Tactile warning is an abrasive or knurled strip on a lever handle to indicate that the door leads to a hazardous area such as a boiler room, mechanical room, or loading dock. This requirement is no longer included in the Americans with Disabilities Act Accessibility Guidelines (ADAAG) or in ICC/ANSI A117.1, but it is a requirement of the Massachusetts Architectural Access Board (521 CMR):
26.11.4 Special hardware: Doors opening into hazardous areas shall have door-opening hardware which is knurled or has a roughened surface to give tactile warning to persons with visual impairments. Hazardous areas shall include but not be limited to loading platforms, boiler rooms, and electrical equipment rooms.
To access the Massachusetts Architectural Access Board requirements (521 CMR) online, click here.