Minding the 2% rule: The best ways to measure sidewalk cross slopes

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Question: What is the "official" way to measure a cross slope on a sidewalk to ensure it complies with the ADA’s 2% or less rule? Should this 2% be measured over the entire width (from the back of the walk to the face of the walk)? Also, should the 2% be measured at 1-foot segments or at 2-foot segments of the sidewalk cross slope? — Scott, Tennessee

Answer: Scott, a great question. My answer is twofold:
  • It is best to measure from the back of the walk to the face. Since the most recent Public Right of Way Accessibility Guidelines (PROW) require a 4-foot-wide sidewalk, I suggest using a 4-foot-long ruler or at least a 36-inch-long digital measurement ruler as your measuring tool.
  • There are no specific guidelines as to using 1-foot segments versus 2-foot segments. However, the more measurements the better.

Put your digital ruler on wheels

My friend Mike Ross is an engineer in the street maintenance division of the City of Overland Park, Kan. He and his staff developed a simple, wheeled device in which you can insert a digital ruler and then roll the device along the sidewalk for readings without constantly bending over and picking up the ruler and putting it down again. It is important to advance a short distance and then stop so an accurate reading is possible. The actual digital readout, of course, faces the person pushing the device.

This tool will also help with measuring the slope of curb ramps, linear slopes of ramps, trail slopes, etc. Most digital rulers also allow you to remove the actual measuring tool in the middle of the ruler to measure small areas.

You can easily make your own version of this tool. When I was working on another project with engineering firm HDR Inc. in Kansas City, Mo., my HDR colleagues saw the tool and were inspired to create their own. If you inspect the pictures of both the Overland Park Public Works and HDR tools included in this article, you’ll see that the way the ruler is inserted is slightly different, but both do a wonderful job.

Mike was kind enough to give me one and I use it all the time.

Take care and best wishes to each of you trying to do your best to improve the world we use and to fulfill the lives of everyone!











This digital survey ruler was placed on wheels by City of Overland Park, Kan., Public Works Department employees.

















After seeing how Overland Park’s device worked, HDR Inc. employees made their own rolling measurement tool.



Comments (4 Total)

  • Posted by: Anonymous | Time: 6:51 PM Thursday, January 14, 2016

    The post on Dec 20, 2013 needs to be answered. 2.1% and some people say "the law doesn't allow us to leave it". What is the allowable error in the equipment?

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  • Posted by: Anonymous | Time: 11:53 AM Friday, December 20, 2013

    I agree easiest is not always best. What do Cities do then? How does your city measure this cross-slope? What if your digital level says the slope 2.1 - do you rip out concrete? What is your slope is 1.9% from front to back of the sidewalk, but clearly the sidewalk has been "bellied-out" in the middle? Lots of issues here....

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  • Posted by: Anonymous | Time: 1:28 PM Tuesday, December 17, 2013

    Needs improved . Not accurate . Easiest is not always best .

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  • Posted by: Anonymous | Time: 8:59 AM Thursday, December 12, 2013

    Digital "level", not ruler.

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About the Blogger

Michele Ohmes

thumbnail image Michele S. Ohmes is an Americans with Disabilities Act specialist and wheelchair user who works with public works departments, facility managers, and contractors. Her design manual — ADA and Accessibility: Let's Get Practical — is available on CD-ROM through the American Public Works Association's Web site. Author's note: Michele & Associates does not render legal advice and has no enforcement authority regarding the ADA or other federal disability-rights legislation.