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Thread: Debunking the cul-de-sac

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    Cyburbian Veloise's avatar
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    Debunking the cul-de-sac


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    Cyburbian ColoGI's avatar
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    Quote Originally posted by Veloise View post
    Good link, thank you. Perfect for the layperson, IMHO.

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    Cyburbian Raf's avatar
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    Quote Originally posted by ColoGI View post
    Good link, thank you. Perfect for the layperson, IMHO.
    It was a great read. I tweeted it for my fellow non-planners. Nothing really new to add to the discussion that hasn't been brought up before, except maybe costs associated with curve linear streets and additional asphalt/concrete on a per LF level.
    follow me on the twitter @rcplans

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    Cyburbian
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    I didn't find it particularly useful as a "Debunking" the myth of the cul-de-sac.

    I imagine most residents of cul-de-sacs would read the article, blink, shrug and promptly forget about it.

    In other words, it's just preaching to the choir of people who'd never live on a suburban cul-de-sac.

  5. #5
    Cyburbian ColoGI's avatar
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    Quote Originally posted by PennPlanner View post
    I didn't find it particularly useful as a "Debunking" the myth of the cul-de-sac.

    I imagine most residents of cul-de-sacs would read the article, blink, shrug and promptly forget about it.

    In other words, it's just preaching to the choir of people who'd never live on a suburban cul-de-sac.
    It depends on scale and which Overton window you want to look through.

    If you are a planner permitting a new development and the public asks you why you aren't permitting culs-de-sac, you can give them a photocopy of this article, telling them that traffic is an issue in the community and that is why we don't install culs-de-sac. If a good, patriotic family simply has to have a house on one, maybe there is one somewhere else for them.

  6. #6
    Cyburbian
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    Good luck with that response in most suburban jurisdictions.

    We can always debate the pros and cons of cul de sacs but the article only rehashes points made for some time - indeed I remember them from graduate school eight years ago.

    In general, I didn't find anything in the article that would convincingly persuade the public to accept a ban on new cul de sacs. Actually, in a lot of older suburbs where infill is the only form of development, cul de sacs are often the only choice for plotting out the few acres left between existing developments.

    Blaming cul de sacs is really missing the point - the problem is strict euclidean zoning and segregation of land usage and the sprawling nature of developments that encourages dependencies on driving. None of the problems are going to disappear without cul de sacs, as the existence of plenty of older suburban developments with few or no cul de sacs but which are still car dependent can tell you.

    Quote Originally posted by ColoGI View post
    It depends on scale and which Overton window you want to look through.

    If you are a planner permitting a new development and the public asks you why you aren't permitting culs-de-sac, you can give them a photocopy of this article, telling them that traffic is an issue in the community and that is why we don't install culs-de-sac. If a good, patriotic family simply has to have a house on one, maybe there is one somewhere else for them.

  7. #7
    Cyburbian DetroitPlanner's avatar
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    Good points Penn. The cul-de-sac is just the tip of the iceberg. Being raised in the City I never understood why folks in the burbs would want to make it so hard to walk from one land use to another.
    We hope for better things; it will arise from the ashes - Fr Gabriel Richard 1805

  8. #8
    Cyburbian ColoGI's avatar
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    Quote Originally posted by PennPlanner View post
    Good luck with that response in most suburban jurisdictions.

    We can always debate the pros and cons of cul de sacs but the article only rehashes points made for some time - indeed I remember them from graduate school eight years ago.

    In general, I didn't find anything in the article that would convincingly persuade the public to accept a ban on new cul de sacs. Actually, in a lot of older suburbs where infill is the only form of development, cul de sacs are often the only choice for plotting out the few acres left between existing developments.

    Blaming cul de sacs is really missing the point - the problem is strict euclidean zoning and segregation of land usage and the sprawling nature of developments that encourages dependencies on driving. None of the problems are going to disappear without cul de sacs, as the existence of plenty of older suburban developments with few or no cul de sacs but which are still car dependent can tell you.
    You should try explaining what culs de sac do. You might be surprised. My publics get it, but maybe you live somewhere where they don't care.

    At any rate, no one is 'blaming' culs de sac for all the world's ills. I think we all know about Euclidean zoning, but you have to start somewhere. Thanks!

  9. #9
    Cyburbian
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    Explain cul de sacs?

    Sure. They've been used in American land development for over a hundred years now. Olmsted pioneered the use of cul de sacs in his designs.

    The home buying public likes cul de sacs as they're perceived to be quieter with no through traffic. Quite often they're popular places for children to play and ride bikes on in suburban areas due to the lack of traffic. Houses on cul de sacs generally command a premium over the same house not on a cul de sac.

    in hilly areas cul de sacs actually allow a more efficient form of platting versus a standard grid. Cul de sacs are also useful in infill developments when linking up to an existing street network isn't possible.

    If you're genuinely concerned about walkability, plan for sidewalks. Lots of sidewalks and pathways, which can easily go through the dead end of a cul de sac. Changing the road typology doesn't mean much.

    At the end of the day, it is just a street. Banning it isn't going to change anything.

    Quote Originally posted by ColoGI View post
    You should try explaining what culs de sac do. You might be surprised. My publics get it, but maybe you live somewhere where they don't care.

    At any rate, no one is 'blaming' culs de sac for all the world's ills. I think we all know about Euclidean zoning, but you have to start somewhere. Thanks!

  10. #10
    Chairman of the bored Maister's avatar
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    Every design has its own advantages and disadvantages, and PP pretty well identifies the advantages of cul-de-sacs. Concerning the issue of 'walkability', though, I would add that simply providing sidewalks in and of itself really doesn't promote or encourage their use. The question is where do the sidewalks lead to? In the large majority of suburban cul-de-sacs (see conventional post-1950 design from the article below) the answer is yet another residential street.



    Useful maybe for an evening stroll through the subdivision or taking the dog on a walk, but little more.

  11. #11
    Cyburbian Tarf's avatar
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    Quote Originally posted by Maister View post


    Useful maybe for an evening stroll through the subdivision or taking the dog on a walk, but little more.

    Don't disagree, but to some extent what you're pointing out is not problems with cul-de-sacs per se, but the overall design of a community.

    In the image of the "Conventional Cul-De-Sac" above, the block shown in the lower right appears to have several cul-de-sacs backing up on a paseo/greenbelt - thereby providing pedestrian pathways that are totally separated from traffic. I support this concept.

    The problem is that the greenbelt doesn't go anywhere. (Also, the remaining cul-de-sacs shown do not front on paseos/greenbelts, and are definitely poorly designed).

    Cul-de-sacs aren't necessarily "evil." They're just designed that way (danged engineers!).
    In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move. (Douglas Adams)

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    Cyburbian ColoGI's avatar
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    Quote Originally posted by tarf12345678 View post
    Don't disagree, but to some extent what you're pointing out is not problems with cul-de-sacs per se, but the overall design of a community.

    Cul-de-sacs aren't necessarily "evil." They're just designed that way (danged engineers!).
    Exactly so. As we emerge (hopefully) from auto-dependence and return to earlier community design to inform modern design, we find that culs-de-sac impede connectivity.

    This is a question of scale: who do you design for? The atomistic unit or a larger community/region? Thus the Overton window I wrote of upthread.

    It is what it is. There are tradeoffs. Cramming 8 houses on a vacant lot may lead to only one choice: a cul-de-sac. No one is arguing for banning that.

  13. #13
    Cyburbian Streck's avatar
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    You must see the plan for Lake Vista in New Orleans:

    http://http://maps.google.com/maps?q...ed=0CCkQ8gEwAQ

    This is a Google Maps link. You may have to zoom in. It is best seen with both streets and satellite images.

    The site is on the lake shore and contains many cul-de-sacs with walking and bike trails to a central shopping area with church and school.

    It was designed in 1938 and interupted during WWII, but all houses were sold immediately after the war.

    It is a wonderful up-scale place to live.
    Last edited by Streck; 06 Oct 2011 at 10:35 PM. Reason: Added recommendation to view streets and satellite image.

  14. #14
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by tarf12345678 View post
    The problem is that the greenbelt doesn't go anywhere. (Also, the remaining cul-de-sacs shown do not front on paseos/greenbelts, and are definitely poorly designed).

    Cul-de-sacs aren't necessarily "evil." They're just designed that way (danged engineers!).
    What exactly did us engineers do wrong regarding the cul-de-sac? Last I recall, us engineers merely implement the site layout done by the land planner with the greenbelt that doesn't go anywhere.

  15. #15
    Cyburbian
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    In general, I didn't find anything in the article that would convincingly persuade the public to accept a ban on new cul de sacs.
    In my experience, the public at large couldn't care less unless you're messing with THIER already existing cul-de-sac. Its more decision-makers (including some developers who've always done cul-de-sacs) who need convincing - and could be swayed by well-reasoned arguments around traffic and fiscal responsibility. We need transportation egineers and emergency responders to the supporters of connectivity (saw some great presentations at CNU in Denver, with emergency responders endorsing). I think where planners fail is where they make arguments that are based on urban aesthetic, which then become arguments of what I like vs. what you like. While I don't know the details, VA banned cul-de-sacs statewide, based on the fact that the state maintains and plows all roads, right?

    All in all, I wonder if we should be arguing for connectivity, rather than against one symptom of poor connectivity (the ill-used cul-de-sac). If there's a cul-de-sac or two thrown in because a site ended up laying out that way, or becayse of topography, I'd think that's OK as long as a measurable level of connectivity is acheived.

    Most designers today are being trained in the pseudo-new-urbanism so in the future it may be a moot point? Pseudo-new-urbanism becomes the new conventional, and covention trumps reasoned debate most of the time, right?

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    Cyburbian mike gurnee's avatar
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    In a former town there was a cul-de-sac with 10 nice middle class homes occupied by nice middle class families who enjoyed their short, dead end street. After ten or so years of living in their little enclave they were shocked, SHOCKED to learn the the developer had retained ownership of the last lot. And he built a new street into a new subdivision off of that lot. AND he made it a connecting street.

  17. #17
    Cyburbian Streck's avatar
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    Quote Originally posted by Streck View post
    You must see the plan for Lake Vista in New Orleans:

    http://maps.google.com/maps?q=lake+v...ed=0CCkQ8gEwAQ
    I discovered that the link had a double "http" entry, and I was unable to get to the site.

    Hopefully this corrects the link.

    Yes, this does it.

    Note that even though cul-de-sacs prevent "thru-traffic" (as they are intended), this "block" of cul-de-sac development is surrounded by four lane through-traffic streets, and traffic moves well around it - as intended.
    Last edited by Streck; 14 Oct 2011 at 8:13 PM. Reason: Added the last two sentences after checking the changed link address.

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    Cyburbian Tarf's avatar
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    Quote Originally posted by UrbaneSprawler View post
    What exactly did us engineers do wrong regarding the cul-de-sac? Last I recall, us engineers merely implement the site layout done by the land planner with the greenbelt that doesn't go anywhere.
    Tongue in cheek comment (for the most part).

    However, I will say that some of the most egregious examples of cul-de-sacs I've seen have been TMs that were designed by engineers from basic land use plans (i.e., just a designation, no street design).

    I've also seen some pretty poor designs from (other) planning firms... like, bad enough that we had to do a re-design to fix it. (We've also fixed many an engineer's design).

    As with planning, engineers are "good" or "bad." I would assume that an engineer that takes the time to read a planner's forum site is probably better than one that doesn't
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  19. #19
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by Tarf View post
    However, I will say that some of the most egregious examples of cul-de-sacs I've seen have been TMs that were designed by engineers from basic land use plans (i.e., just a designation, no street design).
    If an engineering drawing just indicates a cul-de-sac street with no horizontal and vertical design information, that's reporting to the state board material I would think. I'd be putting it back on the engineer to do a suitable design before approving the development.

    From my perspective as an engineer, cul-de-sac's tend to be more problematic from an implementation and maintenance perspective than through streets. Since our local fire department has required cul-de-sacs to be 100 feet in diameter, getting water to drain across asphalt at a distance of 50 feet (or more), while at the same time ensuring the water is conveyed around the cul-de-sac in the gutter section is often a balancing act. Also if the drainage from the street goes towards the bulb rather than away from it, there's an inlet to add to an area that already has something like six pie-shaped lots, plus an access ramp. Finding room for all that in the bulb itself (and when the lots are viewed as premium with folks then wanting 3 car garages), is a pain.

    I'll take grid street design review over cul-de-sacs any day.

  20. #20
    Cyburbian Streck's avatar
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    Quote Originally posted by Tarf View post
    The problem is that the greenbelt doesn't go anywhere.
    Tarf was referring to some of the other designs above, but notice that the Lake Vista "greenbelts" created between the cul-de-sac streets are linked to the central area which included a small grocery store, a church, and a school.

    Notice also that the cul-de-sac neighborhood is also linked to a major walking/riding parkway all along Lake Pontchartrain. There are many open areas for picnicing and ball fields. There are occasional picnic shelters and some have toilet facilities. It extends to the marina and yacht club to the west and all the way to a small general airport on the east (if you would ever want to go that far).

    The western lakefront parkway also also extends southward along a bayou to a small shopping center with a movie theater.

    Directly south of the Lake Vista subdivision is City Park.

    Cul-de-sac neighborhoods could also provide passageways to other neighborhoods, larger neighborhood parks, or schools without crossing major streets.

  21. #21
    Cyburbian Streck's avatar
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    I would like to add one other thing that you can see in Tarf's third image, in that the informal cul-de-sac layout also provides an opportunity to preserve drainageways and creek beds and larger stream beds in their natural landfall so that flooding is minimized and contained in its natural terrain configuration with a minimum of regrading and loss of trees and natural habitat.

    This is a mark of good sensitive planning.

    It is also less expensive than having to construct major culverts to cross under so many streets as in the grid plan.

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