Innovations in Travel Demand Modeling, Volume 1: Session Summaries (2008)

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RECENT DEVELOPMENTS WITH THE PRISM- CONSTRAINED ACTIVITY- TRAVEL SIMULATOR AND INTEGRATION WITH THE DYNAMIC EVENT- BASED NETWORK SIMULATOR Ram Pendyala, Ryuichi Kitamura, and Kaira Kikuchi Ram Pendyala discussed recent developments with the Prism- Constrained Activity- Travel Simulator (PCATS) and the integration of PCATS with the Dynamic Event- Based Network Simulator (DEBNetS). He summarized the background to the development of PCATS, recent efforts, and future activities. The following points were covered in his presentation. • There has been rapid progress in activity- based model development over the past decade. The Activity Mobility Simulator (AMOS) was developed with ini- tial funding from the Travel Model Improvement Pro- gram. Components of AMOS include Household Attributes Generation System (HAGS), PCATS, and DEBNetS. In addition, the Florida Activity Mobility Simulator (FAMOS) is the Florida application of AMOS. It represents the calibration of HAGS and PCATS using Florida data. It was tested using area data and networks from southeast Florida. It was funded by the Florida Department of Transportation and completed in 2004. • AMOS includes the household travel survey data, the zonal socioeconomic data, and the network LOS data. All of these data feed into HAGS. HAGS generates a synthetic population of households and persons. All of the elements feed into PCATS, which in turn generates detailed activity- travel records for each person. There is also an output processor, which generates origin–desti- nation matrices by trip purpose, time of day, and mode. A new feature is DEBNetS. • HAGS populates each zone with a synthetic popu- lation of households and persons based on marginal and joint distribution determined by survey data and census data. There are two components to HAGS. One compo- nent is the household distributor that provides the house- hold distributions and attributes. The second component is the fixed- activity generator. This component deter- mines mandatory activities fixed in time and space for each individual. It simulates beginning and ending times of time–space prisms and of fixed activities. There are also multinominal logit models of work and school loca- tion choice. • PCATS is a system of behavioral models that simu- late an individual’s daily activity- travel patterns. The output consists of a series of activity- travel records for each individual. PCATS defines open and blocked peri- ods for each individual. It incorporates modal con- straints related to availability, speed, and captivity. • The structure of PCATS is a series of models to sim- ulate activity- travel patterns. These models include activity- type choice models, joint destination–mode choice models, and split population survival models of activity duration. There are also models by market segment focus- ing on workers, nonworkers, students, and other groups. The origin–destination matrix creator aggregates activity- travel records to create origin–destination matrices by pur- pose, mode, and time of day. It can also be imported into any traffic assignment program. • There are a number of recent developments related to these models and technical tools. One of the major efforts focused on developing an interface and integra- tion with UrbanSim into the OPUS platform. The effort represents a major enterprise. PCATS is also being refined to incorporate quasi- continuous representation of the time–space domain. The model’s interactions among household members are also being enhanced. The integration with DEBNetS is focusing on enhancing the visualization capabilities. There are also plans to inte- grate a pedestrian movement simulator. • The dynamic network simulator considers activi- ties and trips as events that occur in the time–space domain. DEBNetS loads events on the multimodal net- work and dynamically updates paths based on network conditions. Standard speed–flow relationships are used to compute speeds and travel times. Enhancements to the visual displays and animations capabilities are underway. • Integrating PCATS, DEBNetS, and UrbanSim repre- sents an innovative approach in land use and transporta- tion modeling. The OPUS initiative is an international collaboration initiated by Paul Waddell at the University of Washington. It will interface UrbanSim with a host of model systems and analytical and visualization tools. OPUS will create an integrated open source platform with land use and urban systems simulation; activity- based travel models; population, demographic, and economic simulators; and visualization and spatial analysis tools. • These activities focus on linking land use and trans- portation and the use of activity- based measures of accessibility. Activity- based modeling opens new oppor- tunities to integrate long-, medium-, and short- term choices related to residence, work, and school locations, as well as vehicle ownership and fixed and discretionary activity engagement. It also includes destination accessi- bility accounting for time, cost, and reliability. The higher spatial resolution provides improved representa- tion of nonmotorized accessibility. • Work is under way in Japan to introduce a microspatial coordinate system into PCATS. The capa- bility to analyze and microsimulate pedestrian move- 31ACTIVITY-BASED MODELS