Advantages and Disadvantages of Circular Roads

Factual Questions
21

Rochester, NY, is another city built on radials converging on downtown. Except that they never got around to building the circles. So it’s completely impossible to move across the radials. You have to move on one straight street and then cut over to another straight street and then try to find a bridge across the river that bisects the city. This makes public transportation a joke unless you want to go downtown.

That may be one reason I started studying urban design seriously. I can’t think of many serious city plans that use circles. The only thing that comes close is that there was a vogue in the 1960s to plan circular freeways to route traffic. That’s why so many cities have an “inner loop” or “inner belt” and an “outer loop” or “outer belt.” This seems to work.* But once you get off the belts and onto “surface” streets, you need a grid pattern to get around properly. It just gets harder and harder to get around a circular pattern because every major street gets farther and farther apart as you move away from downtown.

  • Work for auto traffic. They’re terrible for cities. To create an inner freeway belt in an existing city requires tearing down the oldest neighborhoods in town. You could do this during the urban renewal days of the 50s and 60s but it’s incredibly destructive to the city fabric. And since traffic can only cross freeways at a few points they form separate sections with no connections. And cities absolutely require connections between neighborhoods.
22

Buildings don’t have to be square.

Subdivision of land doesn’t seem like a very big problem - most new housing developments here in the UK seem to have road layouts that look like a dither pattern, but they manage to slice the plots up OK.

Grids are inconvenient for people travelling diagonally and radial layouts are inconvenient for people travelling from any point within the circle to points about a quarter to a points around about a third of a turn from themselves. There must be some way of optimising it so as not to construct too many roads, but at the same time, shorten and simplify journies

23

I’m not sure how this works. Why are connections necessary? And if they are, why is it impossible to build a connection over a freeway? Living in Calgary (near Glenmore Trail, a freeway, where it meets MacLeod Trail, a major arterial surface road {link}), I actually found it much easier to cross the freeway (due to bridges) than cross the arterial road. Why can’t bridges link communities across a freeway?

24

I know that… but this was in response to the previous poster… however reading his comment again, I grant that he was talking about lots not buildings. My bad.

25

This is pretty much the default for cities which start small, and grow slowly and organically. The radial roads converge in a small area because they were originally routes to that place, and not through a large urban area. As the city grows and the space between the radial roads is built up, circular roads appear; they are sometimes but not always the result of intentional urban planning, unlike the radial routes, which “just growed”.

Navigation is a pain, at least for strangers, unless you are headed to the city centre, in which case it’s a doddle. It’s a particular pain for strangers who come from grid cities and are accustomed to navigating by street junctions. This simply doesn’t work. The locals are unlikely to do this; if they are trying to tell you where to find a particular address on one of the longer routes, they’ll name the district it’s in, rather than the junction it’s near (unless it happens to be near a junction with a very prominent road). And, in fact, in Dublin, where I grew up, even the few prominent junctions that are used for navigation are not named after the streets that intersect there, but after landmarks like pubs, or other features (Doyle’s Corner, Kelly’s Corner, the Big Tree, the Five Lamps).

Well, in so far as this is the result of a city growing organically, it has the positives that any organic system has. It has grown as a response to the conditions that the people actually experienced, not as a response to somebody’s idea of what people wanted or ought to want.

It may or may not be connected, but the European stereotype of American cities is that (with a few prominent exceptions) they tend to be a bit characterless, and the more gridlike cities tend to be more characterless. There is more to the quality of life of any city than being able to drive through it quickly, or to have others drive through it quickly, Streets need first and foremost to serve the community that use them – those who live, work or recreate in the properties on or off those streets, those who want to get to or from those properties, on foot or by car or other transport. Getting people through the neighbourhood on their way between two other places is a secondary consideration.

26

No offense to you, but this reminds me of why I curse the name of the Marquis de Lafayette every time I have the misfortune of driving in DC. (It’s well-known that the Marquis designed the city for maximum driving misery, having first designed Hell as a warm-up.)

I’m a fat, stupid* American. Give me a nice Cartesian grid.

*Which is why I believe that Lafayette designed DC.

27

As mentioned, washington DC has a lot of circles with radial connection, and it also has a rectangular grid. While the circles must have seemed like a great idea in the horse and buggy days, and the early decades of the auto, they have evolved into bizarre concatenations of double circles, traffic lights, and underpasses to allow traffic to flow smoothly, and I find it a hassle both to walk through as a pedestrian or to drive through. Add to that the fact that a lot of Americans really don’t know (or care) how to drive properly in traffic circles, and you have the makings of traffic jams.

As for Rochester, it has an Inner Interstate Circle and an Outer Interstate Circle (just like Boston, in fact), but it’s got grids, too (only they often don’t cross at right angles, which is weird). I fdon’t get the feeling at all that it is built on concentric circles, or on a cradial plan. It’s got a few radial routes, but so do all cities.

(Boston doesn’t have a lot of p;lanning, and the older areas are simply insane. Then they threw in a lot of bitty traffic circles, apparently just to be ornery.)

28

But you’d never get the type of city layout the OP is talking about ‘organically’. You mention Dublin, and someone else mentioned Vienna - while those cities do have a couple of ring roads going around them, if you look at the map both of them are just mishmashes of streets going everywhere, like most European cities, which does give them more character.

What the OP is talking about though is a city designed from scratch, perfectly organized into a series of ring roads radiating outwards from a central point with a series of arterial routes crossing them. That design would be no less characterless than the American grid-style cities.

29

I’d disagree with that. In both Washington and Canberra, part of what gives the city its character is the avenues and circles that break the grid pattern. They make it hard to navigate the city, especially in a car, but they also give those cities the grand vistas that make them look so wonderful. It would be harder to do that with a rectangular grid.

30

Vienna has the Ringstrasse for weird historic reasons. The city originally was literally a fortress, with high walls first built by the Romans, then rebuilt by Leopold II in 1200 and then a two-mile in circumference fortress with 11 bastions facing onto a moat and glacis (an open, cleared area) by the Hapsburgs in the 16th century.

By the 19th century the ancient barriers were totally obsolete. The inner city was the home of the rich and titled, but was so small that they had to build up rather than out, a pain in the days before elevators. And there were 400,000 people in the half square mile inner city, a density worse than New York’s Lower East Side slums.

Emperor Franz Joseph finally tore down the walls and built the circular Ringstrasse to replace that along with the open areas. Modern apartments and the major buildings of a modern city (an Open House, City Hall, Museum, etc.) were built.

But the Ringstrasse compares to an inner loop. The rest of the city does not have a circular structure.

Rochester is all radials. St. Paul, N. Clinton, Joseph, Hudson, North, Portland, Goodman, East Main, East, University, Park, Monroe, S. Clinton, South, Mt. Hope, State/Plymouth, West Main, West, Lyell, Lake. All radiate out from the Inner Loop. There are some grids between them but all get cut off sooner rather than later.

The idea once was to create a major ring system of scenic Boulevards. That’s where St. Paul Boulevard, Mt Read Boulevard, Genesee Park Boulevard and the couple of others come from. But they were never connected. So you get things like Clifford and Emerson in a straight line with no bridge connecting them. The bridge is at Driving Park, but that’s a block over from Avenue D, the natural connector. Ridge Road does make a loop to the north and Elmwood/Genesee Park Boul. to the south but those are too far out for city traffic. The only east/west street in the whole city that works as one expects is Main St. And idiots keep talking about closing part of it to cars.

Because isolation is death to cities. In older cities, neighborhoods are too small to support services like high schools, supermarkets, libraries, fire stations, or other basics of city life. They need to pool together to make up sufficient populations. You may have found an exception but 99.9% of the time a freeway is an impassible barrier. Places with barriers get cut off and deprived of services and street life.

31

There are exceptions. One is the National Mall in Washington DC, between 2nd Street (NW and SW) and 3rd Street (NW and SW): Interstate 395 goes under there, but you can’t see it, since it’s in a tunnel. Another is High Street North in Columbus OH, where it goes over Interstate 670. There are shops and restaurants built on both sides of the bridge, so you can’t see the interstate from High Street, and the neighbourhoods north and south of the bridge are linked.

But I agree that the exceptions are rare, partly because they are more expensive than an ordinary road bridge to build.

32

I have lived in the DC area for 25 years. I like traffic circles in general and have found them very beneficial in Europe. But in DC they are abominations. Dupont Circle is the worst. The image doesn’t do it justice–it has a two-lane inner loop that allows Mass Ave traffic to go straight through and a two-lane outer loop that must be coordinated with the inner loop, not to mention dozens of traffic lights. I thought the point of circles was to eliminate the lights…

33

I was agreeing with you and extending your point further. A rectilinear grid is only ideal if we demand rectangular divisions - and we simply don’t need to do that.