<s>
UrbanSim	B-Application
is	O
an	O
open	B-License
source	I-License
urban	O
simulation	O
system	O
designed	O
by	O
Paul	O
Waddell	O
of	O
the	O
University	O
of	O
California	O
,	O
Berkeley	O
and	O
developed	O
with	O
numerous	O
collaborators	O
to	O
support	O
metropolitan	O
land	O
use	O
,	O
transportation	O
,	O
and	O
environmental	O
planning	O
.	O
</s>
<s>
coordinates	O
the	O
development	O
of	O
UrbanSim	B-Application
and	O
provides	O
professional	O
services	O
to	O
support	O
its	O
application	O
.	O
</s>
<s>
The	O
development	O
of	O
UrbanSim	B-Application
has	O
been	O
funded	O
by	O
several	O
grants	O
from	O
the	O
National	O
Science	O
Foundation	O
,	O
the	O
U.S.	O
Environmental	O
Protection	O
Agency	O
,	O
the	O
Federal	O
Highway	O
Administration	O
,	O
as	O
well	O
as	O
support	O
from	O
states	O
,	O
metropolitan	O
planning	O
agencies	O
and	O
research	O
councils	O
in	O
Europe	O
and	O
South	O
Africa	O
.	O
</s>
<s>
Reviews	O
of	O
UrbanSim	B-Application
and	O
comparison	O
to	O
other	O
urban	O
modeling	O
platforms	O
may	O
be	O
found	O
in	O
references	O
.	O
</s>
<s>
The	O
first	O
documented	O
application	O
of	O
UrbanSim	B-Application
was	O
a	O
prototype	B-Application
application	O
to	O
the	O
Eugene-Springfield	O
,	O
Oregon	O
setting	O
.	O
</s>
<s>
In	O
Europe	O
,	O
UrbanSim	B-Application
has	O
been	O
applied	O
in	O
Paris	O
,	O
France	O
;	O
Brussels	O
,	O
Belgium	O
;	O
and	O
Zurich	O
,	O
Switzerland	O
with	O
various	O
other	O
applications	O
not	O
yet	O
documented	O
in	O
published	O
papers	O
.	O
</s>
<s>
The	O
initial	O
implementation	O
of	O
UrbanSim	B-Application
was	O
implemented	O
in	O
Java	B-Language
.	O
</s>
<s>
The	O
software	B-Architecture
architecture	I-Architecture
was	O
modularized	O
and	O
reimplemented	O
in	O
Python	B-Language
beginning	O
in	O
2005	O
,	O
making	O
extensive	O
use	O
of	O
the	O
Numpy	B-Application
numerical	O
library	O
.	O
</s>
<s>
The	O
software	O
has	O
been	O
generalized	O
and	O
abstracted	O
from	O
the	O
UrbanSim	B-Application
model	O
system	O
,	O
and	O
is	O
now	O
referred	O
to	O
as	O
the	O
Open	O
Platform	O
for	O
Urban	O
Simulation	O
(	O
OPUS	O
)	O
,	O
in	O
order	O
to	O
facilitate	O
a	O
plug-in	O
architecture	O
for	O
models	O
such	O
as	O
activity-based	O
travel	O
,	O
dynamic	O
traffic	O
assignment	O
,	O
emissions	O
,	O
and	O
land	O
cover	O
change	O
.	O
</s>
<s>
OPUS	O
includes	O
a	O
Graphical	B-Application
User	I-Application
Interface	I-Application
,	O
and	O
a	O
concise	O
expression	O
language	O
to	O
facilitate	O
access	O
to	O
complex	O
internal	O
operations	O
by	O
non-programmers	O
.	O
</s>
<s>
Beginning	O
in	O
2012	O
,	O
UrbanSim	B-Application
was	O
re-implemented	O
using	O
current	O
Scientific	O
Python	B-Language
libraries	O
such	O
as	O
Pandas	O
.	O
</s>
<s>
UrbanSim	B-Application
Inc	O
.	O
has	O
developed	O
the	O
UrbanSim	B-Application
Cloud	O
Platform	O
that	O
deploys	O
simulations	O
on	O
the	O
cloud	O
for	O
scalability	O
,	O
enabling	O
hundreds	O
or	O
even	O
thousands	O
of	O
simulations	O
to	O
be	O
run	O
simultaneously	O
,	O
and	O
a	O
web	O
browser	O
based	O
User	O
Interface	O
that	O
features	O
a	O
3D	O
web	O
map	O
view	O
of	O
inputs	O
and	O
outputs	O
from	O
the	O
simulation	O
.	O
</s>
<s>
UrbanSim	B-Application
models	O
have	O
been	O
pre-built	O
for	O
400	O
metropolitan	O
areas	O
within	O
the	O
United	O
States	O
at	O
a	O
census	O
block	O
level	O
of	O
detail	O
.	O
</s>
<s>
Users	O
anywhere	O
in	O
the	O
world	O
can	O
also	O
build	O
UrbanSim	B-Application
models	O
using	O
zone	O
and	O
parcel	O
templates	O
,	O
by	O
uploading	O
local	O
data	O
and	O
using	O
the	O
cloud	O
resources	O
to	O
auto-specify	O
and	O
calibrate	O
the	O
models	O
using	O
local	O
data	O
.	O
</s>
<s>
Details	O
are	O
available	O
at	O
www.urbansim.com	O
.	O
</s>
<s>
Earlier	O
urban	O
model	O
systems	O
were	O
generally	O
based	O
on	O
deterministic	B-General_Concept
solution	I-General_Concept
algorithms	I-General_Concept
such	O
as	O
Spatial	O
Interaction	O
or	O
Spatial	O
Input-Output	O
,	O
that	O
emphasize	O
repeatability	O
and	O
uniqueness	O
of	O
convergence	O
to	O
an	O
equilibrium	O
,	O
but	O
rest	O
on	O
strong	O
assumptions	O
about	O
behavior	O
,	O
such	O
as	O
agents	O
having	O
perfect	O
information	O
of	O
all	O
the	O
alternative	O
locations	O
in	O
the	O
metropolitan	O
area	O
,	O
transactions	O
being	O
costless	O
,	O
and	O
markets	O
being	O
perfectly	O
competitive	O
.	O
</s>
<s>
Housing	O
booms	O
and	O
busts	O
,	O
and	O
the	O
financial	O
crisis	O
,	O
are	O
relatively	O
clear	O
examples	O
of	O
market	O
imperfections	O
that	O
motivate	O
the	O
use	O
of	O
less	O
restrictive	O
assumptions	O
in	O
UrbanSim	B-Application
.	O
</s>
<s>
Rather	O
than	O
calibrating	O
the	O
model	O
to	O
a	O
cross-sectional	O
equilibrium	O
,	O
or	O
base-year	O
set	O
of	O
conditions	O
,	O
statistical	O
methods	O
have	O
been	O
developed	O
to	O
calibrate	O
uncertainty	O
in	O
UrbanSim	B-Application
arising	O
from	O
its	O
use	O
of	O
Monte	B-Algorithm
Carlo	I-Algorithm
methods	I-Algorithm
and	O
from	O
uncertainty	O
in	O
data	O
and	O
models	O
,	O
against	O
observed	O
data	O
over	O
a	O
longitudinal	O
period	O
,	O
using	O
a	O
method	O
known	O
as	O
Bayesian	O
Melding	O
.	O
</s>
<s>
In	O
addition	O
to	O
its	O
less	O
strong	O
assumptions	O
about	O
markets	O
,	O
UrbanSim	B-Application
departs	O
from	O
earlier	O
model	O
designs	O
that	O
used	O
high	O
levels	O
of	O
aggregation	O
of	O
geography	O
into	O
large	O
zones	O
,	O
and	O
agents	O
such	O
as	O
households	O
and	O
jobs	O
into	O
large	O
groups	O
assumed	O
to	O
be	O
homogeneous	O
.	O
</s>
<s>
Instead	O
,	O
UrbanSim	B-Application
adopts	O
a	O
microsimulation	B-Application
approach	O
meaning	O
that	O
it	O
represents	O
individual	O
agents	O
within	O
the	O
simulation	O
.	O
</s>
<s>
One	O
of	O
the	O
motivations	O
for	O
the	O
UrbanSim	B-Application
project	O
is	O
to	O
not	O
only	O
provide	O
robust	O
predictions	O
of	O
the	O
potential	O
outcomes	O
of	O
different	O
transportation	O
investments	O
and	O
land	O
use	O
policies	O
,	O
but	O
also	O
to	O
facilitate	O
more	O
deliberative	O
civic	O
engagement	O
in	O
what	O
are	O
often	O
contentious	O
debates	O
about	O
transportation	O
infrastructure	O
,	O
or	O
land	O
policies	O
,	O
with	O
uneven	O
distributions	O
of	O
benefits	O
and	O
costs	O
.	O
</s>
<s>
Recent	O
work	O
has	O
also	O
emerged	O
to	O
integrate	O
new	O
forms	O
of	O
visualization	B-Application
,	O
including	O
3D	O
simulated	O
landscapes	O
.	O
</s>
