NCHRP Project 08-36
Proposed Research Problem Statement
1. Title State DOT Practices for Estimating Transportation Impacts of Non-Traditional
Developments
2. Background
State DOTs work with localities in the land development process relating to mixed-use, infill,
transit oriented, urban and smart growth (MITUS) developments that impact state highways. Traditional
trip generation rates developed by the Institute of Transportation Engineers (ITE) for mostly single-use
suburban conditions are not applicable to MITUS developments, and their use results in incorrect
estimations of the number of automobile trips that MITUS developments are expected to generate.
The Virginia General Assembly required the Virginia Department of Transportation (VDOT)at
all times after July 1, 2011, to “have at least one non-ITE [Institute of Traffic Engineers] trip generation
methodology or alternative rate approved for preparing SAP [Small Area Plan] traffic impact statements”
(24 VAC 30-155-60 D.2). Based on a review of six potentially applicable methods, the Virginia Center
for Transportation Innovation and Research (VCTIR) recommended that VDOT use the U.S.
Environmental Protection Agency’s Trip Generation Tool for Mixed-Use Developments as the non-ITE
methodology required. However, this was a “stop-gap” solution as all available alternatives have
shortcomings. VDOT continues considering ways in which the issue could be addressed more
comprehensively.
3. Statement of Urgency
Although a few alternative (to ITE) methods have recently been developed, they have narrow
applicability, since the number of on-site features and context variables that were considered are limited.
In other words, there is a broad range of non-traditional development conditions for which trip generation
methods are not available. Also, available alternative methods and related information are not easily
found.
In the absence of accepted national practices, public (state and local departments of transportation
and metropolitan planning organizations) and private sector practitioners (developers, planners, and
engineers) are struggling on a case-by-case basis to estimate the transportation impact of MITUS
development proposals. If the impacts are underestimated, it may lead to under-investment in necessary
infrastructure. If the impacts are overestimated, it may lead to additional investor costs, e.g., excess
parking, excessive impact and other development fees, and investment in the wrong kind of infrastructure.
4. Project Objective
The objective of this project is to review and evaluate state DOT practices for estimating
transportation impacts of non-traditional developments, such as mixed-use, infill, transit-oriented, urban,
and smart growth (MITUS) developments.
5. Relationship to Existing Body of Knowledge
ITE, researchers and practitioners recognize that traditional ITE trip generation rates are not
applicable to MITUS developments. (Arrington and Cervero, 2008; HNTB Corporation, 2009; KimleyHorn and Associates, Inc., 2009; ITE, 2008; Litman, 2010 and Walters et al. 2010). In Volume 1 of Trip
Generation, ITE (2008) advises users to consider modifying ITE trip generation rates for local conditions
that are different than the conditions of the sites where ITE data were collected.
Recently developed alternative methods along with ITE’s method for estimating internal capture
rate were reviewed by a research team at the Sustainable Transportation Institute at the University of
California, Davis (Lee et al., 2011). The team evaluated five methods: (1) NCHRP 08-51; (2) ITE’s
multi-use; (3) Metropolitan Transportation Commission survey-based method; (4) Urbemis
(Nelson/Nygaard, 2005); and (5) the EPA-MXD. Lee et al. (2001) found no clear “winner” among the
five methods based on operational criteria or accuracy. NCHRP 08-66 is underway to develop tripgeneration rates for infill developments. Most methods lack validation.
6. List of Anticipated Work Tasks



Identify existing state laws that address the transportation impact of MITUS developments.
Identify alternative methods, alternative to the traditional ITE methods, that are approved or
provided by state DOTs to forecast the transportation impact of MITUS developments.
Describe current practices of state DOTs dealing with the transportation impact of MITUS
developments.

Develop recommendations for what method to apply for what kind of MITUS land
development projects and

Identify gaps where further methods are needed to support estimating transportation impacts
of non-traditional developments.
7. Estimate of Funds Needed:$75,000
8. Estimate of Time Needed to Complete the Research: 1 year including preparation and
review of final report
9. Name, Affiliation and Contact Information of Submitter(s)
Ilona O. Kastenhofer, Senior Research Scientist, Virginia Department of Transportation,
Virginia Center for Transportation Innovation and Research, 530, Edgemont Road,
Charlottesville, VA, 22903; phone: 434-293-1981, e-mail:
ilona.kastenhofer@vdot.virginia.gov; submitted in my capacity as a member of TRB
Committee ADD30- Transportation and Land Development and as a state DOT researcher.
The Problem Statement benefited from review comments provided by members of the
Transportation and Land Development Committee.
10. Date of Submittal: April 2, 2012
References:
Arrington, G.B., and Cervero, R. Effects of TOD on Housing, Parking, and Travel. TCRP Report 128.
Transportation Research Board, Washington, D.C., 2009.
HNTB Corporation. Alternative Mode (Non-Auto), Final Report, Trip Reductions Database Study.
Virginia Department of Transportation, Chantilly, 2009.
Institute of Transportation Engineers. Trip Generation, 8th Edition: An ITE Informational Report.
Washington, DC, 2008.
Kimley-Horn and Associates, Inc. Trip-Generation Rates for Urban Infill Land Uses in California Phase
2: Data Collection, 2009.
http://www.dot.ca.gov/research/researchreports/reports/2009/final_summary_reportcalif._infill_trip-generation_rates_study_july_2009.pdf. Accessed December 15, 2011.
Lee, R., Miller, J., Maiss, R. Campbell, M., Shafizadeh, K., Niemeier, D., Handy, S., and Parker, T.
Evaluation of the Operation and Accuracy of Five Available Smart Growth Trip Generation
Methodologies. University of California, Davis, 2011.
Litman, T. Land Use Impacts on Transport. Victoria Transportation Policy Institute. Victoria, British
Columbia. 2010.
Metropolitan Transportation Commission. Planning: Station Area Residents Survey, 2006.
http://www.mtc.ca.gov/planning/smart_growth/stars/. Accessed December 15, 2011.
Nelson\ Nygaard Consulting Associates. Crediting Low-Traffic Developments, Adjusting SiteLevel Vehicle Trip Generation Using URBEMIS. San Francisco, 2005.
Transportation Research Board. NCHRP 08-51 [Completed]. Enhancing Internal
Trip Capture Estimation for Mixed-Use Developments. Washington, DC, 2011a.
http://apps.trb.org/cmsfeed/trbnetprojectdisplay.asp?projectid=927. Accessed December 11,
2011.
Transportation Research Board. NCHRP 08-66 [Active]. Trip-Generation Rates
for Transportation Impact Analyses of Infill Developments. Washington, DC, 2011b.
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=1616. Accessed October 5,
2011.
U.S. Environmental Protection Agency. Smart Growth: Trip Generation Tool for Mixed-Use
Developments, 2011.
http://www.epa.gov/smartgrowth/mxd_tripgeneration.html. Accessed October 5, 2011.
Walters, J., Lee, R., Feldman, M., Gray, C., Levasseur, L., Watten, M., Ruehr, E., and Singleton, M. Trip
Generation for Smart Growth. San Diego Association of Governments, San Diego, CA, 2010.
http://www.sandag.org/uploads/publicationid/publicationid_1500_11604.pdf. Accessed
December 20, 2011.