Bonde 4
Richard Bonde
PHYS/MATH 714
Problem: Lawful Capacity
To determine the maximum capacity a room can have, the fire marshal of the jurisdiction where the building is, will come and take measurements of the room and inspect it for fire code. The determination of the maximum capacity will usually be determined by what the room will be used for. Some examples include:
· Classrooms
· Dance halls
· Bars
· Banquet halls
· Meeting room
· Restaurant
According to the Northamptonshire fire and rescue service, the maximum capacity allowed rest on mainly two things [1]:
1. People per area
2. Evacuation time
The allowed number of people per area depends on the examples above. For instance, dancing halls will count 1 person per square meter while a mostly standing drinking establishment will count 3 persons per square meter. [1]
The evacuation time given by the Northamptonshire fire and rescue service is 2-2.5 minutes. [1] It is assumed that this will be a likely evacuation time for most rooms as the travel time of the fire was most likely considered. The evacuation time of the room is directly related to the number of exits in the room. If there is to be only one exit, the maximum load of people shall be restricted to 50 people. The 50 person maximum for one exit seems to be consistent with most buildings numbers. The protocol also states that if there are two or more exits, a person shall be able to turn their back to the fire and exit out of the room. The environmental health and safety division of Cal State Fullerton has compiled the following list of requirements for classrooms: [2]
· All occupant loads over 50 must have two exit doors.
· Exit doors serving occupant loads over 50 must swing out and must be at least 28 inches wide.
· All rooms with an occupant load over 100 persons must have panic hardware or no latch on the door.
· All rooms holding over 50 persons are required to have signs listing the maximum occupant load of the room.
· When two exits are required, they must be separated ½ of the room’s longest diagonal distance.
· Exits from a room may pass through one accessory room to the corridor. This room must not be locked or contain hazardous materials or combustibles.
· The design criterion for state university classrooms is 15 feet per occupant. It is permissible, with proper aisles, to increase the load to 10 feet per occupant.
· There may be no more that 6 intervening seats or desks to the aisle (14 seats maximum per row).
· Aisle ways between desks should be 22 inches wide. 12 inches is the absolute minimum width allowable on a short-term basis.
· Exit aisles must be 3 feet wide with seats on only one side and 3 ½ feet wide with seats on both sides. The aisle can be 30 inches wide if there are 60 seats or less.
Approach:
It is obvious that the maximum capacity requirements are based off of persons per area, number of exits, location and size of the exits and evacuation time. The object would then be to design a computer program that can allow the user to create a room with a specified area and furniture. Then, what's thought to be the maximum occupancy would be put in at random positions in the room. Using a grid like system (take the average size of a person to be one grid space, the furniture can be estimated according to that standard) and average speeds of a normal persons stride, they can figure out an estimate of evacuation times for the room.
A simple model will be created to start with using a room with only one exit and the 50 person maximum. The randomly generated people in the room will be required to "walk" towards the exit. Only moves towards the door will be allowed. The people in the room cannot walk through furniture or other people. The simple model can account for normal walking pace and normal stride lengths. Once this model works, there will be options to account for elderly people, handicapped people, children and whatever else needed to simulate the room. The program should also take into account that in the event of a fire, people might not casually walk towards the exit and may run. A probability can be accounted for so many of the people in the room who will run or not.
Once the single exit model works, the program should be able to handle more than one exit. Determining one exit or the other will come from the steps required to get to the exit (i.e. not straight line distance) and also accounting for traffic of people. It might be an advantage to take a longer exit if there are too many people at the other.
Example:
Figure 1
Figure 1 shows an example set-up of a classroom. The green squares indicate people, the dark squares are furniture and the red outline is the exit. Once the simulation runs, the green squares will attempt to approach the red exit. In this case, they can only move to the left or down, one square at a time. If they encounter another person, and they can't move the other direction, they must stop. The simulation will run and count how long it takes for the room to clear.
References
[1] "Licensing Act 2003: Applicants Information Essential for Satisfying the Public Safety Licensing Objective," Northamptonshire Fire and Rescue Service
[2] Classroom Occupant Load, Environmental Health and Safety, California State University, Fullerton, http://ehs.fullerton.edu/SafetyGuidelines/ClassroomOccupantLoad.aspx