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decennial census in 1990. In 2002, the modelâs data were already 10 years old and needed to be updated using new socioeconomic data based on the 2000 census. Also, adjustments needed to reflect the impact of September 11, 2001, on employment and labor force data. Because of insufficient funding, the Regional Travel Household Interview Survey, which was conducted in 1997 and 1998, did not include the survey of establish- ments as travel generator or attraction points, so tourist trips were ignored. Modeling Issues ⢠Needs for different level of details of modeling doc- umentation not addressed properly. ⢠Gap between availability of proper documentation and completion of the models. ⢠Lack of full integration of transit and highway networks. ⢠Lack of integration of land use model and travel demand model in the NYBPM system. ⢠Long processing time. Modeling Environment ⢠Diversity of the large region: NYBPM is the first regional model of its geographic and functional scope ever implemented successfully in such a large metropoli- tan region. The New York metropolitan area is unique because of its complex transportation system, diverse population and area type, and its size in both population and area. This diversity adds to the complexity of travel analysis. ⢠Software issue: It has been a challenge to address the compatibility issues of various NYBPM software ver- sions with various versions of TransCAD as NYBPMâs platform. TransCAD is used to manage, edit, and mod- ify the NYBPM transportation highway and transit net- work databases, and for path building and the development of âskim- treeâ matrices of travel times and costs used in the choice models. NYMTC faced some compatibility issues because different member agencies used different versions of TransCAD. Also, compatibility among other software packages used with NYBPM was a problem. ⢠Hardware issue: The application of the NYBPM model requires an extensive amount of computational resources, as well as careful management of a large num- ber of computer files. Running NYBPM requires a set of special hardware specifications, including dual proces- sors, which could provide an efficient computing appli- cation system for NYBPM. USER TRAINING One of the daunting tasks facing NYMTCâs modeling staff is to provide training to stakeholders who are inter- ested in various NYBPM applications. The stakeholders, based on the levels of technical knowledge and special needs for their applications, require different levels of training, and NYMTC has developed training programs to meet those needs. One- day training is provided to the decision makers; 3- to 5-day training has been developed for individuals who have some modeling background; and a one- to- one training spanning several weeks is being provided to staff of member agencies that need to run the model for specific project analyses. STAFF RESOURCES Staffing has been a key issue in NYMTCâs model imple- mentation process. Several reasons that attributed to this issue are identified below. Lack of Trained and Experienced Modeling Staff There is an inherent shortage of experienced modelers in this country. NYMTC staff, with limited experience at the beginning of the process, needs to work with the stakeholders and the consultants in developing and implementing the complex modeling system. At the same time, NYMTC staff needs to learn all the aspects of model development, including data collection, model methodology, model estimation, calibration and valida- tion, and applications, including project coding, model output analysis, and quality control. High Turnover Rate NYMTC also faces the problem of retaining qualified individuals because of organizational constraints. Because NYMTC is hosted by New York State Department of Transportation (NYSDOT)âthat is, NYMTC is not a separate legal entityâ it must abide by NYSDOTâs rules for promotional opportunities. Promotions in NYSDOT are based on examinations that are not closely related to the modeling work, which puts the modelers at a disad- vantage for career advancement within the organization. Hiring Constraints Hiring in NYMTC is an ongoing struggle. NYMTCâs modeling group has lost several staff members over the 174 INNOVATIONS IN TRAVEL DEMAND MODELING, VOLUME 2