Is the travel distance for the purpose of developing life safety egress plans, fire hose coverage, or something else?
This question came in as travel distance for the development of life safety plans (means of egress).
NFPA 101 gives guidance on measuring travel distance for means of egress:
7.6* Measurement of Travel Distance to Exits.
7.6.1*The travel distance to an exit shall be measured on the floor or other walking surface as follows:
(1) Along the centerline of the natural path of travel, starting
from the most remote point subject to occupancy
(2) Curving around any corners or obstructions, with a 12 in. (305 mm) clearance therefrom
(3) Terminating at one of the following:
(a) Center of the doorway
(b) Other point at which the exit begins
(c) Smoke barrier in an existing detention and correctional occupancy as provided in Chapter 23
Let me answer from the perspective of a commercial plans examiner that reviewed to the 2012 IBC.
- Diagonal travel distances are only not questioned if across a space that has to remain open for its intended use. And even then, as the reviewer I would ask for an explanation of why it has to remain open. Sport courts can be obstacle courses, wide corridors can have furniture lining the walls, etc. Note that the IBC does not discuss corners like NFPA 101 does.
- I would prefer the measured distance to be at least 18"/22" from all walls, based on the corridor width minimum requirements. This width is based on (historic) human size. If the measurement is taken closer to the walls, I would question it.
Note that in both cases, if you give me a good enough justification, I would allow either one to be relaxed a little.
One typical example of measuring travel distance (TD) in a diagonal approach is in a mall structure. Since mall concourse/corridor is wide and normally open for occupants to stroll, angular measurement of TD is possible. Also on a driveway of a parking area it is typical to do a TD diagonally and very much acceptable with the authorities having jurisdiction (AHJ).
I'm working on an exercise studio with one big open room and dealing with a plan examiner who insists travel distance is measured along walls leading to an exit, rather than diagonally across the space. To me this is absurd. Thoughts?
You probably have the answer by now. It's about life safety, you should always measure the maximum possible path. Occupants may be using the wall to find their way in a dark or smoke filled building.
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