Update: There are some code changes coming which could affect the answer to this question. Refer to this article for more info.
Are automatic operators required by the ADA Standards and ICC A117.1 – the predominate accessibility standards used in the US?
These standards do not require automatic operators in order for a door to be considered accessible. There are two sections of these standards which address doors – one for manual doors and one for automatic doors. If a door meets the requirements for a manual door that are listed in the applicable standard, an automatic operator is not required. Of course, an auto operator may be used for convenience even if it is not specifically required, and there may be local codes that are more stringent than the national standards.
The requirements for a manual door include a minimum clear width, maneuvering clearance as defined in the standard, a maximum opening force and closing speed, a flush surface at the bottom of the door on the push side, hardware that operates without tight grasping, pinching, or twisting of the wrist, and several other requirements. If a door is on an accessible route and can not meet the criteria listed in the standards, then adding an automatic operator may bring the door into compliance; automatic doors are not subject to some of the limitations stated for manual doors.
For detailed information about the requirements for manual doors and automatic doors, refer to sections 404.2 and 404.3 of the ADA Standards and/or ICC A117.1 (these standards are very similar). Also check local codes to ensure that there are no additional requirements for automatic doors.