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6 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 1
Free market forces respond to the future vision. We need friendly. Universities need to educate more modelers and
to better integrate networks and demographics. MPOs need to ensure competitive salaries for modelers.
From a strategic viewpoint, we need to do a better job Finally, it is important to maintain a focus on who is the
of establishing priorities. We cannot model everything. client of the modeling process. Modeling is not an end in
In some cases, a broader information system may be and of itself. Our job as modelers is to present the model
enough to answer a question without detailed modeling. results to policy makers and the public.
We also need to conduct reasonability checks related to
estimation, calibration, validation, prediction, and
sensitivity. FEDERAL DEMANDS ON
I will highlight a few policy issues and model applica- TRAVEL DEMAND MODELS
tion needs. Land use patterns are changing to include
mixed use and infill development, transit-oriented devel- Edward Weiner
opment, and bicycle- and pedestrian-friendly environ-
ments. Publicprivate partnerships are also more My presentation focuses on the various federal require-
important today. These partnerships relate to both subsi- ments that influence the use of travel demand models,
dies to encourage private development and privatization including provisions of the Safe, Accountable, Flexible,
of toll roads. We also need to be aware of the influence Efficient Transportation Equity Act: A Legacy for Users
of changing technology, including intelligent transporta- (SAFETEA-LU). SAFETEA-LU continues the same basic
tion systems (ITS) to maximize flow and provide infor- transportation planning requirements for MPOs and
mation to drivers, telecommuting, and changing work states. The three basic planning documents that must be
environments and dynamic pricing. We are also seeing developed include a long-range transportation plan, the
more interest in financial constraint issues, emergency transportation improvement program (TIP), and the
preparedness initiatives, and congestion or time-of-day financial plan. The long-range plan and the TIP have to
pricing. be updated every 4 years.
There is interest in time-of-day pricing for a number Numerous options may be considered in these plans
of reasons. For example, the North Central Texas Coun- to address transportation issues in an area. Examples of
cil of Governments has been asked to assess the impact these options include transportation and land use coor-
of increasing peak-period tolls on carpooling, vanpool- dination and new and expanded transportation facilities.
ing, and transit use. We also need to know what the Transportation system management components, trans-
impact is on moving discretionary trips to off-peak peri- portation demand management strategies, ITS, and non-
ods, moving short trips to the frontage roads, and motorized travel may also be considered.
encouraging trip chaining. Other possible impacts relate There are no specific travel demand modeling require-
to increasing flextime hours, work schedule changes, and ments associated with the development of these plans.
telecommuting. Finally, we need to be able to assess However, there are a number of transportation planning
whether increasing peak-period tolls will reduce trip factors that should be considered. These factors include
length over time and increase reliability on the system. supporting economic vitality and increasing safety and
We need to provide policy makers with a list of the security. Other factors address increasing accessibility,
potential impacts and the possible magnitude of these enhancing mobility options, protecting the environment,
impacts. and promoting energy conservation. The consistency
As modelers we do not always do a good job of inter- between transportation and development patterns
preting the model results. We do not spend enough time should also be examined. Additional factors to consider
developing and using performance measures that focus include enhancing integration and connectivity of the
on trip performance rather than link performance. We system, promoting efficient system management and
also need other measures that better address issues of operation, and preserving the existing transportation
interest to policy makers and the public. Performance system.
measures that focus on multimodal user benefits, envi- There are two basic environmental requirements
ronmental justice, accessibility by mode, and trip-time related to the transportation planning process and the
reliability are needed. Other measures that address project development process. The first requirement
crashes, injuries, and fatalities by mode, as well as fuel relates to the National Environmental Policy Act (NEPA)
consumption would also be of benefit. and the second addresses transportation air quality con-
In conclusion, it is important that we continue to formity analysis. NEPA requires an estimate of environ-
maintain an objective technical process. We need to tran- mental impacts and an evaluation of land development
sition from existing models to better models. We need to effects of new highways. Mitigation strategies must be
do a better job of training and documenting these new developed and implemented if there are any negative
models. It is also important to keep the new models user impacts. An air quality conformity analysis that meets
