Planning & Travel Demand with TransCAD

Fully-Windows Compliant: TransCAD is the only package that is fully Windows compliant and supports Windows standards like .NET, ADO, data exchange with Office, and the full complement of user interface conventions.

Outstanding Graphics: TransCAD has the best graphics of any planning software ever produced. TransCAD provides high quality map output with dozens of thematic mapping styles and options, unlimited colors, fully scalable line styles and TrueType map symbols, and a complete set of freehand drawing and annotation tools.

There is automatic display of one-way streets, labels that adjust to the map scale, and built-in highway shields. There are specialized displays for flow maps, transit route systems, and multi-modal desire lines. There are also pie, line, and bar charts, intersection diagrams, and strip charts based upon linear referencing. Page layout tools let you combine any number of maps, charts, data tables, and matrices in a single presentation.

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 software. As a result, to do your work with other packages requires that you master the operation of four or five programs instead of one. Also, with TransCAD, you don’t need to spend all of your time importing and exporting files.

Comprehensive Modeling Procedures: TransCAD has the most comprehensive set of models and Caliper has the goal of providing a superset of the modeling tools available in any package. Consequently, TransCAD has many more useful procedures and alternatives for doing your work.

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. These capabilities extend to areas larger than regions bringing integrated modeling capabilities for passengers and freight to statewide, national, and international geographic scales.

Powerful Built-in Database: TransCAD includes a powerful relational database and can work with data in all manner of external databases. TransCAD can work directly with Access, Oracle, and Oracle Spatial, and is ODBC compliant so it can work with data in any database for which OBDC drivers are available, such as SQL Server.

The Most Powerful Matrix Engine and Virtually Unlimited Modeling Capacity: TransCAD was designed to enable very large models to be implemented. 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. In fact, TransCAD performs matrix computations with incredible speed. For these reasons, TransCAD is being used in many large metropolitan areas including New York, Los Angeles, Denver, and Dallas-Ft. Worth.

Highest Quality Documentation: There are many other respects in which TransCAD sets a new standard for demand forecasting software such as ease of use and data access, highest quality documentation, and flexible programmability. TransCAD documentation includes a comprehensive travel demand modeling manual 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 systems 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 systems.

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
The 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.

An 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

Public 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.