1961 American National Standards Institute (ANSI) created construction requirements for the physically impaired. These were voluntary standards, not adopted as legal requirements, and were generally not implemented.
1964 Civil Rights Act: vehicle for future enforcement efforts aimed at so-called barrier legislation
1968 Architectural Barriers Act (ABA) for the first time required compliance with ANSI standards, but only for federal buildings
1973 Rehabilitation Act required that federally-funded buildings (not just federal buildings) comply with "non-discriminatory building practices," i.e., ANSI-type standards
1980s was a decade in which individual states began passing accessibility legislation (Michigan, California, North Carolina were among the first to create consolidated codes, in 1982)
1990 Americans with Disabilities Act (ADA) is the relatively recent federal law requiring accessible buildings (among other things) more or less universally. The law became effective in 1992, and the specifically architectural "barriers" part became effective only in January of 1995. It essentially mandates ANSI-type standards for all construction, including existing buildings. There are exceptions for residential construction, and for various existing or historic conditions not easily remedied. Cornell's Sibley and Rand Halls had been in non-compliance for years before relatively recent improvements (elevators, etc.).
For a more personal evaluation of the ADA's history and impact, see this NY Times Opinion article by Ben Mattlin (July 25, 2015).
the main one is to actually provide for all parts of a building to be accessible for people with disabilities, by providing ramps, elevators, minimum dimensions for corridors and doors, etc.
32" min. width at point (e.g., door)
36" minimum corridor width
5'-0" minimum diameter circle for turning (wheelchair)
control protruding objects such that nothing sticks out from a wall more than 4" unless it is less than 27" from the floor (this refers to objects "parallel" to the direction of travel).
Protruding objects in the Hartell Gallery at Cornell (photo by J. Ochshorn, April 2015)
These days, protruding objects create a hazard, not just for the visually impaired, but for all distracted humans (image from NY Times article cited).
Need more evidence? Watch this video about texting and walking at the same time.
Protruding object on food truck in the circulation path behind Milstein Hall, Cornell University (photo and annotation by J. Ochshorn)
The geometry of the wall at an exit stair in Cornell's Physical Sciences Building creates a "protruding object" (photo at left by Abram Collette; photo and annotations in middle by Jonathan Ochshorn, Sept. 2018; photo at right showing corrected handrail by Shu Chen Xu with Leon Carranza holding the handrail, Oct. 2021)
ramps generally have maximum slope of 1:12 for a rise of 30" maximum, after which point a landing is required. 1:8 is OK for short distances only (3" max. rise).
guard rails and handrails have specific dimensional requirements (e.g., 1-1/4" - 1-1/2" diameter gripping surface with 1-1/2" clear space between the rail and the wall)
stairs have max. riser height = 7" and minimum tread length = 11"; also nosing profile should be "continuous" and smooth rather than articulated.
handrails must extend 12" beyond last (top) riser, horizontally; must extend one tread length (i.e., 11 inches) beyond the last riser at the bottom, sloping; and/or must be continuous.
provide space on both sides of doors to allow for wheelchair access (see diagrams in ADA guidelines).
see details in ADA guidelines for accessible bathrooms and toilet stalls.
Disclaimer: Students are responsible for material presented in class, and required material described on course outline. These notes are provided as a tentative outline of material intended to be presented in lectures only; they may not cover all material, and they may contain information not actually presented. Notes may be updated each year, and may or may not apply to non-current versions of course.
first posted Sept. 14, 2012 | last updated: Oct. 5, 2021
2007 – 2021 J. Ochshorn. All rights reserved. Republishing material on this web site, whether in print or on another web site, in whole or in part, is not permitted without advance permission of the author.
