![](bg6.png)
width correlates with egress routes, long hallways
have many adjoining rooms, and exits are distributed
in a uniform manner. The main difference between
the results for each building is the performance of the
width heuristic. In the CSULB FM building, corridor
width corresponds closely with egress routes, while
in the custom building the correlation is weaker. The
simple signage heuristic also yields different results
in these two buildings. In the custom building, the
top left and top right exits are not visible throughout
most of the building and are thus highly underutilized.
Meanwhile, the exits in the CSULB FM building have
a much higher level of visibility throughout the build-
ing and are used more effectively.
6.2 One Heuristic
When only a single heuristic is used, the results vary
greatly between heuristics (see Figure 4). The signage
heuristic performs well in all types of building lay-
outs tested. This suggests that if pedestrians choose
an egress route based upon well-designed signage,
pedestrians can efficiently egress from a building even
when completely unfamiliar with the layout of the
building. Using simple signage, the egress times are
still as good as or better than any other heuristic in
the building layouts considered. This highlights the
importance of even minimal building signage in as-
sisting in pedestrian egress.
The shortest-leg heuristic leads to slow egress
times in almost every building layout considered. In
many instances, the shortest-leg heuristic does not
even outperform a random choice policy. As dis-
cussed in Section 3, when the end goal is not known,
choosing the route which is closest to the pedestrian
becomes the shortest-leg first heuristic. This greedy
route selection heuristic provides no guarantee that
the route chosen will even lead to a direct exit. Ad-
ditionally, when distance is the sole means of eval-
uating a route, congestion is a common occurrence.
Pedestrians who are closest to a given doorway will
select that doorway regardless of what side they are
on or which direction other pedestrians are moving.
Thus, the pedestrians on opposite sides of the door-
way will converge at the doorway causing a bottle-
neck, and pedestrian flow rates through the doorway
will be greatly inhibited. Interestingly, the shortest-
leg heuristic performs remarkably well in the USU
Business Building (see Figure 4). This building is
configured ideally so that greedily selecting the clos-
est visible route actually leads pedestrians to an exit
in a fairly efficient manner. One reason that this is the
case is the double doors on most of the rooms. This
allows the pedestrian to explore routes without having
to backtrack, which is discouraged by the algorithm.
Additionally, the end rooms have doorways adjacent
to exits, which facilitates egress in this situation.
Similar to the shortest-leg heuristic, the fewest
turns heuristic also leads to poor performance. The
results are not shown here. The intuition behind the
fewest turns heuristic is to select a route that is as di-
rect as possible. However, considering only the next
route goal is too short-sighted and leads to routes
which are drastically less direct than they could be.
Without prior knowledge about the building layout,
though, this short-sightedness cannot be overcome.
For the building layouts considered in this paper,
the width heuristic leads to average egress times when
compared to the other heuristics. For the CSULB-FM
building, choosing the widest route leads to finding an
exit sooner than selecting a route by any other heuris-
tic except for signage. In the remaining buildings, the
width heuristic performs worse than the congestion
heuristic, but still significantly outperforms a random
policy.
The congestion heuristic does not necessarily pro-
vide an indication of which route leads to an exit,
especially when none of the pedestrians have any
knowledge regarding the building layout. However,
avoiding congestion still improves the overall egress
time by helping prevent bottlenecks and increasing
the overall smoothness of pedestrian flow. This al-
lows more routes to be explored in less time, which
leads to better egress times. Although (due to space
limitations) the results are not shown here, the con-
sensus heuristic also relieves congestions at bottle-
necks and improves pedestrian flow so that routes
can be explored in a more efficient manner. To be
most effective, the congestion and consensus heuris-
tics should be combined with another heuristic such
as width or signage which provide an indication of an
egress route.
6.3 Multiple Heuristics
After considering each heuristic individually, we then
combine several heuristics to further improve perfor-
mance (see Figure 5). Although many different com-
binations could be tried, in this paper, we consider
combining the simple signage and width heuristics
(SS-W) and the shortest-leg, simple signage, width,
and congestion (SL-SS-W-C) heuristics. When width
is the sole heuristic applied, the egress times are too
slow to be reliable in an emergency. The simple sig-
nage heuristic is also slower than desired but is still
the best alternative to the signage heuristic (which
may not be realistic for many buildings) when only
a single heuristic is applied. The goal of combining
SIMULATING PEDESTRIAN ROUTE SELECTION WITH IMPERFECT KNOWLEDGE
151