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This website uses cookies to ensure you get the best experience on our websiteSubarea and Analysis of the Natural Landscape of Bijiashan Park in Shenzhen, Guangdong Province--《Acta Scientiarum Naturalium Universitatis Sunyatseni》2005年S1期
Subarea and Analysis of the Natural Landscape of Bijiashan Park in Shenzhen, Guangdong Province
LI Qing-yan~1,CUI Da-fang~1, HUANG Han-jie~2, LIAO Wen-bo~3(1.College of Life Science, South China Agriculture University, Guangzhou 510642, C2. Bijiashan Park,Shenzhen . School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China)
In this paper, authors survey the natural landscape of Bijiashan Park and research the style and characteristic of the park, then divide the natural landscape into three types: mountain landscape, flat area landscape and water landscape, and divide into two piece of landscape area, e.g. the mountanious forest region and traditional darden region, including 6 sub_regions. The result indicate that the landcape diversity of Bijiashan Park is higher, were characteristed by the mountain, lawn with little trees and waterboby, and transition zone, which the development plan could conbined Chinese traditional garden and occident garden feature. At last, authors give some suggestions for the park reconstruction.
【Key Words】：
【Fund】：
【CateGory Index】：
supports all the CNKI
only supports the PDF format.
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(C)2006 Tsinghua Tongfang Knowledge Network Technology Co., Ltd.(Beijing)(TTKN) All rights reservedPlanning and Travel Demand Modeling with TransCAD
Planning & Travel Demand
The World’s Most Powerful and Popular Travel Forecasting Software
TransCAD is the most comprehensive, flexible, and capable travel demand
modeling software ever created. TransCAD supports all important styles
of travel demand modeling including sketch planning methods, four-step
demand models, activity models, and other advanced disaggregate modeling
techniques, and comes with the most extensive set of traffic assignment
models ever assembled for use by planners and traffic engineers.
Many of the TransCAD enhancements and advantages come from improved
algorithms and improved software engineering implementations of the best
methods from the transportation science literature. Many key procedures
in TransCAD are multi-threaded, resulting in enormous speed improvements
on today’s multi-core processors. There is also support for distributed
processing for the largest models.
TransCAD continually breaks new ground as a tool for transportation
planners by improving, streamlining, and accelerating the demand
modeling process. TransCAD is the only package designed to facilitate
the implementation of best practices for travel forecasting and to
provide a mechanism for advancing the state of the art in transportation
modeling. Modeling with TransCAD is not limited to urban or regional
demand forecasting, but is directly applicable for modeling passenger
and freight flows at the state, national, and international level.
Demand Forecasting in a GIS Context
Travel forecasting models are used to predict changes in travel
patterns and the utilization of the transportation system in response to
changes in regional development, demographics, and transportation
supply. Modeling travel demand is a challenging task, but one that is
required for rational planning and evaluation of transportation systems.
TransCAD is the only modeling package that is GIS-based and fully
integrates geographic information system (GIS) and demand modeling
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includes many advanced features for transportation that are not
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There are many reasons why it is valuable to have a GIS as an integral
part of a travel demand forecasting package. First, GIS makes it
possible for planning models to be much more accurate. For example,
network distances are based on the actual shape of the road network and
a correct representation of highway interchanges.
Second, the whole modeling process is more efficient. Data preparation
is greatly facilitated and the database and visualization capabilities
catch errors before they cause modeling problems. With TransCAD, you and
others will have an easier time understanding how the model components
behave. For all of these reasons, less staff time is needed to implement
and maintain travel models.
A third important advantage of a GIS-based modeling system is the use of
the GIS itself and GIS-derived measurements directly in the modeling
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and applied for different geographic subareas. Similarly, TransCAD
brings new and much-needed capabilities for measuring geographic
accessibility.
Because they have similar architectures, TransCAD is the planning
package that integrates best with other institutional GIS software
TransCAD has native support for Esri Personal Geodatabases, Access,
Excel, and Google Earth. TransCAD can import data from virtually all
major GIS, CAD, and planning software packages. TransCAD is an open
system and can export data in ASCII, Shapefile, dxf, and Oracle Spatial
formats. TransCAD also links easily to ArcGIS, Google Earth, MapInfo,
and Maptitude.
On this page:
&TransCAD software is unique among travel demand forecasting
packages in many respects:
Fully-Windows Compliant: TransCAD supports Windows standards like .NET, ADO,
data exchange with Office, and the full complement of user
interface conventions.
Powerful Built-in Database: TransCAD includes a
powerful relational database and can work with data in all manner of
external databases and ODBC clients.
Outstanding Graphics: TransCAD provides high quality map output with dozens of thematic
mapping styles and options, unlimited colors, fully scalable line styles
and symbols, a complete set of freehand drawing and
annotation tools, labels that adjust to the
map scale, and built-in highway shields. There are specialized displays
for transit route systems, multi-modal desire lines, intersection diagrams, and
strip charts based upon linear referencing. Support for image layers makes it possible to overlay networks on top of
aerial photographs and satellite imagery. TransCAD also has multimedia
capabilities making it possible to integrate imagery, video, and web
links associated with transportation facilities.
A Single, Unified Solution Without Costly Add-Ons:
TransCAD is the only unified package that performs all the
desired functions. Other packages are limited to model
application, leaving model estimation, database support, GIS,
and often graphics and analytical postprocessing to other
Comprehensive Modeling Procedures: TransCAD has the
most comprehensive set of models. Because of its modern, unified design,
TransCAD makes it easy to perform integrated modeling of all
modes of transportation including car, HOV, truck, bus, rail,
bicycle, and pedestrian movements.
The Most Powerful Matrix Engine and Virtually Unlimited
Modeling Capacity: There are no hard limits on the number
of zones or the size of the networks to be modeled. There is
efficient storage for matrix and network data without
compromises that reduce processing speed.
Highest Quality Documentation: The TransCAD help system
includes a comprehensive travel demand modeling section that includes
numerous examples and tutorials.
Unparalleled GIS Integration: TransCAD embodies the
highest level of GIS integration through its internal GIS that has many
unique extensions for transportation. In addition, TransCAD integrates
best with other GIS software because it has similar data structures and
supports a vast array of popular data formats for vector databases and
raster images. TransCAD works well with Esri and MapInfo data and is
commonly used in conjunction with these other GIS software packages.
TransCAD Modeling Capabilities
TransCAD includes comprehensive tools for trip generation, trip
distribution, mode split modeling, traffic assignment, and all related
matrix and network processes. TransCAD includes all of the traditional
4-step models and significant variants, quick response models with
reduced data requirements, and advanced disaggregate demand models.
Caliper continually enhances TransCAD to incorporate the most up-to-date
methods for demand forecasting.
Trip Generation/Production
goal of trip production is to estimate the number of trips, by purpose,
that are produced or originate in each zone of a study area. Trip
generation is performed by relating frequency of trips to the
characteristics of the individuals, of the zone, and of the
transportation network. There are four primary tools for modeling trip
production, all of which are provided in TransCAD:
Cross-Classification: Cross-classification methods
separate the population in an urban area into relatively homogenous
groups based on certain socioeconomic characteristics. Then, average
trip production rates per household or individual are empirically
estimated for each classification. This creates a lookup table that may
be used to forecast trip productions. In TransCAD, you can use your
existing lookup tables, create new ones from survey data, and edit any
of the values. TransCAD provides several default cross-classification
tables including those for quick response methods and ITE rates based
upon employment or land use.
Regression Models: TransCAD supports estimation and
application of multivariable aggregate zonal models and disaggregate
models at the household or individual level. The first method uses data
aggregated at the zonal level, with the average number of trips per
household in the zone as the dependent variable and average zonal
characteristics as the explanatory variables. The second method uses
disaggregate data at the household or individual level, with the number
of trips made by a household or individual as the dependent variable and
the household and personal characteristics as the explanatory variables.
Discrete Choice Models: Discrete choice models use
disaggregate household or individual level data to estimate the
probability with which any household or individual will make trips. The
outcome can then be aggregated to predict the number of trips produced.
Population Synthesis: In addition to applying
disaggregate models to expanded survey samples, TransCAD provides for
the generation of synthetic populations whose tripmaking can be
forecasted with microsimulation.
Trip Attraction
The goal of Trip Attraction is to predict the number of trips attracted to each
zone or to a particular land use. In many ways, estimating attractions is similar
to estimating trip productions. Thus, cross-classification, regression, and discrete
choice methods can be used to estimate the number of trips attracted to a zone.
TransCAD also includes Institute of Transportation Engineers (ITE) trip rate data
for calculating trip attraction values for a single land use or mixed land uses.
Trip Balancing
In trip generation, separate models are used to predict productions and
attractions. This invariably leads to a discrepancy between the number
of intraregional trips produced in an area and the number of trips
attracted to an area. To conserve trips, balancing methods are provided
so that the number of attractions equals the number of productions. Trip
generation and attraction can be balanced flexibly to productions or
attractions or a linear combination thereof.
Trip Distribution
Trip distribution models are used to predict the spatial pattern of
trips or other flows between origins and destinations. Models similar to
those applied for trip distribution are often used to model commodity
flows, retail trade, and store patronage.
TransCAD provides numerous tools with which to perform trip
distribution, including procedures to implement growth factor methods,
apply previously-calibrated gravity models, generate friction factors,
and calibrate new model parameters.
In addition to doubly constrained trip distribution models that
ensure that the output flow matrix from trip distribution matches the
input productions and attractions, TransCAD includes tri-proportional
models which allow for another dimension of constraints. In
tri-proportional models, groups of cells in the P-A flow matrix are
required to sum to specified values. TransCAD allows the additional
dimension to be applied for both growth factor and gravity models.
Mode Choice Analysis
Mode choice models are used to analyze and predict the choices
that individuals or groups of individuals make in selecting the
transportation modes that are used for particular types of trips.
Typically, the goal is to predict the share or absolute number of trips
made by mode.
important objective in mode choice modeling is to predict the share of
trips attracted to public transportation. TransCAD provides procedures
for calibrating and applying mode choice models based on multinomial and
nested logit models, as well as legacy methods, and may be pursued at
either a disaggregate or aggregate zonal level.
Estimation of the parameters in the nested logit and multinomial logit
model is performed in TransCAD by the method of maximum likelihood,
which calculates the set of parameters that are "most likely" to have
resulted in the choices observed in the data. There is enormous
convenience in estimating and applying nested logit models in the same
software environment.
A special interface lets you draw the structure of your nested logit
model graphically. A companion model management window helps setup the
utility functions and data sources. With this interface, estimating
nested logit models has never been easier.
TransCAD supports choice set variation in both estimation and model
application which is important for accurate model specification.
TransCAD also provides support for coding user-defined mode choice
procedures in FORTRAN, C, JAVA, and C++.
P-A to O-D and Time of Day Transformations
TransCAD includes comprehensive tools that enable you to:
Convert productions and attractions to origins and destinations
Decompose a 24-hour trip table matrix into hourly trip tables
Convert person trips to vehicle trips
Apply peak hour factors
Super Fast, Super Convergent Advanced Traffic Assignments
TransCAD incorporates several breakthroughs in traffic assignment
methodology that facilitate more accurate analyses of road traffic and
the impacts of transportation improvements. All of the user equilibrium
methods can achieve very high levels of convergence and do so with
unprecedented fast computing times. Also, most of the methods take
advantage of multi-threading to run much faster on multi-core and
multi-CPU computers.
The advanced methods include:
Multi-modal toll road assignment
Origin user equilibrium
Path-based assignment
Multi-point equilibrium assignment
Combined distribution-assignment
Assignment with traffic signals and HCM intersection delay
Dynamic equilibrium traffic assignment
There is also an interface to running SATURN traffic assignments and preparing SATURN data for SATURN users.
Multi-Modal, Multi Class Assignment
Among the advanced methods is a very flexible, master multi-modal, multi-class equilibrium
or stochastic equilibrium assignment model that accommodates realistic multi-class entrance
to exit tolls in addition to traditional link tolls.
This is a generalized cost assignment
that uses class specific values of time and network use restrictions.
A wide array of
volume-delay functions have been pre-programmed and there is provision for user written
functions as well.
Level of Service (LOS) Calculators
TransCAD includes several modules for performing intersection LOS calculations
and calculating related HCM measures. These are very convenient to use as no data
transfer is required.
Origin User Equilibrium
Origin user equilibrium (OUE) can achieve much higher levels of convergence in less
computing time than traditional assignment algorithms. Caliper’s version can also
compute new solutions using a "warm start" from prior solutions which reduces the
time needed to perform impact assessment and to achieve feedback convergence. Also
select link analysis can be performed without having to rerun the assignment. OUE
supports all of the features of the multi-modal, class toll road assignment method.
Equilibrium Assignment with Volume Dependent Turning Delays
For more realistic treatment of networks with traffic signals, TransCAD
has a traffic assignment with HCM 2000 delay models for both signalized
and unsignalized intersections so that mixed networks can be modeled.
There is a convenient intersection editor, shared with Caliper’s
TransModeler traffic simulator, that reduces the effort required to
specify intersection geometry and signalization.
Dynamic Equilibrium Traffic Assignment
Standard traffic assignment models treat both the O-D demand and network
capacity as fixed and unvarying over a given time period. These models
also assume that all trips in the O-D matrix are completed within the
same time period. In reality, the temporal distribution of demand over
the period can vary greatly, leading to various levels of flow and
congestion. In addition, some O-D trips are longer than the assignment
time period, leading to potentially misleading results. The TransCAD
Dynamic Traffic Assignment (DTA) model addresses these problems by
dividing up O-D departures by time period, assigning O-D trips by time
period, and effectively managing the interaction of trips introduced to
the network at differing time periods. The flow and congestion results
are often more realistic than the standard traffic assignment models,
and capture the temporal distribution of congestion on the network more
effectively. There is also an option to modify the capacity of one or
more links to capture the effects of incidents and work zones.
This DTA for planners can run on very large networks, includes
calculation of spillback queue delay, and can generated congested skims
that vary by departure time for time of day and activity models. It has
important applications in evacuation planning and in preparing trip
tables for traffic simulation. Other DTA models are available in
TransModeler.
Assignment Utilities
Screenline Analysis:
Screenline analysis compares the results of trip assignment with the
traffic counts on roads. More precisely, it is a process of comparing
the directional sum of ground count traffic volumes across a screenline
or a cordon line with the directional sum of the assigned traffic
volumes across the same screenline or cordon line. Screenline analysis
is a useful tool for the calibration of trip assignment models, and it
can also be used for more general purposes of calculating flows that
cross a screenline.
Subarea Focusing: While forecasting transportation
demand for a region, you may be interested in performing a more detailed
investigation of traffic patterns within a subarea, such as the downtown
area. To facilitate subarea analysis, TransCAD provides a procedure that
lets you create an O-D trip table for any subarea. The reduced O-D table
may be used for performing a traffic assignment on a subarea network
which may be more detailed than the regional network, or used in a
traffic simulation for the subarea.
Assignment Differences: You can compare two flow tables
to find assignment differences. The assignment differences utility
creates a theme that graphically illustrates the locations and
magnitudes of differences. This tool is particularly useful for
analyzing the effects of changing network attributes, such as capacity
or VDF parameters, or employing different assignment techniques.
Select Link/Zone Analysis: You can create an
origin-destination matrix file that indicates the number of trips that
pass through a specified set of links or zones, sometimes referred to as
critical links or critical zones. You can also create an assignment
table that contains the component of flow on links that pass through a
specified set of links or zones.
Public Transit
transit is a specialty of TransCAD, with capabilities that greatly
exceed those of other planning packages. TransCAD is the only software
that has a realistic GIS-based representation of transit systems.
TransCAD has special data structures for handling transit routes in all
their natural complexity. Routes may be stored, displayed, edited, and
analyzed. An important feature is that transit routes can be directly
placed on the streets so that interactions between autos and transit can
be treated explicitly. Moreover, stops need not be located at street
intersections, but instead can be located where they really are and on
the correct side of the street.
Special visualization capabilities for transit make it easy to display
and label overlapping routes. There is an effective interactive route
editor that makes it straightforward to enter new routes and modify
existing ones.
TransCAD has the broadest set of transit pathfinding routines of any
package and includes the methods found in other packages. The latest
version has a new, generalized pathfinder that computes composite
characteristics for overlapping transit routes. This pathfinder improves
upon the UTPS, TRANPLAN, TP+, and EMME/2 methods and gives a good
estimate of the waiting time that travelers would experience prior to
boarding a transit route in the presence of overlapping service.
There is also the broadest set of transit assignment methods including
some innovative methods not found in other packages. These include a
stochastic user equilibrium method that deals with multiple service
alternatives, vehicle capacity, and optionally with dwell time and
user’s value of time. In New York City, the transit agencies have been
using TransCAD for nearly two decades because of these advanced
capabilities.
Transit Networks and Paths
TransCAD has special tools and procedures for creating and working with transit networks. Transit fares can be specified as flat, zonal, or mixed. Using transit networks and fare structures, you can solve shortest path problems, calculate transit path attributes (i.e. skims), and perform transit assignment.
TransCAD can process schedules and assist in developing network
attributes such as route headways.
TransCAD includes the most realistic and flexible transit pathfinding
and skimming methods. The key methods provide the multiple paths that
travelers will use and give the analyst fine control over access,
egress, and transfer properties.
Transit Assignment
Transit assignment models are used to
estimate the number of passengers that utilize segments in a transit
network as a function of transit level of service. These models take as
input a matrix of passenger flows between origins and destinations and a
transit network, and produce link level and aggregate ridership
statistics. TransCAD includes an array of sophisticated transit network
assignment procedures.
procedures include methods that are sensitive to fares and park and ride
access, as well as equilibrium assignments, which take account of the
capacity of transit service and the effect of ridership on crowding,
comfort, and, optionally through dwell time effects, on the travel time
on the route. These methods distribute the flow between a particular
origin and destination to multiple paths, based on their relative
attractiveness.
The transit assignment procedures produce a table of ridership at
every stop along each route in the transit network. Optional outputs
include critical link analysis, boarding and alighting counts,
stop-to-stop flows, route-to-route transfers, and aggregate ridership
counts. You can also save the paths utilized and visualize them
Non-Motorized Travel Analysis
With TransCAD you can have separate and fully integrated networks for
bicycles and pedestrians. Pedestrian links can be full street networks.
Walk links can be included in transit networks.
Road and Transit O-D Estimation
Accurate and up-to-date trip tables are critical inputs for
transportation planning models. Traditionally, the principal method of
collecting information on the spatial pattern of trips within urban
areas has been the large scale home interview survey. Unfortunately,
home interview surveys of the necessary sample size are prohibitively
expensive and difficult to implement, and are therefore rarely done. In
contrast, traffic counts on highway links are inexpensive to perform and
are routinely collected in many areas. It is thus extremely attractive
to have a method to create or update trip tables based upon traffic
TransCAD provides very flexible and effective procedures for estimating
and/or updating an origin-destination matrix based upon a sample of
network link traffic counts and an optional, initial or base trip table.
Freight Applications
TransCAD has been designed to facilitate freight demand modeling as well as passenger models. TransCAD
can manage all of your freight data no matter how many origins, destinations, shipments, or commodities
are involved. TransCAD offers a complete solution for modeling commodity flows and truck movements. Freight
traffic can be easily assigned to the transportation network and there are also specialized assignment
procedures available for rail waybill assignment.
Advanced Geographic Editing Tools
editing tools provide an effective means of improving the geography and
topology of planning networks that may originally have only simple,
straight-line representations. Specifically, TransCAD includes tools
Dualizing, merging, and setting directionality of segments
Improving the geographical accuracy of line segments through
conflation
Copying and pasting line segments from one layer to another
Creating highway interchanges with a minimum of effort.
Consequently, planning networks can now be fully realized as GIS
entities and visualized directly with appropriate accuracy, shape,
geometry, and directionality. Many users will find these tools
indispensable for transforming TIGER/Line layers into a suitable basis
for planning and traffic applications as well as for improving the line
layers that are used for other types of transportation, including rail,
transit, and air networks. In addition, all of these operations can be
undone and redone at will.
Data Access
TransCAD includes utilities that model developers will find
indispensable for data preparation.
Geocoding: Virtually all forms of survey data can be analyzed in TransCAD.
For most modeling purposes, each survey will be geocoded to the respondent’s primary location.
For traveler surveys, each survey will most commonly be geocoded to their residence.
Access Census Data Directly: Census data are very valuable in urban transportation analysis.
TransCAD comes with extensive Census data. TransCAD also provides procedures for importing
specialized Census data. There are procedures for importing data from the Census Transportation
Planning Package (CTPP). The CTPP data are among the most valuable datasets available for
transportation planners. There are also methods for accessing the American Community Survey (ACS)
which provides the most up-to-date Census information available.
There is also a procedure provided for accessing the Public Use Microdata Samples (PUMS). PUMS
contains complete household records from the US Census for a sample of the population, and is a
valuable source of disaggregate data. The TransCAD procedure organizes the data so that you can open
PUMS files directly and view the data either by household or by individual.
A World of Data: Increasingly there are many other data sets available for use with TransCAD for many
other countries and regions. Caliper can help you identify these data sets.
Import Networks and Trip Tables: TransCAD provides tools for importing networks and network data from
a variety of stand-alone transportation planning packages. These networks are converted into GIS databases
that can be used for all types of planning, modeling, and mapping applications. TransCAD provides a
seamless import capability for transportation planning network files in TP+, EMME/2, TRIPS, QRSII, TMODEL
and TRANPLAN ASCII formats, usually with no preprocessing necessary. Other data can be imported from ASCII
and many other formats.
Programming TransCAD and Batch Mode Processing
TransCAD provides a wealth of facilities for building integrated
model applications, performing scenario management, creating custom user
interfaces for planning models, and running demand models without user
intervention (i.e., in batch mode). In addition to running models
interactively, TransCAD provides great flexibility in building complete
model applications, with attractive user interfaces that are easy to
learn and use. Models can be compiled and published or distributed to
third parties with their key properties locked down to protect
inappropriate modifications.
TransCAD comes with its own scripting language, GISDKTM, the GIS
Developer’s Kit. GISDK is a simple object-oriented scripting language
that provides hundreds of powerful modeling and GIS functions. GISDK
includes a compiler and a debugger and provides all the tools needed to
create model scripts, build add-ins to automate repeated actions, or
create custom applications. TransCAD can also be scripted with Python
and called from any .NET language.
Innovative Interactive Batch Capture
There is an innovative batch processing system that is built in to
TransCAD. In addition to creating scripts the old fashioned way by
writing them from scratch, TransCAD lets you create scripts
interactively by clicking menu items, choosing parameters in dialog
boxes, and saving the corresponding script. This can then be edited
further in the conventional manner.
Caliper also provides templates for common modeling streams including
feedback so that you can adapt the templates for your own purposes. The
GISDK and the batch facility let you create beautiful Windows user
interfaces for your models.
User Friendly, Push Button Model Interfaces and Scenario Manager
For most planning models, Caliper offers a pre-designed model user
toolbox interface that can be easily modified for your model. The Model
User Interface Toolbox provides a custom interface that allows you to
run a model with the click of a button, as well as provides features to
store and create scenarios. You can generate and store any number of
scenarios. Scenarios are defined by a scenario name, a set of input
files, output files, and model parameters, and there are special
features in the toolbox to assist in setting up scenarios. Once you have
setup a scenario, the model steps for a scenario can be run separately
or run as a group. With a click of a button you can graphically view
model outputs and scenario differences.
TransCAD Model Manager
The TransCAD Model Manager is a graphical environment for building
integrated travel demand planning models and running scenarios. The
Model Manager allows you to create, understand, and edit planning models
based on a flowchart interface. It also provides a wide variety of
advanced scenario management tools.
With the model manager, you can interactively specify the order of the
modeling steps to be performed, select all of the input and output
files, and edit the model procedure parameters. The easy-to-use
interface also documents the model and its components, and makes it
simple to set up distributed processing.
Scenario Management
The model manager includes a powerful scenario management facility.
Once you have a working model, you use the Scenario Toolbox to organize
the parameters for different runs of the model and to run the scenario.
The Scenario Toolbox is the control panel for creating new scenarios,
for editing and reviewing their parameters (input and output data
files), and for running the model under different scenarios.
Object-oriented methods are used to maintain the relationships among
sets of interrelated scenarios. Each scenario allows use to define the
base directory that the model files use and optionally all the relevant
input and output file names and parameters for the scenario.
Additionally, sub or "child" scenarios can be created that is a subset
of another scenario. The child scenario by default inherits all
parameter values from its parent. Whenever the parent scenario’s
parameters change, the child's values change automatically greatly
streamlining the model process.
Planning and Travel Demand
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