A Review of Building Evacuation Models - NIST Virtual Library

done so that if a node on the floor is blocked by smoke, only the routes on that floor and the floor
above will need to be recalculated. It also allows the occupants to maintain an individual
perspective of the building.
Walking speed throughout the model is a function of density, based on the observations of
Predtechenskii and Milinskii 13 . EXIT89 allows the user to choose between three different body
sizes labeled American (0.0906 m 2 ), Soviet (0.1130 m 2 ), and Austrian (0.1458 m 2 ). The
calculations used in EXIT89 use the specific body size to solve for the density of a stream, D, of
occupants as D=Nf/wL (m 2 /m 2 ) where N is the number of people in the stream, f is the area of
horizontal projection of a person, w is the width of the stream, and L is the length of the stream.
Predtechenskii and Milinskii report a maximum density of 0.92 m 2 /m 2 . The user can also specify
whether the occupants will move in emergency or normal conditions, and the difference in
calculation is shown below.
EXIT89 uses the velocity correlations for horizontal paths, down stairs and upstairs, depending
upon the density calculated in each movement situation, as given by Predtechenskii and
Milinskii 13 .
Horizontal Paths:
4
3
2
V = 112D
− 380D
+ 434D
− 217D
+ 57 (m/min) (A.8)
for density: 0 < D ≤ 0. 92
Down Stairs (↓):
V = Vm (m/min) (A.9)
↓ ↓
−0.39D
↓
where m 0.775 + 0.44e
⋅sin(5.61D
− 0.224)
=
↓
↓
Up Stairs (↑):
V = Vm (m/min) (A.10)
↑ ↑
3.45D↑ where m = 0.785 + 0.09e
⋅ sin15.7D
for 0 < D < 0.6;
↑
↑
↑
where m 0 .785 − 0.10sin(7.85D
+ 1.57)
for 0.6
≤ D ≤ 0. 92
=
↑
↑
↑
For emergency movement, equations (A.8) to (A.9) are adjusted by equation (A.11):
v = μ v
e
e
Where μ e = 1.49 – 0.36D for horizontal paths and through openings
μ e = 1.21 for descending stairs
μ e = 1.26 for ascending stairs
(A.11)
EXIT89 uses tables of velocities (based on occupant densities) for normal, emergency, and
comfortable movement along horizontal paths, openings, and stairways.
Output: The output consists of a complex occupant movement table that tracks the time and
corresponding node position of each occupant throughout the entire simulation. Also, the total
A-79