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Tips, Trips, and Traps of TransCAD Modeling
LSA Associates, Inc. September 2001 North Carolina MPO Conference
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Agenda Why Model? Why Jurisdictions Convert to TransCAD?
The Transportation Model GIS Developer’s Kit Applications
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Why do we model the transportation network?
Why Model? Why do we model the transportation network?
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Why Model? To consider the effects of land use, transportation, and air quality To determine infrastructure needs, costs, and timing as growth occurs To analyze land use and transportation alternatives To provide a consistent platform for travel forecasting Required by the federal government for metropolitan areas
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The History of Travel Forecasting
Aggregate Models Few zones Major highway planning only Computers available to large agencies 50’s Computer chip technology advances Federal government sponsorship Travel behavior surveys widespread Basic transit capability 60’s and 70’s 80’s and 90’s Shift to microcomputers More zones Detailed transit and HOV models Windows-based More disaggregation and detail GIS-based models Microsimulation 00’s
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Why Jurisdictions Convert to TransCAD?
Why are agencies converting their travel models to TransCAD?
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Why Convert? Some widely-used older modeling software are no longer being supported – a new modeling platform is required Limited capabilities in Graphics Memory GIS Network size Number of TAZs
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There are many states in America that currently use TransCAD
TransCAD Users There are many states in America that currently use TransCAD Many states in America are using TransCAD. Some are just beginning, some have full running models. This map is not an exhaustive list.
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Geographic Information Systems
A GIS-based transportation model Compatible with other GIS tools Spatial Analysis ArcView Shape Files TransCAD *.dbd Files
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Why TransCAD? A powerful modeling software that can enhance the modeling process Windows-based menus that are intuitive to manipulate A GIS software with transportation modeling capabilities No internal size limitations Scenario manager for easy file management Ability to easily analyze intermediate results Mapping and visualization tools designed for GIS and transportation applications TIP: Choose a powerful computer!
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The Transportation Model
What is involved with a travel demand model?
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Modeling Process Trip Generation Trip Distribution Mode Analysis
Traffic Assignment Socioeconomic Data Roadway Network Transit Network Transit Ridership Transit Assignment Roadway Volumes Performance Report How many trips? Where will they go? What mode? What route? Identify needs Alternatives analysis Ask the questions…
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TransCAD Inputs Easy to understand file structure
No restrictions on file names, locations, etc. File names are easy to change in the model structure with the scenario manager, created in GISDK Working with TransCAD is very flexible and easy to understand. The scenario manager is a key.
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TransCAD Outputs Checking intermediate modeling results is easy in TransCAD Identifying results from an individual project area allows detailed study of the project Performance module allows consistent reporting of results
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Data and Databases Geographic data Network data Attribute data
TransCAD model data Socioeconomic data US Census data Jurisdictional boundaries Zip codes Railroads Water Features Tiger Streets Files
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AVI – Opens up the Lake Elsinore model dialog box
AVI – Opens up the Lake Elsinore model dialog box. This dialog box runs the entire model from start to finish with one click of the button.
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AVI – An example of a scenario manager
AVI – An example of a scenario manager. This is used to manage all model alternatives with the file names and a few parameters.
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Networks Networks are GIS databases
Conflation to GIS distances and shapes Foundation for traffic counts, performance, transit, and any other data Multi-year network capability TIP: Keep raw count data and adjustments in traffic count database
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Project Selection (TIP/RTP)
Networks GIS Networks Roadway System Transit Routes Air Quality Performance Time of Day Volumes Project Selection (TIP/RTP) Traffic Counts
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AVI – There is a LOT of information stored within the network
AVI – There is a LOT of information stored within the network. This avi shows the info tool and how the user can add data, change data, etc. The network includes a place for Accidents, Bicycle Information, etc.
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AVI – This movie shows two conflation examples as well as a copy/paste example. The thin yellow lines are the city centerline streets, the thick lines are the model roadway network, color coded by facility type (the dotted green lines are centroid connectors). Most jurisdictions have current centerline files, and if not, TIGER files are available for the entire United States.
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Traffic Analysis Zone Data
Zonal areas used in modeling trips Ability to incorporate census data Used for summaries and reports Used for visually verifying data
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Socioeconomic Data Interface with popular GIS platforms
Land use to socioeconomic conversion using TransCAD’s GIS tools Visual representation of land use and socioeconomic data TAZ coverage provides foundation for area- based data and is easily modified TIP: Socioeconomic sub-model can use a Fratar process coded in GISDK
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Socioeconomic Data and TAZ Structure
GIS TAZ Structure Area Type 2020 Socioeconomic Data Performance and Air Quality Area based Indexes K Factors Terminal Penalties 1998 Socioeconomic Data
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AVI – This shows a color map of household density
AVI – This shows a color map of household density. This is useful in verifying and correcting input data.
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Trip Generation Robust cross classification production model
Unlimited trip purposes Production allocation and attraction allocation models TIP: Include all modeling steps in TransCAD using GISDK, without compromising model structure. This ensures a full running model from start to finish.
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Trip Generation Incorporate land use data Detailed trip purposes
Distance-based allocation models Special generators Universities Hospitals Amusement parks Event centers Malls Government installations
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AVI – this shows a dot-density of different land use acreages in Lake Elsinore.
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Trip Distribution TIP: Geocode survey data in house to determine trip lengths Desire lines between TAZs and districts TRIP: GISDK standard gravity evaluation procedure does not correctly apply K factors in version 3.6 Friction factors – calibrated curves versus lookup table
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Mode Analysis Customized nested logit and multinomial logit models
TIP: Don’t be limited to standard TransCAD procedures, create exactly what you want with GISDK Distance-based bike and pedestrian equations
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Nested Logit Structure
Person Trips Motorized Non-Motorized Drive Alone Shared Ride Auto Passenger Transit DA Non Toll DA Toll SR2 Non HOV SR2 HOV SR3 Non HOV SR3 HOV Auto Express Auto Local Walk Express Walk Local Non HOV Non Toll Non HOV Toll Express Urban Rail Commuter Rail Non HOV Non Toll Non HOV Toll HOV Non Toll HOV Toll Express Urban Rail Commuter Rail HOV Non Toll HOV Toll
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Traffic Assignment Time of day User defined volume-delay equations
Speed post-processing Speed feedback AM peak – congested speeds Off peak – freeflow speeds All or nothing, capacity constrained assignments with comparison
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TransCAD Transit Capabilities
Walk access vs drive access Unlimited number of modes Unlimited number of variables Stops dependent upon individual routes
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Transit Assignment Transit boardings by stop, by route, or by mode
Drive or walk access assignment Transit flows by link Transit line volumes
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Validation Screenlines – GIS line layer created quickly
TRIP: One way links confuse the built-in screenline analysis functions
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AVI – This shows a map with volume bandwidth
AVI – This shows a map with volume bandwidth. The movie displays the screenlines.
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Model Conversion Process
Existing Model TRIP: The base converted model is not ready to go! TIP: Develop performance reporting capabilities early. TRIP: TransCAD uses different distances – this may affect model results. TRIP: Need to adjust for software differences. Initial Model Conversion (Caliper or LSA) Network Conflation and Model Replication Performance Reporting Model Enhancements Calibration / Validation
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The endless possibilities with the TransCAD programming language
GIS Developer’s Kit The endless possibilities with the TransCAD programming language
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TransCAD Scripting Capability
GISDK is the TransCAD programming language Allows for complete automation of the modeling process unique to each model Eliminates user error by programming all steps and variables in a model run Similar to programming in C++ (with different syntax and commands) Use the programming editor of your choice to create and edit the GISDK script TIP: Boxer Software is a good (and inexpensive) programming editor GISDK is a very important tool when using TransCAD for running models. With GISDK, everything is programmed to do the exact same thing with the same variables each time it is run. File names can change easily within a scenario manager to create a new model run.
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Model User Interface The dialog boxes that run the whole model
Reduce errors by eliminating point/click/type commands GISDK is the key to programming the model One option to run the model is to go through the menus and use standard TransCAD procedures manually. This can produce many errors and can easily have consistency errors. The best option is to run the model through a dialog box such as this one. Every model run will perform the exact same procedures in the same order with the same parameters! These provide consistency between model users, so more than one person/department can correctly run models.
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TransCAD Dialog Boxes Custom user interfaces created using GISDK
Fully automates the model procedures – including file names, variables, and summary reports TIP: These really help the consistency and accuracy of the model! Dialog boxes created with GISDK allow a user friendly environment to run the models.
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Scenario Manager Created using GISDK
Manages all files related to each alternative An example of the Mason Street model scenario manager. All input and output files are chosen with this dialog box. It uses typical Windows file open and file save as dialog boxes to find the correct files. Since file names can be named in a logical manner, it is easy to find the correct files.
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GIS Developer’s Kit (GISDK)
Program exactly what we want TransCAD to do Allows for any mathematically sound method or procedure Not confined to standard TransCAD procedures Full dialog box customization Scripting allows for full customization.
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Performance Reporting
The possibilities available for performance reporting
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Performance Module Provides consistent and convenient summary reports
Created with GISDK Customized to the client’s needs Analysis tool for troubleshooting model runs Facilitates calibration and validation TIP: Create EARLY in modeling process! A VERY important step!
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Summary Reports The summaries are customized using GISDK and summarize the model data in many ways, including… Facility Type and Area Type Capacity Analysis Congestion Delay Air Quality Emissions Results Summary reports allow the data to be summarized in the same way for each model run. This gives a great comparison tool between several model runs. You can be assured that the reports are summarizing the data in the exact same way – no place for user error.
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Applications TransCAD applications for the transportation planning and analysis process
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Land Use and TAZ Overlay
Land Use Map Land Use and TAZ Overlay TAZ Map
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I-25 Socioeconomic Data Analysis
Land Use Data
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I-25 Corridor Analysis 1998 Data 2020 Data Land Use Data
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Supply and Demand Analysis
Difference
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Colorado Springs Alternatives Analysis
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Buffer Analysis Mile Buffer Travel Time Buffers
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Traffic Impact Analysis
Trip Distribution for a proposed development
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Traffic Impact Analysis
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Site Selection / Geocoding
Fire stations School sites Park locations AVI – This is a geocoding example from Poudre High School. There were no zip codes available in the data, but we can just use the city to locate the addresses. TransCAD is very flexible in the way it geocodes.
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Site Selection / Geocoding
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Travel Sheds / Critical Link Analysis
Identify users of a specific facility Analysis for Adequate Community Facilities Ordinances and road fee programs
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GIS-Based Transportation Improvement Programs
Agency Project Funding Amount Anaheim Lincoln Avenue Signal Coordination $52,910 State College SR-91 $150,000 Buena Park Artesia 1-5 Interchange $132,795 Costa Mesa Fairview Road $29,846 Irvine Bicycle Program $67,200
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Transit Planning and Operations
Strategic transit planning University transportation planning Corridor planning Market identification and productivity Management and placement of capital assets
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Land Use / Transportation / Air Quality
Conceptual level analysis of LUTRAQ relationship Comprehensive plan updates Triggers – population vs. VMT growth Air quality and emissions inventory Stationary and mobile sources On-road mobile emissions estimation Mobile5 Nonattainment area Energy and fuel consumption
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Air Quality Analysis Link-based emissions
Zone-based emissions (i.e. cold starts, evaporate VOCs, etc.) Air quality conformity determinations Redesignation and classification issues Integration with gridded urban airshed modeling Integration with Mobile5
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Land Use / Transportation / Air Quality
Available from the performance summary report for the Fort Collins Nonattainment area
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Integrated Air Quality Modeling
TransCAD Travel Demand Model (speeds, vehicle miles of travel, time of day, …) EPA Mobile/Part Emissions Models (temperatures, fuel characteristics, emission factors, …) Emissions from On-Road Vehicles
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GIS-Based Emissions Inventories
Link-based emissions Gridded Overlay for Region Zone-based emissions
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Intersection Analysis
Intersection Flow Diagram Volumes from TransCAD Traffic Counts NCHRP 255 Process Synchro Intersection Analysis There has always been a concern about getting future intersection levels of service from a link based travel demand forecasting model. We have created an add-in for TransCAD which expedites getting the intersection levels of service into 3d animation. SimTraffic 2D Animation VISSIM 3D Animation
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TransCAD Turn Movement Forecasts
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AVI – a short video with the Turn movements program
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SimTraffic Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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VISSIM Micro-Simulation
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Construction Management
Modify signal timing in response to construction closures
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Future TransCAD Applications
Interactive MPO Project Prioritization and Funding Allocations Traffic Impact Studies: Cumulative improvements and impacts, time of day project distributions FHWA TDM Model Mixed Use Activity Center Trip Generation & Distribution Bicycle Assignments Transportation Corridors Pavement Management
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LSA Associates, Inc. 132 West Mountain Avenue Fort Collins, CO 80524
The ending slide
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Tips, Trips, and Traps of TransCAD Modeling
Presented by LSA Associates, Inc. September 2001 North Carolina MPO Conference Fayetteville, NC
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