Topic: Driveway angle or pitch.

[CAB]

Is there a "rule of thumb" for maximum pitch for a driveway?
Here in Florida it doesn't come up often. You get a lot where the
elevation rises sharply from the street and too quick a rise in the
driveway and some cars scrape the tail pipe on the street when
you pull into the driveway.  
I have not been able to find any "regulations" regarding this subject.

Thanks in advance.

CAB

[Keith™]

Well Cab, tell the contractor to do a straight slope of no greater than street level to garage level.... that should get them thinking...

[CAB]

Keith,

That would work in most cases given the setback requirements.
The problem with lots that have a sharp rise from th street is
that a gently sloping driveway will cut into the rise and create
banks on each side of the driveway. You would then have to grade
those sides to avoid a retaining wall. The GC chose to put the
driveway in at the given slope and the new owners car scrapes
when pulling into the driveway. This was a friend of a friend who
bought a house in a development near where i live. So my friend
was telling me about it and I wanted to make sure it never happen
to one of my projects. Thought i would start my search here knowing
there are house designers & civil people here that may have
encountered the problem.

CAB

[Keith™]

Oh... well you can fix a heap of problems with a little bit of site work. Forget the retaining wall, grade the banks down to provide a sloped effect to the drive.
OR
Just tell them to park in the street.

[hendie]

couldn't they just have the exhaust pointing out the front of the car   or blow up their tyres higher ?

[Kate M]

OR just build it like this:

[daron]

Good luck to that company selling any houses. I wouldn't buy there. What's worse, the driveways from the road don't match up with the runways from the house. You need an SUV just to get in the garage.

[Mark]

The one on the end would be fun to back into the garage! Although, I bet Se7en could do it!

[CAB]

What did they, do use gunnite and shoot the driveways.

I've never seen concrete poured at that slope?

An SUV must come with the house as a purchase insensitive.

Great picture Kate.

CAB

[daron]

Probably precast and laid in place.

[Bob Garner]

Yes, CAB, there are rules of thumb for the amount of angular change between the street and the driveway to prevent cars from scraping.  I believe these are in Architectural Graphic Standards.  I got a heck of a lot of work to do right now, but when I get a chance, I'll try to look this up for you.  When the angle is too much, you can put in a sag vertical curve to make a more gentle transition, although that will require a steeper driveway.  That said, I will ask our survey forum members to whip up a parabolic curve equation to help you out.

Kate, that photo is cool.

Bob G.

[Mark]

>I've never seen concrete poured at that slope?
It can be done provided the slump of the conc. is tight enough.

[CAB]

Thanks Bob,
I would like to see the guideline when you have time.

CAB

[Bob Garner]

Hi, CAB

Page 39, 6th Edition of Architectural Graphic Standards (kinda out of date) says the angle of departure (which is a line drawn from the center of the rear tire contact patch to the lowest part of the rear of the car, the exhaust pipe), should be no greater than 10 degrees for a 1968 Mercury.  This is the maximum angle between the street and the driveway.  Some cities regulate this and you may find the maximum allowed angle of departure from the building or zoning department.  Or you could check some car specs.  Again, you can use a greater angle if you use a vertical curve but this forces a steeper pitch in the driveway.

My experience with maximum driveway pitches is 10% prefered, 20% if you have to.  And remember, to figure what angle this is, you gotta remember that a 100% pitch is 45 degrees.  Some of the streets in San Francisco exceed 20%.

Hope this helps.

Bob G.

[CAB]

Thanks so much for the info.

CAB

[rugaroo]

CAB,

Here in vegas, the max driveway slope is 12%. Grwanted this does not include the slope of the sidewalk (2%) or the 5' landing in front of the garage door (also 2 %). Maybe that will help some.

[CarlB]

CAB,
This question has been discussed a few times at eng-tips, although you guys have hit on the main points. One thread is at http://www.eng-tips.com/viewthread.cfm?SQID=72147&SPID=158&newpid=158&page=1

[CAB]

Thanks for the info rug.

Carl, the site is down so I'll try again later.

I"ve been there many times but not lately.


CAB

[Martin-Y]

On the ramp to an undergroud car park we designed a few years back we used transition curves at the top and bottom of the ramp. The slope was 16.6% or approx. 1 in 6 and the radius of the arc for the transition curve was 15m. This suited our european size cars but may not be enough for the leviathans you guys drive!!

[CAB]

Martin,

leviathans

Thats great..
I drive a one ton dually myself.

I think the transition curves you mentioned is the way to go.

I did find more info on driveways, see the link to pdf file.

http://www.theswamp.org/lilly.pond/CAB/Res%20DrivewayDeltona.pdf

[pmvliet]

kate,
where is that photo from? Is it a real driveway?

I actually saw another photo, different view of the same driveway

Pieter

[Kate M]

Pieter,

I got it (and two others, maybe one of them is the same as yours) from a friend of mine, who got it from a co-worker, who got it from...I also got it from my boss, under different file names... I think they've just been floating around.

[pmvliet]

That's about the story on this end as well.
We were debating if it was indeed a true driveway that was built
and not photo-edited to look that way.
Some people are very creative with photoshop type programs
and it is hard to tell sometimes...

[CarlB]

Yes, those are real pictures.  I got a confirmation from the design group involved, out of Ventura, California.  I don't think they would want me to give their name.  The designer's defense was it was the developer's fault.... They told us they didn't care what it took ( I think the quote was "even if we need to build a funicular") the earthwork had to balance.

[daron]

California huh? Is the name DMB? We've bought a nightmare of a piece of land recently that has alley loading back-of-house driveway/garages. The driveways aren't so bad, but the land was developed in such a way the at about halfway down the lot, the land drops straight down or up 2'. That's a nightmare to design for.