greenery on the outer side of the ring.
kinemojo, Mar 16 2006
  

       //It need not even be paved in concrete because speeds don't exceed 30 km/h. Compacted sand would suffice.//
So actually it is more dirt track than road? Cowpat city might be more appropriate after rain.
  

       //Inappropriate comparison. The Humber Bridge is just a tiny section of the UK's road network. On it's own, it would be completely useless.//
So would your cowpat.
What I neglected to mention about the Humber Bridge, was that it rapidly built up a massive debt, and yet it is only a tiny proportion of the cost of the patty. And I was quite conservative in the cost estimates, I think. I didn't include buying the land, levelling costs and so on...
Given that of the 113 square kilometres the city takes up, 78.5 are the central 'patio', these might be significant.
  

       Even with a high proportion of car ownership, the costs seem considerable, given that they are on top of all the other expenses, and the benefits are ... debatable.   

       I think your maths is also suspect. Given your number of cars, and 5% interest, 130 pounds/car/year is rate the debt grows at; if you want to actually start paying it off you'll need to pay more!   

       I notice you didn't respond to my other points about traffic jams in the radial roads spreading into the circle, and the potential for incredible snarls on the patio.   

       On the other hand, I imagine you could lay the patty quite efficiently, and with the ability to utilise the surface already laid. You'd set up your road-layer(s) to lay either concentric circles, or even better, a spiral in from the edge.
Loris, Mar 17 2006
  

       >>I think your maths is also suspect. Given your number of cars, and 5% interest, 130 pounds/car/year is rate the debt grows at; if you want to actually start paying it off you'll need to pay more!<<   

       5% interest is rather high. But even if you charged of the order of 500 pounds a year for every vehicle, eg. through petrol tax, it would be less than drivers are paying now, on average.   

       >>Even with a high proportion of car ownership, the costs seem considerable, given that they are on top of all the other expenses<<   

       The other government expenses are negligible. The ring area of the city will only require minor radial roads for the small levels of traffic expected.   

       >>I notice you didn't respond to my other points about traffic jams in the radial roads spreading into the circle, and the potential for incredible snarls on the patio.<<   

       I've given this some thought. Bear with me.   

       First of all, remember that the ring section is only 1km wide. Therefore, it will be possible to walk from the edge of the inner circle to the destination building in no more than 15 min, (typically 7 min). Few motorists will see the need to drive into the narrow radial roads. Most will simply park their car on the circle and walk the remaining distance. Instead of driving to a giant superstore car park and walking to the superstore for 7 min you'll drive to the circle perimeter and walk to a shopping mall for 7 min. Not much of a difference.   

       Secondly, by doing away with trunk road s alltogether and making the radial roads narrow and densely spaced (a bit like residential streets; remember they're only 1km long) you'll avoid large amounts of traffic spilling into the circle on the same spot.   

       Thirdly, the circle itself. I've been reading the book Critical Mass by Philip Ball (I recommend it to everyone) and there are a couple of excellent chapters on the fluid dynamics of pedestrian and car traffic flows.   

       Traffic behaves in a similar way to matter. When traffic levels are low it's like a gaseous state: Cars go about their business and rarely interact with each other. When traffic levels increase, it becomes like a liquid. Cars still flow freely but are restricted in their movement by adjascent cars.   

       The circle area is huge, so outside rush hours the traffic would be gaseous. People just drive off in a straight line and maybe slow down a couple of times on the way. Imagine the circle as a lake and the cars as boats. Recreational lakes don't seem to suffer from traffic jams, even when they're crowded.   

       What about rush hours? There are models of how pedestrian flows behave in crowded intersections. It turns out that when the density is high enough, the flow "self-organises" into a vortex, and pedestrians no longer take the shortest path. I assume the same would happen in the ring. It would self-organise into a giant roundabout. The direction would always be clockwise because driving in counter-clockwise direction would mean giving way more often. Under certain conditions, several interlocking vortices might even emerge.   

       I suppose that during rush hours, the flow of the naturally emerging vortex could be streamlined by prohibiting driving in the counter-clockwise direction. You could simply paint concentric rings on the tarmac to enforce this rule.   

       I don't know how much traffic would be needed until the "liquid" scenario emerges. Perhaps the circle is large enough never to reach that point, even at rush hours.
kinemojo, Mar 17 2006
  

       It is not valid to compare pedestrian traffic with vehicular. Pedestrians are moving at or near their maximum comfortable speed, cars are not. Pedestrians can make sudden stops or changes of direction in very short distances, cars cannot. Pedestrians can safely brush up against other pedestrians without damage, cars cannot.   

       Basically I see your city working this way. 7:30am. Everyone in the city hop in their cars points toward their offices on the opposite side of the city. (remember that the closer you get to driving directly across the center, the more destinations are on almost the same course). Then everyone simutaneously floors their accellerators screeching across the circle, careening madly in an attempt to avoid the other sleep deprived or caffiene crazed commuters. Somewhere near the center someone misses a twitch and the first crash happens. This is at the center of the circle, where more people want to cross, and where they are all going at their maximum speed, so they pile into the mass, which grows out from the center. Now drivers are going to attempt to avoid this mess by circteing it (clockwise) as closely as possible. Later additions to this circle mess are now outside the earlier circlers, so are blocking them in as they attempt to turn out from the center back toward their destinations, this leads to more crashes and an expansion of the pile of twisted metal at city center. Eventually the only cars able to move are those that are driving very slowly around the perimeter of the circle, stopping at each radial road to avoid being hit by those whose alarms failed to go off.
Galbinus_Caeli, Mar 17 2006
  

       While my view is not as apocalyptic as Galbinus_Caeli's, I still don't like the idea. Remember that the cost is in addition to all the other charges, not instead of. It would have to be a city-wide tax of motor-vehicles.   

       Perhaps if you strictly prevented anyone driving in the spokes (except deliveries, emergency vehicles, invalids etc) then you wouldn't jam these up. I suppose you could also have something fairly large in the centre, to avoid the demolition-derby effect.   

       But that swirling effect is horrible, even as a pedestrian. And any there-and-back or slightly anti-clockwise journey would become literally circular, essentially gaining around 15 km.   

       Perhaps it is just me. I don't have a car, and think cities would be generally better off if they didn't sacrifice so much to make it easier for them. So using almost 70% of the surface area for one big road isn't going to win my croissant. Good effort though.
Loris, Mar 17 2006
  

       >>remember that the closer you get to driving directly across the center, the more destinations are on almost the same course<<   

       Not so. Actually, traffic density is lowest in the center. See link.
kinemojo, Mar 18 2006
  

       [Kinemojo] That is for a traffic ring, not a circle. That makes the traffic in that algorithm revolve around the center, rather than charge straight across. The circle is also relatively small.   

       See my link for a picture of what the traffic pattern would be with only eight destinations. Just look at the joyous traffic scrum in the center
Galbinus_Caeli, Mar 18 2006
  

       [Galbinus_Caeli]   

       In your link the line *density* is actually lowest in the center.   

       See the link "Traffic paths". This is exactly the same picture as yours, except with 36 destinations. The difference in line density is even more pronounced here.   

       The link "Distribution of cars" is the same picture, except that solid lines have been replaced with dotted lines. This is the scenario you would see if traffic emerged from each destination at an equal and constant rate and distributes equally to the remaining 35 destinations. Here it's even more clear that traffic density at the center is lowest.   

       The scrum would only take place if a large number of cars crossed the center at exacly the same time, which is unlikely, given the size of the circle.
kinemojo, Mar 20 2006
  

       [kino] You are right, its not the exact center. More like a zone around the center. But that zone is filled with cars moving directly at each other at speed.   

       I say we get some one to mod this up in a driving/race game and see what happens. Make it a gambling game. Everyone pays two bucks to start. If they make it safely to their destination they get one dollar back. Of those who safely get there, the fastest 50% split the rest of the pot. Should be fun!
Galbinus_Caeli, Mar 20 2006
  

       This is ridiculous. You've made everyone as far apart as mathematically possible, and then called this a "pedestrian friendly" city? Not even remotely.   

       Consider: the built-up area in your example, including embedded bike and pedestrian paths, is (6^2 x pi)-(5^2 x pi) = 34.56 sq km. The maximum walking distance from one location to another - assuming no-one is insane enough to attempt to walk through the demolition derby in the center - is (2pi x 6km) = 37.70km. The average walking distance assuming uniform density is half that, or around 18.85km. The maximum driving+walking distance is 12km (10km across the pancake + 1+1km walking).   

       Take your ~35sqkm pedestrian-friendly built-up area, and build it all in the center, with a ring road around the outside. The diameter, and thus maximum walking distance from anyone to anyone, is 2 x sqrt(34.56/pi) = 6.63 km - which is 1/3 of the ~average~ walking distance in your example.   

       The average walking distance in this case is a little beyond my abilities - anyone want to have a go? [marked-for-engineering] But at a wild guess/hunch, it may in fact be r, or 3.32km = 1/6th of the average in your ring city, and about a ten minute bike ride at an easy pace.   

       The ring road circumference is 20.83km. Thus even the maximum driving distance is a mere 400-odd meters longer than in your example, and given how much closer everyone is on foot, likely to be driven far, far less often.   

       The maximum drive+walk (for someone equidistant from the center and the edge, with a destination the same distance opposite - any closer to the center and they might as well skip the drive and just walk) is 2(d/4) + c/2 = r/2 +c/2 = 1.66+10.42 = 12.08km - again, insignificantly greater than in yours, and for the majority of location/destinations it will simply be easier to skip the drive altogether and cycle or walk.   

       Allowing a generous 200 meter wide road reserve for the ring road, the entire city occupies a mere 38.85 sq km. Yours takes up 113.10 sq km of land to accommodate the same built area.   

       In short, your flawed reasoning is deeply flawed. I regret that I have but one [-] to give.
BunsenHoneydew, Nov 27 2010
  


 

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