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Does ramp slope include cross slope?

Y

Yikes

SAWHORSE
Joined
Nov 2, 2009
Messages
3,967
Location
Southern California
Picture this: an exterior walkway, 10' long and 4' wide.

The forward slope on the walkway is 4.9%, which is less than 5%, so no "ramp" designation and no handrails, right?

But wait, the cross slope is 2% for drainage runoff. That means if someone went diagonally from the highest corner to the lowest corner, the actual slope would be about 5.7%.

Is it now considered a ramp? Or do you never measure slope on the diagonal, that is, never include the cross-slope (and thus the walkway is considered only 4.9%)?
 
Re: Does ramp slope include cross slope?

IBC (2006) Section 1010 makes a distinction between running slope and cross slope. I believe if you have a running slope of 4.9 and a cross slope of 2, you would be in compliance.
 
Re: Does ramp slope include cross slope?

If the forward slope is 4.9% and the cross slope is 2%, and someone traveled from the high top corner on one side and then ended up on the bottom low corner on the other side, they will not have negotiated a 6.9% slope. If you were to place your "smart level" on the ramp in the direction of travel as mentioned above (diagonally from upper high side to lower bottom side), the slope would probably not even reach 5% (or it would be close to 5% anyway).
 
Re: Does ramp slope include cross slope?

5.29% on the diagonal.

You'll have to provide landings on the diagonal too with this line of reasoning.

The handrails...they'll be a mess.
 
Re: Does ramp slope include cross slope?

I do not see anywhere that we are to combine these slopes. Use a 6" smart level and you might be just be over 4.9% :lol:

1003.5 Elevation change. Where changes in elevation of less than 12 inches (305 mm) exist in the means of egress, sloped surfaces shall be used. Where the slope is greater than one unit vertical in 20 units horizontal (5-percent slope), ramps complying with Section 1010 shall be used. Where the difference in elevation is 6 inches (152 mm) or less, the ramp shall be equipped with either handrails or floor finish materials that contrast with adjacent floor finish materials.

1010.2 Slope. Ramps used as part of a means of egress shall have a running slope not steeper than one unit vertical in 12 units horizontal (8-percent slope). The slope of other pedestrian ramps shall not be steeper than one unit vertical in eight units horizontal (12.5-percent slope).

1010.3 Cross slope. The slope measured perpendicular to the direction of travel of a ramp shall not be steeper than one unit vertical in 48 units horizontal (2-percent slope).

1010.7 Ramp construction. All ramps shall be built of materials consistent with the types permitted for the type of construction of the building, except that wood handrails shall be permitted for all types of construction. Ramps used as an exit shall conform to the applicable requirements of Sections 1020.1 through 1020.1.3 for exit enclosures.

1010.7.1 Ramp surface. The surface of ramps shall be of slip-resistant materials that are securely attached.

1010.7.2 Outdoor conditions. Outdoor ramps and outdoor approaches to ramps shall be designed so that water will not accumulate on walking surfaces.

1010.8 Handrails. Ramps with a rise greater than 6 inches (152 mm) shall have handrails on both sides. Handrails shall comply with Section 1012.
 
Re: Does ramp slope include cross slope?

I agree with Dave; you don't combine.

Uncle Bob
 
Re: Does ramp slope include cross slope?

Oh, you are all so darned agreeable!

The requirement is that the slope in the "direction of travel" and its cross slope must be controlled. If movement in the diagonal is possible, that's nice. But is it the "direction of travel" or not?

We recently found out that public sidewalks are a major source of trouble on sloped sites since they need landings at all the doors to allow for turning and access to the door entry. Although the public sidewalks are Title II - not Title III - and the providence of the local AHJ, they can create problems for building access. However, the Access Board and its public R.O.W. committee both agreed that if there is movement parallel to the building/street that is within the proper slope/cross slope proportions, then the only thing that was critical was that there was a landing at changes in direction (where the slope in any direction did not exceed 2% in any direction).

In other words, if you don't need to turn, don't assume someone will.
 
Re: Does ramp slope include cross slope?

OK, here's another real-world example - a small, multilevel parking garage, with accessible stalls on the ground level. Each double-loaded parking drive aisle (about 25' wide) on the upper deck of the garage is a continuous 4.9% slope, with a 2% cross-slope to direct any water/snow runoof from the cars towards a central drain/curb.

So, for the typical person parking their car on the upper decks, they will get out of their car, walk down the middle of the drive aisle, until they reach the exit stairs or elevator. This is their exit path-of-travel.

QUESTION: With a 2% cross-slope on a 25' wide space, is this parking deck now considered a "ramp"? If so, then will the design require a dedicated sidewalk in front of the cars (extra 4' width per row), just to keep the occupants from exiting in a partial cross-slope direction that exceeds 5%?
 
Re: Does ramp slope include cross slope?

Thank goodness that the accessible stalls are on the ground level!

I'd never consider that a ramp - although I still can't figure out why those parking garage engineers want to use such steep slopes when a 3 or 4 percent slope does every bit as god as a 5 percent slope at shedding water.
 
Re: Does ramp slope include cross slope?

Gene - I agree that it is not preferred to have parking stalls on a 4.9% slope - even apart from the code limits, you don't want car doors banging into each other.

I live in an area where most development is infill, and in my real-world example the lot size was very short, pushing the parking slope to its limits in order that the second deck level could get high enough over the ground level to permit 8'-2" headroom for the van accessible stalls on the first level.
 
Re: Does ramp slope include cross slope?

Yikes,

If the slope is from one side to the other that's one thing. It's the garages that look like waffles or roller coasters that get me - up to the ridge, then down to the catch basin, up to the next ridge. . . . . . :mrgreen:
 
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