# Don't Get Disabled by ADA Requirements for Sidewalk Cross-Slopes



## mark handler (Jun 27, 2011)

Don't Get Disabled by ADA Requirements for Sidewalk Cross-Slopes

Posted: June 23rd, 2011 12:43 PM CDT

  By Ward R. Malisch, P.E. and Bruce A. Suprenant, P.E

http://www.forconstructionpros.com/publication/article.jsp?pubId=7&id=20676&pageNum=3

Almost every concrete contractor has a horror story about trying to build sidewalks that meet the requirements of the Americans with Disabilities Act (ADA). One of the most costly problems is meeting requirements for maximum slope because there is no plus tolerance for the maximum cross-slope of 2 percent. Because of this maximum limit, a measured cross-slope of 2.05 percent almost always results in contractors being forced to remove and replace sidewalk sections at their expense.

Because of the need for drainage, a typical sidewalk design might call for a minimum cross-slope of 1.5 percent in addition to the ADA-required maximum of 2 percent. At present it isn't clear whether sidewalks can be built within these limits. In addition to this constructability question, there are two major problems:

Cross-slopes greater than the 2 percent maximum are not necessarily a hazard to the disabled, and There is no standardized method for measuring cross-slope, thus making enforcement measures extremely arbitrary, as will be discussed.

Origins of the 2 percent maximum slope

Was there any research and science used to set the 2 percent maximum -- research based on the stability properties of various wheelchairs, scooters, walkers, or crutches and on the physical condition of the disabled user? Apparently not.

One group of researchers stated the following:

On the basis of a review of scientific literature on cross-slope design, the conclusion must be drawn that prior research is insufficient to support the ADA 2 percent cross-slope requirement.

Through the course of this research, the exact history of this 2 percent cross-slope requirement could not be ascertained, and no research and science supporting a unilateral 2 percent requirement was found.

Results from the most relevant existing reported work, conducted using plywood ramps, can be interpreted to indicate a maximum "short distance" cross-slope in the neighborhood of 16 to 20 percent. For somewhat longer distances, a reliable upper bound may be closer to 10 percent. When they are considered with the various constraints, these results support the idea that the ADA 2 percent limit might be too strict for relatively infrequent short-distance sidewalk sections such as driveway crossings.(1)

Given that the 2 percent maximum cross-slope is an arbitrarily chosen number, what is the correct maximum slope? Research results from the University of Texas at Austin provide evidence that a 4 percent maximum cross-slope may accommodate the largest number of possible disabled users.(2) The conclusion from this is that rejecting a sidewalk with a cross-slope slightly greater than 2 percent is gross overkill. But because the U.S. Department of Justice enforces the 2 percent slope, cities, states and private builders must all meet this onerous standard.

Measurement disorder

There is a lack of guidance in ADAAG regarding distances over which to take cross-slope measurements in the field. Inspectors have used any instrument from a 6-inch-long spirit level to an ultra-light inertial profiler equipped with a gyroscope that, by averaging, can estimate the cross-slope over a width of 5 feet or more.(3) The 2-foot-long Smart Tool™ is commonly used for measurements.

Regardless of the tool used, there is no standardized test method for making cross-slope measurements. Any number of measurements may be taken in any area of the sidewalk, and with no rules for averaging measurements, discarding outliers or treating the data in a standardized manner. Thus, two inspectors from the same agency and using the same tool can record different cross-slopes for a given sidewalk. If one of the readings exceeds 2 percent, it's likely that one will be used and require corrective action.

Problem solutions

Based on the points presented here, three recommendations are as follows:

•ADAAG should change its requirements so that the maximum sidewalk cross-slope is 3 percent and the minimum slope is 1.5 percent. Based on the research cited, the 3 percent maximum is reasonable.

•The designer can then set a target value of 2.25 percent with a ±0.75 percent tolerance which would reduce the constructability challenge.

•Develop a standard method for measuring cross-slope, disseminate it to all agencies or testing firms charged with verifying compliance with ADA requirements and indicate that no action can be taken unless the standard measurement method has been used.

Until such steps are taken, contractors will continue to be unjustly penalized by the absence of reality-based requirements and arbitrary measurement methods.

References 1. Kockelman et al, "Sidewalk Cross-Slope Requirements of the Americans with Disabilities Act: Literature Review." Transportation Research Record No. 1705, Journal of the Transportation Research Board, pp. 53-60, Dec. 2000.

2. Kockelman et al, "Meeting the intent of ADA in sidewalk cross-slope design," Journal of Rehabilitation Research and Development, Vol. 38, No. 1, January/February 2001, Pages 101-110.

3. City of Bellvue, Washington, "Americans with Disabilities Act (ADA) Sidewalk & Curb Ramp Inventory," Case Study, National Cooperative Highway Research Program (NCHRP), Asset Management Approaches to ADA Compliance, NCHRP 20-07 Task 249.

Ward R. Malisch, P.E., is technical director for the American Society of Concrete Contractors. He can be reached at wmalisch@ascconline.org. Bruce A. Suprenant, P.E., is the president of Concrete Engineering Services. He can be reached at bsuprenant@concretees.com. This column is sponsored by the American Society of Concrete Contractors, but the views expressed are solely those of the authors.


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## Inspector Gift (Jun 27, 2011)

Mark, thanks for your post.  (This is a hot topic currently in my small jurisdiction.)


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## mtlogcabin (Jun 27, 2011)

"Construction tolerances" are also not normally accepted within the accessibility guidelines as pointed out by the article. The link below is a well written arcticle on construction tolerances.

http://www.access-board.gov/research/tolerances/design.htm


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## Frank (Jun 28, 2011)

These cross slope issues are a major PITA for all involved.

If I got 10 cents a pound for all the concrete and asphalt that gets torn out before it is 60 days old due to slope issues I could have retired a long time ago.

Consider also that for sidewalks adjacent to buildings there is a building code required minimum slope away from the building of 2%  2009 IBC 1804.3

Compare that to the maximum 1:48 ICC ANSI A117.1-2003 cross slope (2.08%)

This gives an allowable slope range of 2 to 2.08% a variation of just over 1/32 of an inch in 48 inches--This would be considered ultra flat for concrete floors pushing the limits .

Add to this the normal settlement of the backfill that will impact the slopes--note that the ADA case may come years later.  Had one complaint about an accessible parking place that I could see the settlement of a poorly compacted ditch in the aerial photograph on GIS--slope has to be bad to be able to reject it from the office.  In this particular case the 2 ft wide ditch across the parking places had settled 2 to 5 inches.

As cross slope increases it becomes more difficult to keep a wheelchair going straight requiring additional effort on the user or pusher to keep it from turning downhill potentailly involving falling off the curb or into traffic.

Given the Accessibility driven 2% max cross slope with potential 3rd party federal court enforcement and the above drainage driven 2 % minimum slope away from the building we have decided that for accessible routes adjacent to buildings that are not under roof to enforce a 1.5 % minimum cross slope for drainage.

Note that these are minimum and maximum slopes at any one point--not averages although given the 1/4 inch abrupt level change and the 1/2 inch wide slot dimension arguments can be made for a 1 ft minimum averaging distance.

Our typical field measurement of slopes is done with a 4 ft level and a tape measure or stick rule.

1 inch of fall equals the 1:48 A117.1 maximum cross slope.

Given that few are good enough to read level bubbles and a rule that close, due to measurement uncertainty our rejection points are 1/2 and 1-1/4 inches in the 48 inch level for sidewalks ajacent to buildings and 1-1/4 inch in 48 for other cross slopes, landings and parking places. For landings and parking places we find the slope by finding level direction and then turning the level 90 degrees.  A caveat--our passing it with a slight excess in slope will NOT protect you from the feds or the lawyers and their pet clients.


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## Papio Bldg Dept (Jun 28, 2011)

mtlogcabin said:
			
		

> "Construction tolerances" are also not normally accepted within the accessibility guidelines as pointed out by the article. The link below is a well written arcticle on construction tolerances.http://www.access-board.gov/research/tolerances/design.htm


It seems to me that Ward and Bruce could benefit from spending a little more time actually reading the access board's articles, as well as directly contacting the access-board hot-line for guidance, as this AHJ has.  Spending some time navigating in a manual wheelchair on slopes in excess of 2.5% might be educational as well.  My recommendation is that they try crosswalks at busy intersections, espcially where motorists do not typically stop at the marked cross walk, as well as residential drive-ways (typically at 8%) that do not change slope at sidewalk crossing.  A majority of the designs I see, set all of thier standards at the maximums, in this case 2% (and we wonder why there are non-compliance issues when designers don't factor in a construction tolerance when a maximum is given by a compliance standard), while most of the contractors simply place a 6' level on a form stake (3/4" thickness) on the opposite form of a 4' sidewalk for a 1.56% cross slope.  Must be listed under the 'rocket science' section on 'forconstructionpros' website.

In addition, I think Frank makes a valid arguement about the 2009 code changes.  I will definitely consider a similar amendment.  Is there a distance away from the building at which point 1804.3 for minimum slope does not apply?


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## Frank (Jun 29, 2011)

The technical provisions are the same in the 2006 IBC 1803.3.  The minimum 2% slope for impervious surfaces applies for the first 10 feet from the building.

I wish the state had ammended, but these are our informal guidlines to the inspectors in that the difference between to much and too little cross slope (1/32" in 4 ft) is beyond our measurement capabilities with a 4 ft level and a rule.  In tests with different people taking repeated measurments of same slope variation was on the order of a 3/8" range so if it over 1/4" off we have a high confidence it is an actual violation not a measurment error.  Note that we do not measure all cross slopes or parking spaces, just the ones that don't look or feel right.


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