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Thread: Block sizes, intersection density, and street widths

  1. #1
    Cyburbian
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    How important are these factors to creating a walkable place?

    My intuition tells me that, by far, the biggest reason tighter networks are more appealing to pedestrians is the fact that the crosswalks are shorter and that, if crossing these streets was simply made more comfortable through means that do not necessarily include road diets and new mid-block streets, any pattern would be walkable enough to work.

    Minimizing walking distances and providing a variety of routes are, ultimately, not nearly as significant as simply removing the awkward feeling pedestrians have at most crossing places.

    I suppose I should distinguish intersection density from crosswalk density and/or the presence of woonerfs, which I believe are both important. Chamfered corners also probably help relieve the relentlessness of a pattern with large blocks.
    Last edited by Gedunker; 08 Dec 2010 at 10:48 AM. Reason: seq. posts

  2. #2
    Cyburbian Linda_D's avatar
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    PI, you need to leave SoCal and come up to Jamestown, NY where you can experience first hand a real "impediment" to "walkability": 5 straight days of lake effect snow yielding 2-3 feet of snow on the ground, a relentless 20-25 mph wind gusting to 30 creating 4 foot drifts, and windchills in the single digits or lower. I had to snow blow a path through the drifts in my backyard so my 15-year-old dog could have a place to poop.

    Believe me, living in a tough climate will make you appreciate the automobile in ways you never would think it possible, especially those vehicles with AWD.

  3. #3
    Cyburbian DetroitPlanner's avatar
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    Places like Manhatten are considered very walkable yet have very long blocks.

    If you lived further east you would experience things known as Arcades that have been developed to shrink the walking distances and create pedestrian passages in long blocks. Cleveland has several, other citires with them include Buffalo, Nashville, Ann Arbor, and several along the eastern seaboard.

    If you are looking for some magic formula to block size and street width good luck.
    We hope for better things; it will arise from the ashes - Fr Gabriel Richard 1805

  4. #4
    Cyburbian ursus's avatar
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    Salt Lake's blocks are a standard over 600 feet long. They're huge. However, certain sections of downtown are fairly walkable because alleys and other plazas allow pedestrians through the blocks where automobiles are relegated to that original superstructure of 600 feet, probably much like the arcades that Detroit Planner is describing above. I actually find it to be versatile for planning purposes, and fairly walkable. When we lose the notion that walkable areas have to be shared car/pedestrian access the block sizes are not so important.
    "...I would never try to tick Hink off. He kinda intimidates me. He's quite butch, you know." - Maister

  5. #5
    Cyburbian Raf's avatar
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    Quote Originally posted by ursus View post
    we lose the notion that walkable areas have to be shared car/pedestrian access the block sizes are not so important.
    Agreed. Walakability is something that happens with time. Not an instant oatmeal approach because you threw in a road diet, some midblocks crosswalks and a few starbucks' into the mix. Walkability really comes down to uses that people want to walk to, density available to walk to said location, and the availability of sidewalks to get to point A to point B. You can have a small street with a typical 10 foot lanes with parking and not seem walkable at all because of the uses (or lack thereof) or you can have a huge street, 6 lanes in each direction and be perfectly walkable (i.e. San Francisco's Embcadero).
    follow me on the twitter @rcplans

  6. #6
    Cyburbian
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    Pedestrians always want to take the most direct route, and that makes sense, it takes a lot of personal energy to walk. Cycling is more efficient and therefore cyclists will take a slightly longer detour if necessary. People in cars expend very little personal energy and therefore they will accept much longer detours.

    When designing a pedestrian neighbourhood the walking routes between where people are and where they want to go must be as direct as possible. A grid pattern of streets with short blocks and lots of crosswalk opportunities makes it possible to walk from any one point to any other point as directly as possible. When someone is about to run an errand - how directly they can walk to their destination may be the deciding factor as to which mode they take.

    Street widths are another issue. Streets that are too narrow can mean narrow sidewalks and no landscaping which can make for a hostile pedestrian environment, however streets that are just wide enough are generally preferable to pedestrians because it creates a sense of enclosure and makes crossing the street easier, not only because the distance is shorter, but also because traffic tends to move slower in visually constrained places.

    Alleys, walkways and arcades can add to the pedestrian network, but they must be perceived as being safe.

  7. #7
    Cyburbian cng's avatar
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    Quote Originally posted by Linda_D View post
    PI, you need to leave SoCal and come up to Jamestown, NY where you can experience first hand a real "impediment" to "walkability": 5 straight days of lake effect snow yielding 2-3 feet of snow on the ground, a relentless 20-25 mph wind gusting to 30 creating 4 foot drifts, and windchills in the single digits or lower. I had to snow blow a path through the drifts in my backyard so my 15-year-old dog could have a place to poop.

    Believe me, living in a tough climate will make you appreciate the automobile in ways you never would think it possible, especially those vehicles with AWD.
    Yuck snow... yes, it prevents people from wanting to be outside... I'm going on vacation to Utah and Oregon to visit family for Christmas and hoping not to come across any of that. I am in SoCal, and even here, it can get blazing hot in the desert areas, so similarly, people want to stay indoors and in their vehicles as well. I may still walk on a 100-degree day, but only after I arrive at a certain destination, and not as a means of self transportation.

    I would be more particular as to where I want to encourage pedestrian-friendliness within a city. I think main-street commercial serves a different purpose than service-oriented commercial (auto shops, etc.). For some communities, you'll need your office parks, auto malls, big boxes, and compact block patterns simply won't accommodate these uses.

    On the other hand, I think we can do better with connecting residential homes to schools and parks. We can do better with providing trails through neighborhoods, and providing connections to neighborhood commercial uses. In these context, I would narrow the streets and encourage block patterns with connections. In my city, our residential streets are 40-foot-wide, curb to curb. I think we can narrow this down to 32. Our blocks can extend over 1000 feet. I think they can be half the length.

  8. #8
    People seem to walk and bike in Scandinavia in all season. In Boston, people are out in all types of weather. Sure pedestrian activity drops, but it doesnt go to zero unless there are other things going on.

  9. #9
    Cyburbian
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    There's an obvious trade-off between block sizing for walkability and block sizing for (internalized) quality of life. Portland's tiny 100'x100' downtown blocks and 120'ishx350'ish inner city blocks are great but completely preclude mid-block greenery - if you want green, you have to designate the entire block as green-space. San Diego's 180'x200''s likewise encourages 55-80% block coverages that effectively preclude midblock open spaces. Its 140'x350' configuration - common in mid-city and uptown neighborhoods - similarly limits and precludes mid-block open space. On the other hand Brooklyn's 200'x500'-800's permit some amount of mid-block greenery for residential typologies. Downtown Denver's an interesting one (220'x300') allowing for some interesting typologies but San Francisco's blocks, which are just 20-30' shorter (200'x300') also encourage full-block penetration. I don't understand why 180's-220's encourage full block penetration on the west coast but don't do so on the east coast.

    Don't know what's better.. but there it is...

  10. #10
    Cyburbian ColoGI's avatar
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    Quote Originally posted by DetroitPlanner View post
    If you are looking for some magic formula to block size and street width good luck.
    What he said.

  11. #11
    Cyburbian Linda_D's avatar
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    Quote Originally posted by Howl View post
    Pedestrians always want to take the most direct route, and that makes sense, it takes a lot of personal energy to walk.
    Ever notice the well-worn footpaths on college campuses created by students taking the most direct routes to dorms or classroom buildings? A lot of the time they just cut off square corners of sidewalks but other times they create straight or curved paths across lawn areas. I always wondered why so many college administrators persist in ignoring "natural" travel patterns when planning campus landscaping and paving/sidewalk projects.

  12. #12
    Cyburbian
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    Quote Originally posted by Linda_D View post
    Ever notice the well-worn footpaths on college campuses created by students taking the most direct routes to dorms or classroom buildings? A lot of the time they just cut off square corners of sidewalks but other times they create straight or curved paths across lawn areas. I always wondered why so many college administrators persist in ignoring "natural" travel patterns when planning campus landscaping and paving/sidewalk projects.
    I agree. So many college campuses still have a towers-in-the-park design that completely ignores the sense of enclosure that makes people feel comfortable. Walt Disney, a hero of mine in this regard, was approached soon after Disneyland first opened by the landscape architects who insisted that their planters be encircled by fences in order to prevent people from taking shortcuts, and his response was to, instead, pave the paths these guests were using.

    With a regular street grid, walking distances are not going to improve much by adding additional paths parallel to those that already exist. Radial passages that lead to and from centers or cores, however, do make sense. Disney used the standard of a mile per day to determine the maximum walking requirements the design of Disneyland would impose on guests, and the triangular shape provided significant efficiency by placing the entrance and the exit close to the center of the parking area.

    The circularity of the walkways is also important since so many trips are taken between and among "third places." So, paths and passages that form concentric rings around centers and cores should probably supplement the radial network. Ideally, some synthesis of a largely-orthogonal grid for cars and jitneys and a hub-and-spoke layout for pedestrians and higher-order transit can provide the best of all worlds.

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