Office of Planning, Environment, & Realty (HEP)
For a number of metropolitan planning organizations (MPOs) and other planning agencies aspiring to advance their demographic forecasting process, the means of attaining and implementing enhanced demographic forecasting procedures is not readily apparent. As one e-mail list respondent noted, "…the migration path from DRAM/EMPAL (a widely used land use model) to state of the practice, if not art, is not clear to me". Other e-mail list respondents noted some trepidation in utilizing more advanced land use models even though it may be well documented and not overly complex. These concerns led to discussions on the merit of implementing advanced land use software packages and the investment of resources required to adequately implement land use models. The following is a brief synopsis of contributions to the e-mail list regarding the rationale for implementing advanced land use models, the means of doing so, and some concluding cautionary remarks.
E-mail list respondents offered several reasons and observations for wanting to implement more sophisticated land use models as well as the practicality of implementing newer models. These reasons included perceived limitations of traditional land use models and the potential benefits derived from implementing newer models.
Respondents cited the following limitations of traditional land use models:
The following comments were offered as a potential motivation, or improvements that could be realized, by implementing advanced land use models:
As noted by several contributors, transitioning from traditional land use models to more advanced models can be accomplished through incremental steps or stages. Moreover, the migration process need not merely represent a perfunctory change from one software platform to another platform. The following is a suggested approach for transitioning to a more robust land use model:
The use of local data sources and initially simplifying the land use model as much as possible was also viewed as a useful means of transitioning from traditional models to more advanced models. Having capable staff that thoroughly understands both the intricacies of the land use model as well as local real estate markets was seen by one respondent as being imperative in successfully transitioning to a more advanced land use model.
Similar to other efforts aimed at implementing advanced modeling methodologies, the land use modeling community does not have a standard model or process from which to draw upon. There are currently several different models and methodologies available for application. One e-mail list respondent noted that the modeling community should develop methods for providing, at a minimum, acceptable practice methodologies that are accessible and straightforward. An acceptable practice threshold was defined as a set of models that included feedback from transportation to land use and enough sensitivity to policies such that it made model application advantageous for MPOs. This was viewed as an inception point from which incremental improvements could be implemented over time with the ability to assess each enhancement from a cost benefit perspective. To achieve this however, it was noted that flexible and modular software platforms that allow incremental improvements first need to be developed.
One respondent stated that the implementation of advanced models will require a commitment to assemble the necessary data, as well as calibrating and properly applying the model. Other concerns regarding the implementation of advanced models included the following:
Despite these concerns it appears that a number of agencies conclude that the regional planning process will benefit from an integrated land use and transportation model.
There is a strong interest within the modeling community to move forward and begin implementing more sophisticated land use models that may have the capability to more accurately depict the potential impacts of policy-level decisions. The current perception is traditional land use models have limited capabilities and are not sensitive to locally proposed policy initiatives. In response to concerns regarding the efficacy of transitioning to more advanced land use models, several respondents outlined a variety of steps that can facilitate the actual transition. Final considerations for those planning to implement more advanced land use models include the decision whether to use open source or commercial vendor software, the process for choosing appropriate software, whether to customize the software and to assess the trade-offs of being an early adopter of advanced methodologies.
The objective of the series is to provide technical syntheses of current discussion topics generating significant interest on the TMIP e-mail list. Each synthesis is drawn from e-mails posted to the TMIP email list regarding a specific topic. The syntheses are intended to capture and organize worthwhile thoughts and discussions into one concise document. They do not represent the opinions of FHWA and do not constitute an endorsement, recommendation or specification by FHWA. These syntheses do not determine or advocate a policy decision/directive or make specific recommendations regarding future research initiatives. The syntheses are based solely on comments posted to the e-mail list.