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OCR for page 189
178 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 2 3. Effects of transportation system and system Air quality: As always, evaluation of the effects on condition; air quality of various policy and transportation initia- 4. Need for improved validity and reliability; tives will continue to be a key issue in regional planning. 5. Ability to evaluate policy initiatives; Highway project planning: This also will continue 6. Better analysis of freight movement; to be a core focus of the planning process in the region. 7. Ability to show environmental effects; 8. Modeling low-share alternatives; 9. Better ability to evaluate effects on specific sub- ACTIVITY-BASED MODELING APPROACH groups; and 10. Reflect nonsystem policy changes (TDM, ITS). In addition to providing guidance concerning the needs that a new model must address, the vision phase vali- dated DRCOG planners' initial impression that an HIGH-INTEREST POLICY ISSUES activity-based modeling approach would best meet those planning analysis needs for the region. While it is These issues were boiled down in the vision process to clear that activity-based modeling as it can be imple- keep the list short. More specific, high-interest policy mented now cannot fully address all of the issues dis- issues in the Denver region include: cussed above, it is superior to conventional four-step modeling in many respects. DRCOG and its consultant The Colorado Tolling Enterprise (CTE): Estab- team have concluded detailed design of an activity- lished 2 years ago by the state legislature, the CTE has based model, considering the region's planning needs been working to identify a set of corridors with the and resource constraints, and model development is potential for toll facility establishment. The CTE has now in progress. identified about six such corridors in the Denver area The activity-based modeling approach chosen by and is conducting an evaluation of these corridors, which DRCOG is based on that used in the model developed is expected to be submitted to the regional planning for the San Francisco County Transportation Authority process for inclusion in the regional plan. These efforts in 20002001, but includes enhancements informed by also have caused planners conducting several environ- the capabilities of some of the activity-based models mental impact statements in the region to take a harder implemented more recently in other areas. The approach look at toll options in their alternatives' analyses. includes microsimulating the daily activity patterns of The effects of MetroVision urban centers and other individuals in a synthetic population; determination of transit-oriented developments: Support of such develop- "regular" workplaces and school locations in relation to ment patterns is intended to foster a more balanced the home location; the modeling of the times of day, des- transportation system, reduce the number and lengths of tinations, and modes of tours and trips; and the use of trips, foster additional bicycle and pedestrian use, and so conventional static highway and transit assignment pro- forth. The MetroVision 2030 update developed in 2004 cedures. The model design is described more completely included approximately 70 such centers, and the evalua- by Cambridge Systematics, Inc., et al. (1). tion of the effects of these centers is a key aspect of the In general, the activity-based modeling approach regional model's usefulness. These will be evaluated would be expected to produce more accurate results for again during the MetroVision 2035 process. policy testing because it can consider a wider range of Effects of the MetroVision urban growth bound- variables and interactions than a conventional trip-based ary: The extent of the urban growth boundary or area model. Trip-based models tend to be relatively insensitive currently is set at approximately 750 sq mi for the year to many input data changes (such as transit-oriented, 2030, and the extent to which it may need to be development-related land use changes) because they usu- expanded for 2035 will be a key part of the MetroVision ally do not include enough detail (geographic location, 2035 process. demographic variables, triptour relationships, and so Reexamination of lower-density development, forth) to permit them to respond fully to such changes. referred to as semi-urban: Issues include defining semi- Trip-based model users often resort to adjustment factors urban, estimating how much of it there is, how much to account for behavior that cannot be analyzed by these should there be, and its transportation and air quality models, with varying degrees of reliability and success; effects. activity- and tour-based models are expected to provide The FasTracks ballot initiative of 2004: Passage of considerably improved forecasting for all types of policy this initiative kicked off a project to build about 130 mi analyses. Of course, the level of increased accuracy may of rapid transit to all parts of the region by 2017. The depend on how much the analysis of the specific policy ability to evaluate the effects of such a system will be depends on the factors that are considered in the activity- critical over the next decade. based approach but not in the trip-based approach.