Cross slope of driveway

[smokiibear]

Can anyone pitch in on a maximum cross slope of a driveway? I've got a street longitudinal grade of 10 percent over the frontage of a lot of 142' in length. The architect and client are hoping for two driveways that make a u-shape and then connect with the garage. As a result of that 10% grade on the street, I've been trying to get the two driveways to merge properly without a high amount of cross slope. Any recommendations?

 

[Pinwards]

Try to hold 2% cross-slope and make up the grade longitudinally if you can. It sounds like you have pretty challenging terrain for that type of loop driveway, so it may not be possible. At cross slopes of 4-5% it gets difficult to open car doors on the uphill side. Is this in an area that gets any cold weather? That's a steep street.

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[oldestguy]

I'd make sure that at least the entry to the garage is as near to 2% as possible all directions for the likely possibility some day you will have old folks who can't get in or out of the car on steep places. Also those folks might want to enter or leave by foot and may resort to using the car just to get to a mail box (my neighbor). Is the house plan for handi-cap access? That affects outside grades also.

 

[TerryScan]

I concur with the spirit of the feedback thus far.

I can't really read the stationing on the screen grab...but to get from 10% to 2%, I would typically try to make that transition over 145 ft.

 

[civilman72]

I can't tell in your sketch where the garage is located, but regardless, it looks like you are sloping the driveway towards the building. You need a low point away from the building which means your driveway will likely get steeper.

 

[chicopee]

Study the design of the private driveways connected to Lombard street in San Francisco. Lombard street is about 27% in grade. You may get some inspiration from that design.

 

[eea]

Is this new construction? If yes, lower the building pad of the house / garage. As already mentioned this is far from pedestrian or ADA centric. Even better if this is still in the design stage, I think I'd try and flop the footprint of the site and move the driveway to the right side of property closer to the swale. It looks like you could key into Elev 900+/- and set the FF at near the same. The street is in a down gradient from right to left and drops from 905 to 895 across the frontage.