Cross Slope

[Phil B]

I have a sloping section of walkway that can be easily achieved in under 5%. Its wide enough for 2 way traffic but not really wide enough for people to transverse diagonally. My question is at what width of running slope does cross slope click in? The cross slope on this would be over the allowable 2%. Thanks!

 

[steveray]

I don't think cross slope has anything to do with traversing diagonally.....It's slope perpendicular to the direction of normal travel I would say....

 

[Yankee Chronicler]

There is no width for cross slope to "click in." The slope is the incline in the direction of travel, and the cross-slope is the slope perpendicular to the direction of travel. Cross-slope on an accessible route is limited to 1:48.

 

[Phil B]

There is no width for cross slope to "click in." The slope is the incline in the direction of travel, and the cross-slope is the slope perpendicular to the direction of travel. Cross-slope on an accessible route is limited to 1:48.

I'm talking about a situation where the primary path of travel is as shown below in green where the running slope is 5%, and the cross slope perpendicular to the green path is 0% . As a sloped space gets wider, and it's possible to traverse across the space like shown by the red arrow, the cross slope exceeds 2%. This wouldn't happen if this space was only 5' wide.

 

[steveray]

403.3​

The running slope of walking surfaces shall not be steeper than 1:20. The cross slope of a walking surface shall not be steeper than 1:48.

Don't measure it diagonally...

 

[Phil B]

403.3​

The running slope of walking surfaces shall not be steeper than 1:20. The cross slope of a walking surface shall not be steeper than 1:48.

Yes, I know. My question is that in the 1st sketch I posted, the running slope is under 5% but the cross slope could exceed 2%. Even though traversing at an angle to the running slope probably wouldn't happen because the pathway is narrow, would it be compliant? In the 2nd sketch, the space is wider where traversing across the main path is possible and the space clearly would not be compliant.

 

[steveray]

It’s compliant…you don’t measure diagonally

 

[Yankee Chronicler]

How about posting the actual site plan? If there is an actual direction of travel -- in other words, if this is a sidewalk rather than a terrace or patio where people might be walking in any direction -- then cross slope is measured perpendicular to the direction of travel. Just because someone can walk transverse to a sidewalk doesn't mean the code requires you to treat the cross-slope direction as a second path of travel.

As you have it shown in your second sketch, there is no cross-slope.

In your original sketch, at the top the cross-slope is 1" in 8'-6", or 1:112. That's less than 1%, and since there's no cross-slope at the foot of the walk, the cross-slope will gradually decrease from just under 1% to zero%.

 

[Yikes]

In California, our CBC explicitly describes cross-slope as:

Cross Slope​

The slope that is perpendicular to the direction of travel.

In the image below, if you were traveling in the direction of the green arrows (aka "running slope"), the cross-slope would be the direction of the blue arrows:

 

[Yankee Chronicler]

In California, our CBC explicitly describes cross-slope as:

Cross Slope​

The slope that is perpendicular to the direction of travel.

The same definition is found in the 2010 ADAS and in A117.1

 

[Yikes]

The same definition is found in the 2010 ADAS and in A117.1

Good to know. In CA they italicized it, which typically means a modification of the model ADA language:

 

[Jean Tessmer-HI]

I have a sloping section of walkway that can be easily achieved in under 5%. Its wide enough for 2 way traffic but not really wide enough for people to transverse diagonally. My question is at what width of running slope does cross slope click in? The cross slope on this would be over the allowable 2%. Thanks!

View attachment 15576

Hi Phil,
Here is what the 2010 ADA says.
"Advisory 405.3 Cross Slope. Cross slope is the slope of the surface perpendicular to the direction of travel. Cross slope is measured the same way as slope is measured (i.e., the rise over the run).
Phil, you need to measure the cross slope perpendicular to the direction of the path of travel. If the cross slope is greater than 1:48 or 2.1% it will not be in compliance with the ADA. I am assuming your up arrow is the direction of travel. I am showing that 8" divided by 19' = 3.5% running slope. The 8'6" with 1" difference in height is 0.09% nearly flat. I don't see what the elevations are on the edges of the 5'6" end so can't comment. By the way the recommended sample rate distance is each 24" running slope continuously and each 24" across for cross slope.

 

[steveray]

And here I was thinking it was an angry slope this whole time…I guess a better way to look at it is you are giving them a slope they can navigate properly or safely. If they move across the downslope, that is on them…

 

[Phil B]

Hi Phil,
Here is what the 2010 ADA says.
"Advisory 405.3 Cross Slope. Cross slope is the slope of the surface perpendicular to the direction of travel. Cross slope is measured the same way as slope is measured (i.e., the rise over the run).
Phil, you need to measure the cross slope perpendicular to the direction of the path of travel. If the cross slope is greater than 1:48 or 2.1% it will not be in compliance with the ADA. I am assuming your up arrow is the direction of travel. I am showing that 8" divided by 19' = 3.5% running slope. The 8'6" with 1" difference in height is 0.09% nearly flat. I don't see what the elevations are on the edges of the 5'6" end so can't comment. By the way the recommended sample rate distance is each 24" running slope continuously and each 24" across for cross slope.

What I am guarding against with respect to cross slopes is the situation where I have a large area at the top of sloping walkways leading to the access points of a building as sketched below.
Folks entering and exiting the building can walk in any direction in this area (highlighted in yellow) and therefore I believe all this area needs to be 2% max in any direction. Thank you all for your input!

 

[steveray]

What I am guarding against with respect to cross slopes is the situation where I have a large area at the top of sloping walkways leading to the access points of a building as sketched below.
Folks entering and exiting the building can walk in any direction in this area (highlighted in yellow) and therefore I believe all this area needs to be 2% max in any direction. Thank you all for your input!
View attachment 15588

I CAN walk on the grass...I won't enforce slope on it....