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Thread: Maximum residential driveway slope?

  1. #1

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    Maximum residential driveway slope?

    Looking for the answer to this -- what's the maximum driveway slope permitted in your area? Our design guidelines call for a maximum driveway slope of 10% for standard residential driveways, but an applicant is seeking something along the lines of 20%... One concern about a steep driveway is the vehicle bottoming out and scraping the ground where the grade changes from angled to flat. Another would be the driveway being too steep to negociate in the winter.

    We also call for the slope from the PL to the street to slope downwards towards the street at no more than 2%, which is part of the problem in this case.

    I don't have much experience in the field of driveways... so what's your experience with steep residential driveway grades? How steep can they be?
    Last edited by DPP; 19 Jul 2006 at 6:23 PM.

  2. #2
    Cyburbian Otis's avatar
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    Our maximum is 15%. We are in a hilly area, for what that is worth. Most of the easily buildable lots in town are developed or not available, so builders are turning to the more challenging lots. It makes for some interesting proposals.

  3. #3
    Cyburbian
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    Does the drive cross a sidewalk? Maximum crosslope on a SW is 2%.
    Most towns around here have an 8% to 10% max slope, but we are naturally flat.

  4. #4
    NIMBY asshatterer Plus Richmond Jake's avatar
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    Probably not this steep (courtesy of Tranplanner):




  5. #5
    Cyburbian Random Traffic Guy's avatar
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    Damn, beat me to the pictures of what not to do.

    Perhaps it is a chance to teach the builder a lesson? LOL, as long as you've got somebody strong to tell any possible buyers that it isn't the city's problem.
    Or say 20% is okay but convince him to turn it into a 4x4 themed development? He could probably save money by not grading or paving roads, etc.

    Seriously...
    My parking manuals show 20% is "considered" for ramps within parking structures in hilly areas. But 15%+ give some drivers problems, and 12.5% is about the limit for comfortable walking. If you're parking a car on it, about 7% is the max...

    For transitions, if it is greater than 6% difference in grade, there should be a short vertical curve (10' length) used instead of a single break point. But this in turn makes the sloping area shorter and thus steeper.

  6. #6
    Cyburbian
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    What's the grade on those drives? Looks like about a 15 foot drop in about 25 feet. That's 60%.
    If they put the garage at basement level, it would be about right.
    Last edited by noottamevas; 19 Jul 2006 at 9:34 PM.

  7. #7
         
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    Man, didn't anyone review those plans? Anyone know if those houses ever sold? I suppose someone without a car might get one cheap...

  8. #8
    Cyburbian Emeritus Chet's avatar
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    15%??!! Good god. We recently changed our codes in one community to limit public streets to 10% and driveways to 4% to preserve topography. Anything else requires a conditonal use.

  9. #9
    Cyburbian Random Traffic Guy's avatar
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    Those pics are supposedly real, but suspiciously I've heard they are from either Arkansas or Austin TX. Lax reviews, slapdash contractor...

  10. #10
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    15% is the most I would realistically go, and only if the area dictates it necessary. If not, I like 10%. Also really depends on if your house is front entry or side entry.

    If side, there are tricks to get the house up higher in the air (swithback drives, pitch on the driveway pad, garage under the house, etc).

  11. #11
    Super Moderator luckless pedestrian's avatar
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    we require 15% over the entire length of the driveway and 5% at the entrance to the street - this is way too steep and must be changed -

    in the winter, this island gets alot of ice, more than snow and we always lose an oil truck that tips over trying to deliver oil -

    we are also getting calls from insurance companies that ask our Fire Department if he can get a truck/ambulance up there ad when they are steep like this, he nows says "no I can't" and these people have a hard time getting insurance, especially the second home buyer which we have a lot of...

  12. #12
    Cyburbian UrbaneSprawler's avatar
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    verified to be real?

    Bumping this old thread because I've always been curious to know if these pics are real or doctored and perhaps someone knows for sure?

    When I first saw these pics emailed around, the file name for one of the pics was 5028NewBridgeRd. (The EXIF data on the pic shows it was apparently taken on 11/12/2003 with a Nikon Camera). Interestingly, "5028 New Bridge Road" doesn't show up as an address using Google.

    I've just can't believe the image is real; what municipality would allow this? Now with Google street view, perhaps someone can confirm or disprove it?

    Quote Originally posted by RichmondJake View post
    Probably not this steep (courtesy of Tranplanner):




  13. #13
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    Found the neighborhood on Google Street View like you suggested. 5028 New Bridge Road, Fayetteville, AR 72704. The pictures were indeed doctored...

  14. #14
    Unfrozen Caveman Planner mendelman's avatar
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    I don't know. The neighborhood you cite doesn't necessarily look similar (ie buildings), and I still have trouble seeing how the pictures were doctored. Everything the images seems to naturally connect to everything else - the edges of the driveway pavement and the dirt piles intersect seamlessly and the shading is consistent - but there may be a phenomenal photoshopper out there somewhere.

    Here's a photo that looks from the same development:
    steep driveway slope
    I'm sorry. Is my bias showing?

    Let's not be didactic in this profession, because that is a path to disillusion and irrelevancy.

    Six seasons and a movie!

  15. #15
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by Sinjin5 View post
    Found the neighborhood on Google Street View like you suggested. 5028 New Bridge Road, Fayetteville, AR 72704. The pictures were indeed doctored...
    THANK YOU! I've always wondered about this for years and you found the location (here's a google street view link). You rock!

    It is a fraud. It's steep no doubt, but not that steep.

    http://maps.google.com/maps?f=q&sour...12,358.77,,0,5

  16. #16
    Unfrozen Caveman Planner mendelman's avatar
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    Nevermind. And good find.
    I'm sorry. Is my bias showing?

    Let's not be didactic in this profession, because that is a path to disillusion and irrelevancy.

    Six seasons and a movie!

  17. #17
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by mendelman View post
    but there may be a phenomenal photoshopper out there somewhere.
    No doubt, it can't be lost that there's a brilliant photoshopper out there that needs to take credit (not blame) for this. I've seen these photos presented in conferences before. Next time I'll yell out "fake".

  18. #18
    Cyburbia Administrator Dan's avatar
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    The photos are real, but ...

    Mystery solved, I think.

    Current Google Street view.

    Same house as the infamous original photo: note the gables over the garage and the neighboring house. Note the sidewalk is much closer to the street than the original photo, with a much narrower tree lawn.

    Now, turn around. In this Streetview scene, the sidewalk curves back from the street, resulting in a deeper tree lawn, with about the same depth of what's seen in the original photos.

    My conclusion: the sidewalk was relocated further from the houses and closer to the street, and the driveways rebuilt to decrease the slope somewhat. The photos in this thread are real, but do not reflect the current improvements and grading on the site. The driveways are still very steep, but not as bad as when they were first built.
    Growth for growth's sake is the ideology of the cancer cell. -- Edward Abbey

  19. #19
    Unfrozen Caveman Planner mendelman's avatar
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    Good sleuthing Dan. This makes it even better - it can be a classic case of allowing for field changes and how plans may not always work once construction begins.
    Last edited by mendelman; 15 Jan 2010 at 11:02 AM.
    I'm sorry. Is my bias showing?

    Let's not be didactic in this profession, because that is a path to disillusion and irrelevancy.

    Six seasons and a movie!

  20. #20
    Cyburbian
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    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?

    UPDATE: okay, I looked again ... I think you're right Dan. The sidewalk is way closer in the google streetview than in the original pics. Squishing the picture wouldn't have created that effect; however it does sort of look like someone squished the picture a little bit and it might have exaggerated the original built condition a hair.
    Last edited by Gatrgal93; 15 Jan 2010 at 10:59 AM. Reason: upon second glance ...

  21. #21
    Cyburbian UrbaneSprawler's avatar
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    Quote Originally posted by Dan View post
    My conclusion: the sidewalk was relocated, and the driveways rebuilt. The photo is real, but does not reflect current improvements. The driveways are still very steep, but not as bad as when they were originally built.
    Ah, I see that now. Great call.

    My faith in humanity was restored moments ago and now it's lost again. How Fayetteville, AR would have allowed a building permit to have been originally pulled and built is beyond me.

  22. #22
    Cyburbian
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    If everyone thinks those driveways (current form not pre-stabilization) are steep I should share some picture of driveways in my hood.

  23. #23
    Quote Originally posted by UrbaneSprawler View post
    Ah, I see that now. Great call.

    My faith in humanity was restored moments ago and now it's lost again. How Fayetteville, AR would have allowed a building permit to have been originally pulled and built is beyond me.
    What's shown on a plan set for a permit and what's actually built in the field can be two entirely different things. That's why we inspect project sites.

  24. #24
    Cyburbian
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    Quote Originally posted by UrbaneSprawler View post
    Ah, I see that now. Great call.

    My faith in humanity was restored moments ago and now it's lost again. How Fayetteville, AR would have allowed a building permit to have been originally pulled and built is beyond me.
    Contractors screw up at times. I wouldn't necessarily blame the permitting entity. It could easily have been a misread on the approved plans, the inspector looked at it, got a good laugh and said, no, boys, try again. I'm sure the construction foreman wasn't laughing, of course.

  25. #25
    Cyburbian UrbaneSprawler's avatar
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    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.

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