Safety standards for public buildings are set by the Occupational Safety & Health Administration (OSHA). Included in the standards are the design of pedestrian passageways.
Twenty-Eight Inches Minimum
Twenty-eight inches is the minimum width for any walkway leading to an exit. The door must at least equal the passageway width if there is only one passageway.
If a large number of people is expected to use the passageway, the width must be more than 28 inches.
As a passageway approaches an exit, it may not decrease in width.
A passageway that has dual use with machinery such as fork-lifts must provide clearance of at least three feet wider than the largest equipment, or a minimum of four feet.