防災・災害

Egress plan — office floor (fictional)

避難計画図（3 つの長さが、3 つの問いに答える）

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正本に書いてある決まりごと

Three different lengths, three different questions.

Common path	how far before you can choose between two exits
Dead end	how far into a corridor that goes nowhere
Exit access travel	how far to an exit once you can choose

Sprinklers lengthen all three —— which is why the egress plan and thesprinkler plan get read together（見本 145）.

Occupant load decides how many exits; travel distance decides where.Lengths are measured on the drawing at 1 px = 3 in: the dead end runs 20 ftfrom the corridor edge; from its far end it is 24 ft to the corridor centre(common path, where two ways open), then 12 ft to STAIR B, so 36 ft of exitaccess travel (88 ft the other way to STAIR A).These are the lengths of the path drawn, not the floor's governing values:both are measured from the most remote point of the space, which depends ondoor positions this plan does not show. Hence "path shown" in the table.Counted once each: the business area is 7,200 - 600 = 6,600 sq ft gross (44 people)and the conference room 600 sq ft net at 15 (40 people), 84 in all. A business floormay have a single exit only up to 49 people on a first story (29 on a second story,none above), so 84 needs two on any story.Limits: IBC 2021 Table 1006.2.1 (common path), 1020.5 (dead end), Table 1017.2(exit access travel: B, sprinklered 300 ft), Table 1006.3.4(2) (single exit).

日本語の見本 22（避難経路図）と対。

Occupancy, areas and distances are fictional.