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% of slope deviations causing wheelchairs to roll?

ADAguy

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Joined
Sep 11, 2013
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California
By what difference in slope >2% will an occupied (250lbs) manual WC begin to roll on its own on AC paving with hard wheels?

Is there a tolerance for distance between deviations in % of slope? (consider 4 points of contact with surface) those 4 points may be less than 30 x 48" between the centerlines of each wheel.
 
If you oil the axel of the wheelchair do you get a different value?
 
I think, through various potentially misapplied usage of several calculators, I determined an unspecified mass of 250 pounds requires a slope of 51% to overcome gravity and slide, assuming a CoF of .5 (which I think is some typical floor tile).

I'm pretty sure that ain't applicable to a wheelchair. There are way more journal articles on wheelchair movement and the mechanics thereof than I anticipated.

Really curious if there's a more obvious method than the pure physics of it.
 
If the brakes on the wheelchair are off then a COF of 0.5 is too high.
 
Inside or outside, wind speed, surface type, who's doin the whackin? Is it Tony the Tuna?
 
If the brakes on the wheelchair are off then a COF of 0.5 is too high.
Were you a schoolteacher cause I think that gave me an ah-hah moment and I found new tables to reference.

But now I'm coming up with less than a 1% slope would start a 250 pound mass in motion (albeit at a less than one-thousandth of a meter per second)

(And yes, I just imperialed and metriced at the same time there)
 
My question is what does the code say?

My uninformed impression is that if the code is not clear then the permit holder should be able to use any criteria not inconsistent with the code. In other words I do not see the need to be overly concerned with the precision.
 
My question is what does the code say?

My uninformed impression is that if the code is not clear then the permit holder should be able to use any criteria not inconsistent with the code. In other words I do not see the need to be overly concerned with the precision.

When the code says a "maximum" or a "minimum" it is providing you with an exact limit of tolerance. It is not implying any further tolerance. Anything beyond that is not in compliance with the prescriptive code.
The question becomes, what is the tolerance of the measuring device used to measure the "intolerant" code compliance?
Or: have I sought out and obtained - in writing - an alternative compliance measure other than the prescriptive code?

ADAGuy, I'm sure there's lots of people who could handle a main or cross-slope steeper than 2%. Heck, this guys Climbs stairs in his wheelchair:

Like every other rule in society ("SPEED LIMIT 65 MPH") 2% is a number that was likely selected more for simplicity of enforcement than for coefficient of friction statistics.

I worked on a physical rehab facility in eastern Africa, and tried to design it to ADA (or more precisely, the legacy British-influenced version of accessibility code). The problem was, it wasn't successfully preparing them for the 'real world' of hard-packed dirt roads, 20 degree ramps with 1 meter long landings, etc. Our goal was to make the structure accessible, but in the process, we were not training the users how to navigate the rest of their world that was less accessible.
 
The problem was, it wasn't successfully preparing them for the 'real world' of hard-packed dirt roads, 20 degree ramps with 1 meter long landings, etc. Our goal was to make the structure accessible, but in the process, we were not training the users how to navigate the rest of their world that was less accessible.
I don't see how that's in line with not discriminating, the basis of ADA and these codes and standards. If people can't enter because the ramp is too steep, they are discriminated against. The steep ramp is no different than a sign that says "no people of color may enter".
 
I don't see how that's in line with not discriminating, the basis of ADA and these codes and standards. If people can't enter because the ramp is too steep, they are discriminated against. The steep ramp is no different than a sign that says "no people of color may enter".
Wasn’t that one of the reasons for the original passage of the ADA?
 
By what difference in slope >2% will an occupied (250lbs) manual WC begin to roll on its own on AC paving with hard wheels?
I have been following along, and i’m still curious why you are asking. Sounds like you are trying to trying to gather data to challenge a code item.
 
I have been following along, and i’m still curious why you are asking. Sounds like you are trying to trying to gather data to challenge a code item.
Glad you asked, Serial litigants and their law firms file hundreds of cases using boiler plate but lacking specifics. Vertical barriers exceeding 1/2" are generally visible, but how does a gradual surface depression within a newly resurfaced access aisle prevent a plaintiff from entering a business?
Will a wheelchair (considering frictional resistance of user wheels and weight to the AC) without its break on, roll on its own if the variance in % of slope is > 2% and if so how much greater (2.5 - 3.5?)? Alternate methods and means allows for installation tolerances which can be shown to not be a barrier within reason. Plaintiff used a 6" smart level at a single point vs using a 24 - 48" SL within the cross and running slope of the aisle.
Note: just found a phone Ap for measuring slope angle of a surface, very cool; use it on a 8' straight edge in contact along the bottom of it.
 
It was an East African physical rehab facility. Much of the world they live in is either rural, so the entire goal of the physical environment of the rehab facility was to train them how to overcome obstacles in everyday life.
Many of them also live in areas that are impoverished, to the point where they are choosing between building a shorter steeper ramp and having money left over to buy food, or building a longer ramp that takes more concrete and then not buying food. (To give you an idea of the physical environment, the local hospital often had patients two to a bed, laying head-to-foot.)
Lastly, their society is generally much more interdependent, cohesive, and less of a "go it alone" approach than America. So for them the idea of "discrimination" is not an issue of limiting someone's opportunity to roll in a wheelchair independent of assistance; "discrimination" is the idea of not assisting in the first place.
 
Glad you asked, Serial litigants and their law firms file hundreds of cases using boiler plate but lacking specifics. Vertical barriers exceeding 1/2" are generally visible, but how does a gradual surface depression within a newly resurfaced access aisle prevent a plaintiff from entering a business?
Common sense doesn’t matter for litigation, you go by adopted code. You can argue construction tolerance, and you can hope common sense factors into the punishment. But all they have to do is show your conditions don’t meet the hard numbers.
 
Glad you asked, Serial litigants and their law firms file hundreds of cases using boiler plate but lacking specifics. Vertical barriers exceeding 1/2" are generally visible, but how does a gradual surface depression within a newly resurfaced access aisle prevent a plaintiff from entering a business?
LAHD's Neutral Accessibility Consultant, Evan Terry Associates, recently said they will accept any Smart Level slope reading of 2.3% or less, due to the varying accuracy of slope meters. ETA has reviewed many court cases, so I believe this is based on court precedent.
IIRC they use 2' long smart levels.
So, if you are getting readings of 2.3% or less on a 2' smart level, chances are you will prevail in court.

But the goal of serial litigants isn't to prevail in court. The goal is to do a shakedown and scare people into settling outside of court, then they move on to the next victim.
 
LAHD's Neutral Accessibility Consultant, Evan Terry Associates, recently said they will accept any Smart Level slope reading of 2.3% or less, due to the varying accuracy of slope meters. ETA has reviewed many court cases, so I believe this is based on court precedent.
IIRC they use 2' long smart levels.
So, if you are getting readings of 2.3% or less on a 2' smart level, chances are you will prevail in court.

But the goal of serial litigants isn't to prevail in court. The goal is to do a shakedown and scare people into settling outside of court, then they move on to the next victim.
See City of San Francisco People vs Potter Handy case filing of April 11 for a clearer understanding of this CA issue.
 
LAHD's Neutral Accessibility Consultant, Evan Terry Associates, recently said they will accept any Smart Level slope reading of 2.3% or less, due to the varying accuracy of slope meters. ETA has reviewed many court cases, so I believe this is based on court precedent.
IIRC they use 2' long smart levels.
So, if you are getting readings of 2.3% or less on a 2' smart level, chances are you will prevail in court.

But the goal of serial litigants isn't to prevail in court. The goal is to do a shakedown and scare people into settling outside of court, then they move on to the next victim.
That is the point, plaintiff's counsel will force to a mandatory settlement conf. where we may win but may not be able to recover our defense costs. The serial litigant appeared at a joint side meeting with a walker, not a WC but we are not allowed to challenge his standing. Plaintiff's CASp agreed that my readings were accurate vs his but his atty didn't agree. He is banking on the letter of the law vs common sense.
 
Were you a schoolteacher cause I think that gave me an ah-hah moment and I found new tables to reference.

But now I'm coming up with less than a 1% slope would start a 250 pound mass in motion (albeit at a less than one-thousandth of a meter per second)

(And yes, I just imperialed and metriced at the same time there)
1% is 1/8" / FT
And Isn't a !/4" accepted as a reasonable tolerance for Sidewalk aka "flat work?
Sounds like the math is off for "self starting" Wheel Chairs
 
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