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Thread: Maximum residential driveway slope?

  1. #26
    Cyburbian
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    Oops! I used those pictures a couple years ago when the issue of max. driveway slope was at issue. Contractors said there was no need to put a max. grade into the code. I showed them the pictures and we settled on 17% with an administrative review for something greater. We were proposing 12%. My own driveway is +20% and occasionally during the winter, I can't get up it. Couple winters ago, a neighbor knocked on my door to tell me my car slid into the street.

  2. #27
    Super Moderator luckless pedestrian's avatar
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    our requirement:

    Driveways shall not have a grade in excess of 15% over the entire length. On arterials, the grade shall not be more than 5% for the first 25 feet from the road unless otherwise approved by the Planning Board. Driveways shall not be located where visibility is limited because of curves or topography.
    I would prefer it to be closer to 10% or 12% might be okay but 15% has caused an oil truck and an ambulance to tip over in icy conditions so if it's a wintry locale, then I would go less than 15%...

  3. #28
    Cyburbia Administrator Dan's avatar
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    I found a few more photos of the infamous Fayetteville driveway, before the relocation of the sidewalk.









    I think the two most commonly seen photos that are seen online made their way from email lore to the wider Internet when they appeared on Cyburbia in 2003.

    A few more from flickr:

    http://www.flickr.com/photos/ask3y/2684673761/


    http://www.flickr.com/photos/53074154@N00/992237649/


    Growth for growth's sake is the ideology of the cancer cell. -- Edward Abbey

  4. #29
    Cyburbian fringe's avatar
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    I don't have pics but maybe one day...

    I saw one almost this bad inspecting for the county, so steep that I would not park the county truck on it, and if you did go all the way up to the snout garage it scraped the underside of the vehicle.

    Incidentally another inspector signed off in error on the building's distance from the edge of a descending slope (it was too close) on one side adjacent to the steep front.

    The house, built on spec, has been sitting for 2+ years, the builder went bust and handed 70-80 houses back to the bank in our county alone. With its proximity to the edge of the slope and rainfall way above normal the last half-year I would not be surprised to see the house begin to go south.

  5. #30
    Gunfighter Mastiff's avatar
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    You'd have to know Fayetteville to understand. I worked for the firm that designed the subdivisions east of this place, and I'm fairly certain the same developer owned this piece of land. The city probably was a hard case about the planting strip out front... until they saw the result.

    If you're curious as to why they didn't level the lots down to match the street elevation more closely (you can see there is no reason why you couldn't), it's because taking the fill to some off-site location costs bucks. Part of the blame is on the engineer for not doing better cut/fill calcs and raising the street elevation while lowering the lot, and the developer is a dolt (and if it's who I think... he is...) for not using the situation to his advantage and cutting the garage into the side of the hill.
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  6. #31
    Cyburbian
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    Quote Originally posted by Mastiff View post
    You'd have to know Fayetteville to understand. I worked for the firm that designed the subdivisions east of this place, and I'm fairly certain the same developer owned this piece of land. The city probably was a hard case about the planting strip out front... until they saw the result.

    If you're curious as to why they didn't level the lots down to match the street elevation more closely (you can see there is no reason why you couldn't), it's because taking the fill to some off-site location costs bucks. Part of the blame is on the engineer for not doing better cut/fill calcs and raising the street elevation while lowering the lot, and the developer is a dolt (and if it's who I think... he is...) for not using the situation to his advantage and cutting the garage into the side of the hill.
    Sometimes this sort of thing is also about managing the client's expectations. If you set it up from the beginning that the land needs cut/fill, and some of the cut material needs removal/disposal, then the engineer doesn't get into a jam trying to make the developer and the city "happy" with conflicting needs/requirements.

    I'm sure many a good engineer has pulled his or her last hair out trying to resolve that conflict.

    But in the meantime, what, they don't SELL cut material to willing buyers out there in Fayetteville, or better yet - give it away for free if you bring your shovel, wheelbarrow and truck (or whatever apparatus you have that will move it) ...??

  7. #32
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by Mastiff View post
    The city probably was a hard case about the planting strip out front... until they saw the result.
    If this is true, that's pretty sad -- there's no sidewalk on the other side of the same street but they're fixated on regulating the amount of planting strip here?

    The end result of a reduced parkway and lesser slope shows a good solution, it's just too bad that all the time and materials was wasted in the process of first building it.

  8. #33
    Gunfighter Mastiff's avatar
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    Quote Originally posted by Gatrgal93 View post
    Sometimes this sort of thing is also about managing the client's expectations. If you set it up from the beginning that the land needs cut/fill, and some of the cut material needs removal/disposal, then the engineer doesn't get into a jam trying to make the developer and the city "happy" with conflicting needs/requirements.

    I'm sure many a good engineer has pulled his or her last hair out trying to resolve that conflict.
    I'm not sure that in the 10-12 years I worked designing subdivisions that I've ever seen a client interested about the vertical curves or elevations on a street or the slope of a sewer line. If they like the layout, and assume they can sell the lots, it's all good. I mean, this isn't even a particularly hilly area of the town...

    Quote Originally posted by Gatrgal93 View post
    But in the meantime, what, they don't SELL cut material to willing buyers out there in Fayetteville, or better yet - give it away for free if you bring your shovel, wheelbarrow and truck (or whatever apparatus you have that will move it) ...??
    Well, yes and no... You can find people who will take clean fill, but having them come and get it is a bit harder, especially if you have a lot of it. Add to that having someone else in the way during construction, and sometimes it isn't worth the trouble.

    Quote Originally posted by UrbaneSprawler View post
    If this is true, that's pretty sad -- there's no sidewalk on the other side of the same street but they're fixated on regulating the amount of planting strip here?

    The end result of a reduced parkway and lesser slope shows a good solution, it's just too bad that all the time and materials was wasted in the process of first building it.
    Well, I don't know it for a fact... I just knew how they could be at times. What looks good in plan view doesn't always work so well in the field.
    Last edited by Mastiff; 20 Jan 2010 at 3:34 AM.
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  9. #34
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    I've seen driveways sloped up to 25% in the Atlanta, Georgia area. Doesn't seem they'd be safe even with rain water, let alone ice and or snow.
    They should at least require a concrete surface finish compliant with DOT road standards, which is a heavy, raked concrete surface, perpendicular to the line of travel.
    Even then, I think I'd stay home on cloudy days.

  10. #35
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    They can't be serious!

    Those photos must be fakes. I can't believe that the Fire Dept of where ever that is would sign off on that.

  11. #36
    Cyburbian UrbaneSprawler's avatar
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    Would a Fire Dept. have concerns? I'd assume they would just setup and stage on the street where the hydrant is closer. They'd have no reason to drive their trucks on these driveways and I imagine would probably crush the concrete if they did. If a normal person can walk from the street to the front door, why not a firefighter? The distance from the street to the front door seems fine in all the cases for hose to reach.

    Paramedics might find bringing a stretcher in/out challenging. But we don't have ambulance services as a regulatory review with our building permits. I suspect ambulance services typically aren't reviewing authorities?

  12. #37
    I stumbled across this while doing some research for my own lot in north GA. I looked up the address in Google Maps and looked at the street view. It looks like they moved the sidewalk closer to the street to enable a (slightly) better angle for these homes. Still pretty steep though. I'm trying to figure out how to get an acceptable driveway on a lot that has an average 43% grade.

    http://maps.google.com/maps?oe=UTF-8...22.82,,0,17.19

  13. #38
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    math says max slope is

    I did calculation assuming garage slab drops 3" over 24'. The question is how much can driveway slope without bottom of car scraping. Assuming car has wheelbase of 102" and minimum clearance underneath to ground is 5", the max slope the driveway can be is 20%.

  14. #39
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    Great Find Sinjin5!

    I agree with Dan, these pictures are real. Look at the lawn width between the road and the sidewalk in the construction photos and the asBuilts on StreetView. Much narrower in the final product.

    I expect that the subdivision regs or some county designer demanded this much clear zone between the roadway and th sidewalk, leaving insufficient space for the driveway. I'm sure the contractor took these pics after pouring all that nice concrete, sent it to the county design engineer and BCC'd it to the world. This is a little tame for threrifixedit.com, but along the same lines.

    Having just one mission usually gets the job done faster than those of us who think about the bigger picture, but this always results in a mess someplace else. This one is just more obvious.

  15. #40
    Those are teh steepest freakin driveways I have ever seen!

  16. #41
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    Why would someone slightly scrunch the photographs horizontally, since the original aspect ratio is dramatic enough? I know this for a fact - I'm the one who took the photographs. There is no digital altering of any sort other than these posted photos being a little too narrow. Although that was several years ago, 2003 maybe?, I've just now stumbled across this very interesting thread.

    I was City Engineer for Fayetteville at the time, and was stunned to see such a ridiculous driveway being constructed. The white car in the photo, our department vehicle, does look a little too narrow in these posted photos. Of course, the Mayor and all sorts of people were immediately notified of this insane situation, and I sent several photos out to disbelieving friends. I'm guessing that's how they ended up on the internet, and were even seen in a military presentation in Korea!

    ESI out of Springdale was the site engineer, and Riggins Construction was the developer and homebuilder. We called them immediately to try to find some sort of after-the-fact solution, which you eagle-eyed folks have spotted. The best we could come up, short of demolishing the houses and rebuilding with 2-stories, was to move the sidewalk closer to the street and then tear out and repour the driveways. It didn't gain them much, but I suppose every degree counts in this instance.

    At the time, Fayetteville did not have any maximum driveway slope regulations - so much for assuming common sense would prevail! I always thought the market would keep these houses unsold for years, but they sold shortly after being completed - I would have loved to see them struggling to move in.

    I will try to locate the original photos and post them. To paraphrase, "no planning or construction mistake is totally useless, it can always be a bad example!"

    Gary

  17. #42
    Cyburbian Random Traffic Guy's avatar
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    Thanks for the update and welcome to Cyburbia!! I always like to hear the details behind some of the crazy things we see.

  18. #43
    Cyburbian UrbaneSprawler's avatar
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    Yes, thanks for the further insight!

    I'm curious to know if Fayetteville had/has a requirement of some sort of plot plan/improvement location drawing that calls out foundation elevations, slopes, etc. reviewed by the municipality prior to building permit issuance? If so, were the houses built to a plot plan that called out the driveway slopes on paper, or perhaps was there a deviation in the field elevating the foundations with the result of increasing the driveway slopes beyond what a plot plan called for?

  19. #44
    Cyburbian
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    some cities don't have a choice, do a lack of flat or even easily gradable land. San Diego's statutory maximum is 20% I think, but if it's greater than 10% then you have to minimum 8' transitions at a maximum of a 6% grade at the top and bottom.

    So basically you need to have a flat or nearly flat run of 8', angle up at 20% and then flatten out for another 8' run before the garage or building entrance.
    Last edited by Cismontane; 01 Jul 2010 at 9:05 PM. Reason: adding more info

  20. #45
    Cyburbian jswanek's avatar
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    .

    For something really awful, start with the worst slope, say 28%. Then you need 8 foot long transitions at the top and bottom of 18%, followed by ADDITIONAL 8 foot transitions of 9%. So you have the dreadful middle section, with 24 feet total of transitions.

    We require a use permit for anything over 20%, with findings of public safety. With an aging population, I have real problems with a LONG steep driveway that neither a fire truck or an ambulance would even attempt.

    If it's a relatively short (80 feet?) super-steep driveway, fire-fighters and ambulance attendants can climb stairs and even finagle a stretcher up and down the stairs, but I can't see how you could make safety findings for ANYTHING over 30%.

    But a long steep driveway means someday a member of the household or a guest will have a heart attack and just die there.

    .

    .

  21. #46
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    MAX DRIVEWAY GRADE

    LOL - Our policy has same photo! The policy we use requires maximum 12% driveway grade; however, the real key is that to provide less steep "transitions" at top and toe to prevent cars from scraping.

  22. #47
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    Fayetteville Driveway

    I have tracked down one of the original photos of the infamous Fayetteville driveway, but can't figure out how to post it. I'd be happy to email it to anyone - I can be reached at gcoover at swbell dot net.

    G

  23. #48
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    sidewalk is moved

    Quote Originally posted by UrbaneSprawler View post
    True, I shouldn't assume what exactly happened. A plot plan could have been prepared and reviewed and the contractor set the foundation higher than the drawings.

    But, it seems to me that before the driveways were poured and then torn out, someone between the inspector and the contractor should have decided an alternative on paper? There's no sidewalks on the other side of the street (apparently it's not really valued there).

    They could have eliminated, attached, or as they finally did reduced the detachment of the sidewalk before grading and then pouring the driveways "just to see". What a waste.
    Looking at the Google picture you can see where the sidewalk further up and down the street is farther from the street. Is definately pushed to the road for these three lots.

  24. #49
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    Fayetteville - driveways

    I contacted the City of Fayetteville and confirmed that the driveways were relocated closer to the road to reduce the slope.

  25. #50
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    Quote Originally posted by Gatrgal93 View post
    Or maybe the picture was "squished" on the horizontal axis? I was looking at the cars and they look more narrow than they should. Or maybe I need glasses at this point?
    The photos were horizontally "squished" to make the driveways seem more steep. As evidence, consider the ratio of height to width of the streetlight on the corner. In these doctored photos, that ratio is somewhat narrower than in the Google Streetview photos of the same streetlight closeup. The side view from Streetview also shows a less steep driveway than these two photos pretend.

    This thread caught my eye because many years ago in the 1990s I also doctored one of these photos (or more likely the original) and posted it on the web. I too wanted to make the driveway seem comically steep. Using Photoshop, I squished the photo and also cut the middle house and moved it to the left while steepening the driveway. It overlapped the far house with the hip roof more than in the original. I've since misplaced my digital copy, and can't recall where I posted it on the web. I must have spent an hour to get the trees (that were then overlapping) to look right. In my photo alteration, the driveway was about this steep but the houses were more believable and less squished, even though the perspective vanishing point of imaginary lines drawn along their eaves didn't converge perfectly. What fun we Photoshop users can have with gullible web viewers!

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