Hi Kent,Excellent question! I have investigated ADA Ramos in a number of states. Generally, if the ramp is less then the required 1:12 and 2% there is no issue of course. The problems arise when those requirements are exceeded. Those limits were set in place for a reason- safety and maneuverability of the users. My designs are set as a Not To Exceed parameter. Contractors should easily be able to meet those requirements. Allowances over the required limits negate those limits in my opinion. If your design is so tight that these critical design features for ADA cannot be easily met then it's possible the design should be re-evaluated. If the contractors are wanting an allowance for workability- then allow them to reduce the 1:12 and 2% to lesser slopes- that's their tolerance. These are requirements that should be easy enough to meet. If there is difficulty in meeting these maximum limits, that is what should be addressed- why? I don't think allowing a tolerance on an upper limit for an ADA application Is the right thing to do. "1:10 is close enough" becomes the norm and the ramp is in violation and will be. If ADA does not allow for a tolerance allowing excess, then there should be no allowance above the limit. If they want to construct below the requirements- have at it all day. Our focus is the safe access of ADA users not the comfort and ease of the contractor.
Lori Cox, PEPrincipal EngineerTEERO