Green Guide - Paragraph 13.4a
In general, the design of gangways in standing areas should meet the following requirements:
a). They should be provided so that all spectators are within 12m of a gangway or exit as measured along a line of unobstructed travel from the viewing position, so that they can move quickly into the exit system. It should be noted that the normal maximum egress time for all areas of viewing accommodation, standing or seated, is eight minutes (see Section 10.7).