2.2 Software Requirements
The model system components are currently configured to run under a variety of Windows versions, including Windows Server 2008 and Windows 7 and more recent updates.
Cube Voyager is a commercially available software package developed by Citilabs, Inc. for the modeling and analysis of regional passenger transportation systems including roadways, public transit, pedestrians and bicycles. Cube Voyager uses a modular and script-based structure allowing the incorporation of any model methodology ranging from standard four-step models, to discrete choice to activity-based approaches. The software also includes highly flexible network and matrix calculators for the calculation of travel demand and for the detailed comparison of scenarios.
Models built with Cube Voyager can take many forms:
- Four-step models commonly used in urban areas: Cube Voyager includes easy-to-use templates for developing generation, distribution, mode choice and assignment structures
- Activity-based demand: Cube Voyager provides the flexibility to incorporate most of these techniques. It is simple to incorporate specifically designed modules for the analysis and estimation of activity patterns. (eg. the NERPM-AB model system)
- Combined equilibrium models: Cube Voyager provides a complete scripting and equilibrium feedback language allowing models of this form to be implemented.
Past regional travel model systems employed in the region have relied on and made use of the Cube Voyager software. In the new NERPM-AB model many elements of that previous framework are retained since the software and data structures used to represent the supply-side component of the overall model system are unchanged.
Role in the Model System
Cube Voyager serves three (3) important functions in the NERPM-AB model system.
- The software is used to open, view and execute the Cube model catalog file (NERPMAB2.cat) and therefore represents the graphical user interface (GUI) for the entire regional travel model.
- The software includes a built-in Scenario Manager allowing users to modify elements of any desired scenario: defined alternatives (eg. analysis years), applications executed as part of the scenario, the list of data inputs/outputs, and the catalog key parameter values that affect and define different scenarios.
- The software also and most importantly controls the overall model system flow based on the execution of certain model steps in a prescribed sequence using built-in algorithms and user-specified scripts that specify inputs, parameter values and outputs. In addition, the software in the case of NERPM-AB includes the integration between the DaySim activity-based demand model and Cube Voyager supply model where DaySim is called from within the Cube 6 runtime environment.
FDOT has relied on Cube Voyager for previous regional planning models and so these concepts and this regional planning and forecasting software should be familiar to most end-users already practicing in the region.
The travel demand model used in the Northeast regional planning activity-based model system is coded in a software framework called DaySim. DaySim is one of the two main “families” of activity-based model (AB) systems now being used by MPOs in the United States. DaySim was initially implemented by Mark Bradley and John Bowman in Sacramento, CA, on behalf of the Sacramento Area Council of Governments (SACOG).
DaySim simulates 24-hour itineraries for individuals with spatial resolution as fine as individual parcels and temporal resolution as fine as single minutes, so it can generate outputs at the level of resolution required as input to dynamic traffic simulation. DaySim’s predictions in all dimensions (activity and travel generation, tours and trip-chaining, destinations, modes, and timing) are sensitive to travel times and costs that vary by mode, origin–destination (OD) path, and time of day, so it can, in turn, effectively use as inputs the improved network travel costs and times output from a dynamic traffic simulator. DaySim captures the effects of travel time and cost upon activity and travel choices in a way that is balanced across modes and times of day and consistent with the econometric theory of nested choice models.
The C# (C-sharp) version is used for the NERPM-AB model system, and can be compiled to run in both 32- and 64-bit environments. DaySim can be used in a distributed manner by running separate instances on different processors on different partitions of the study area population, and then merging the results.
Role in the Model System
The DaySim activity-based demand model produces six principal outputs: 1) Household file, 2) Household day file, 3) Person file, 4) Person day file, 5) Tour file and 6) Trip file. Taken together, these hierarchical output files are similar to the data files from a traditional household travel diary survey. In this case, however, instead of actual trips from a subsample of the actual population, DaySim produces simulated daily trips for an entire, synthetically generated population of travelers.
No complex installation of the DaySim software is required. DaySim simply resides as a single compiled executable within the NFTPO model directory structure. The compiled executable (DaySim.exe) can be found in the \User.prg\DaySim subdirectory.
R is a language and environment for statistical computing and graphics. R provides a wide variety of statistical and graphical techniques, and is highly extensible. One of R's strengths is the ease with which well-designed publication-quality plots can be produced, including mathematical symbols and formula where needed.
R is open-source available as Free Software under the terms of the Free Software Foundation's GNU General Public License in source code form. It compiles and runs on a wide variety of UNIX platforms and similar systems (including FreeBSD and Linux), Windows and MacOS.
R is an integrated suite of software facilities for data manipulation, calculation and graphical display. It includes:
- An effective data handling and storage facility,
- A suite of operators for calculations on arrays, in particular matrices,
- A large, coherent, integrated collection of intermediate tools for data analysis,
- Graphical facilities for data analysis and display either on-screen or on hardcopy, and
- A well-developed, simple and effective programming language that includes conditionals, loops, user-defined recursive functions and input and output facilities.
More information on R can be found at: http://www.r-project.org/.
Role in the Model System
R is not actively used in this model. R is supplied with the model to generate DaySim summaries for calibration and validation.
Once DaySim is run and day patterns of all the persons in the model system have been simulated, R-scripts are also used to prepare summaries of various sub-models outputs such as auto ownership, tour/trip modes and times, etc. Summary tables are written out to Excel spreadsheets that are subsequently used calibration and validation of the AB demand model.
No complex installation of the R software is required. R simply resides as a single compiled executable within the NFTPO model directory structure. The R application can be found in the \R-3.4.4 subdirectory.
PopulationSim is an open platform for population synthesis and survey weighting. It is a Python-based tool for population synthesis which includes an easy-to-use interface. More information on PopulationSim can be found at the ActivitySim website: https://activitysim.github.io/populationsim/index.html
Role in the Model System
Activity Based Models (ABMs) operate in a micro-simulation framework, wherein the travel choices of person and household decision-making agents are predicted by applying Monte Carlo methods to behavioral models. This requires a data set of households and persons representing the entire population in the modeling region. Population synthesis refers to the process used to create this data.
PopulationSim required 64-bit Anaconda (Python 2). No complex installation of the Anaconda software is required. Anaconda simply resides in \User.prg\Population_Synthesis\Anaconda2 within the NFTPO model directory structure. Anaconda is an open-source distribution of Python which bundles the most useful python libraries together for making it easy for the users.
The developers of PopulationSim have created a detailed stand-alone wiki which provides clear instructions, steps and visual cues to walk a new user through the installation or update of both the supplementary software and PopulationSim. The wiki also describes how to use the software, how to validate model results and also describes how PopulationSim works in detail.