Travel and land-use forecasts play an important role in informing the purpose of and need for large-scale transportation and infrastructure projects by providing useful projections for project managers and decision makers. Forecasting encompasses several parts of the National Environmental Policy Act (NEPA) process, including analysis of alternatives, estimation of
environmental impacts and emissions, and assessment of future land-development and cumulative effects. While
transportation organizations have produced several technical guidance documents on travel and land-use forecasting, there
is little guidance on process considerations that explain how to apply forecasting in the context of NEPA. Such
considerations are important because the process is often debated among agencies and interest groups. The Federal
Highway Administration (FHWA) has addressed this need through the publication Interim Guidance on the Application of
Travel and Land Use Forecasting in NEPA (the guidance) issued in April 2010. This issue of Successes in Stewardship
describes the background and content of the guidance and provides applications for transportation practitioners.
The guidance encourages NEPA managers, FHWA staff, Metropolitan Planning Organizations (MPOs), and State
Departments of Transportation to follow a multistep process when conducting forecasts for NEPA (see sidebar). As
forecasting strategies will vary depending upon project type, scale, and location, the steps in the guidance were designed to
be flexible and scalable to improve the accuracy and consistency of forecasting across project types.
FHWA based the guidance on the ideas and experience of experts in the field, attorneys, and other stakeholders, with the
intention of sharing forecasting shortfalls that consistently arise during the NEPA process. Attorneys helped FHWA to select
guidance considerations that demonstrate current judicial perspectives on the NEPA process. Forecasting is not a
regulated process and the guidance will not be mandatory. However, FHWA expects that the guidance will result in more
engagement and communication among practitioners and will reduce litigation.
- Assessment of project conditions
and scoping of study's forecasting
- Review of suitability of modeling
methods, tools, and underlying data.
- Scoping and collaboration on
- Objective application of forecasting
- Project-management considerations
- Forecasting for noise and airemissions
- Documentation and archiving
The guidance explains seven key considerations of forecasting that can be
categorized into three areas: project set-up, alternatives analysis, and project
Overview of the Guidance Process
The guidance recommends that project managers assess forecasting
methodologies, collaborative efforts, and project scope at the beginning of
each project. This initial step will ensure that there is sufficient coordination
with other projects and agencies and that current best practices and
technologies in forecasting are used. Project managers should carefully select
forecasting tools based on geographic scales, and the project team should
agree upon the timeframe of analysis. In addition, the guidance emphasizes
the benefits of keeping detailed records during this initial phase. Proper project
set-up, including initial documentation, can decrease the likelihood of project
litigation and the probability that forecasting will need to be repeated.
The guidance emphasizes the importance of unbiased forecasting when
analyzing each alternative. Project managers should be aware of the
assumptions in the forecasting model and the uncertainties in a forecast. They
should also verify model inputs and data from other sources so that one
alternative does not appear to be favored. Both direct and indirect effects of
transportation and land-development investments should be considered for each alternative. Improper analysis of
alternatives can lead to litigation or to the need to recreate a forecast.
The guidance calls upon practitioners to thoroughly and accurately document assumptions, data sources and files, and
decisions throughout the forecasting process. Project managers should document forecast methodology so that forecasts
are repeatable by project sponsors in the future. They should also save and distribute files to project sponsors so that
sponsors can make changes or input data updates. The forecasting process may be misinterpreted if the project team does
not document decision rationales or stakeholder involvement.
Case Study: Mountain View Corridor, Utah
Development in Salt Lake County: Pre-1970 near downtown (green), 1970-1989 (yellow), and post-1990
(red). (Graphic courtesy of Utah Department of
The guidance includes four case studies that demonstrate the use of the
forecasting considerations. One of these cases is Mountain View Corridor in
Salt Lake County, Utah. The corridor comprises a 35-mile freeway, a 20-mile
transit system, and a trail adjacent to the freeway in western Salt Lake and
northwestern Utah Counties. The case highlights three steps in the guidance
process: scoping and collaborating on methodologies, forecasting in the
alternatives analysis, and taking project-management considerations into
account. The project emphasizes a reduction in roadway congestion as well as
increases in mobility, local growth, and trail use.
During the project, land-use development and travel-demand modeling
incorporated early stakeholder involvement at the stage of project scoping and
model updates. Regional MPOs collaborated with a nonprofit group, which
completed a peer review of corridor projects. The model included an analysis
of the sequence of roadway and transit improvements as well as an analysis
of the alternatives and documentation of land-development impacts. There
were several reevaluations of the analyses and model, and of the consistency
of data collection from planning documents, as well as frequent team
communication and meetings.
FHWA held three webinars in April and May of 2010 to clarify the main points
of the guidance and to provide additional information to practitioners. FHWA
plans to hold State-specific workshops throughout the remainder of
the year, focusing on contexts, precedents, and forecasting considerations
(contact Michael Culp for workshop details).
The guidance has been in effect as of its release on April 12, 2010. FHWA will accept feedback on the guidance through September 30, 2010, and will issue a final guidance report once the update is complete. Comments or questions should be
sent to Michael Culp (see contact information below). FHWA has also provided a website for Frequently Asked Questions
about the release, content, and next steps for the guidance.