NCHRP 08-36: Research for The AASHTO Standing Committee on Planning
2009-07
(NOTE: This project is being presented to the 08-36 Panel for their comments and possible endorsement. CalTrans intends to submit it as a full NCHRP project)
I. Problem Number (to be assigned by NCHRP staff)
II. Problem Title:
III. RESEARCH PROBLEM STATEMENT
The National Environmental Quality Act (NEPA) and other State, Federal, and local laws and ordinances require that proposed land-use development projects be analyzed regarding their potential transportation and related effects. A recent study funded by the California Department of
Transportation (Caltrans)
1
found that there are significant limitations in the capabilities of data and analytical models that have been used for many years to assess site-specific land-use development projects with “smart growth” characteristics, such as: urban infill, pedestrian and transit-oriented, and mixed land-use developments.
This study also found that existing standard methods of estimating trip generation, parking demand, and travel modes associated with land-use projects are based on data that is obtained at single-use suburban locations that lack public transit or good pedestrian access.
2
Therefore, these methods are currently not able to accurately assess benefits, estimate impacts, size infrastructure, develop appropriate mitigations, or create incentives regarding proposed smart growth land-use projects.
Development of a software-based analysis tool that can be used to more accurately assess proposed land-use projects that have smart growth attributes or are located within existing urban infill areas would be extremely useful to local cities, counties, regions, States, developers, and community groups in implementing state, regional, and local plans, programs, and projects.
IV. LITERATURE SEARCH SUMMARY
California efforts:
Several efforts are underway to develop data that could be used in an analytical tool. The California
Department of Transportation (Caltrans) is currently funding an effort to develop and disseminate trip generation rates for land-uses located in California’s urban infill areas. In close coordination with an expert technical advisory group, this study has made significant progress in defining a methodology for collecting and reporting more accurate infill trip generation rates data.
3 A second phase of this study is underway that will produce actual infill trip rates data . Other directly related Caltrans-funded research projects include:
”Assessment of Local Models and Tools for Analyzing Smart-Growth Strategies”
and
“Assessment of Transit-Oriented Development & Household Travel” 2006 - UCLA.
National research:
1
”Assessment of Local Models and Tools for Analyzing Smart-Growth Strategies”
– DKS & professors at UCs
Irvine & Santa Barbara, July 2007. http://www.dot.ca.gov/newtech/researchreports/reports/2007/local_models_tools.pdf
2
Trip Generation Handbook Second Edition, Institute of Transportation Engineers, Washington D.C., 2004.
3 “ Trip Generation Rates for Urban Infill Land-uses in California – Phase 1: Data Collection Methodology and
Pilot Application” Kimley-Horn Associates, EPS & ABAG, April 2008 (for Caltrans). Available at: http://www.dot.ca.gov/newtech/researchreports/reports/2008/ca_infill_trip_rates-phase_1_final_report_appendices_4-24-08.pdf
1 of 3

NCHRP Project 08-66
“Trip-Generation Rates for Transportation Impact Analyses of Infill
Developments” is also currently underway to develop infill trip generation rates data nationally.
Another closely related study, NCHRP Project #8-51 -
“Enhancing Internal Trip Capture Estimation for Mixed-Use Developments” - provided updated internal travel "capture" rates for mixed land-uses.
TCRP Project H-27A
“Ensuring Full Potential Ridership from Transit-Oriented Development” recently produced trip generation rates data for a number of transit-oriented developments throughout the U.S. In addition, an effort funded by U.S. EPA is currently underway that will provide important data for this project, is entitled: "Mixed-use Development and Vehicle Trips: Improving the Standard
Estimation Methodology" (under EPA’s Smart Growth Mission Contract).
V. RESEARCH OBJECTIVE
This project will produce a computerized analysis tool for use in site-specific traffic impact and environmental analyses of proposed land-use projects that have smart growth attributes, such as: urban infill, pedestrian and transit-oriented, and mixed land-use developments. The need for an analysis tool that can more accurately assess traffic impacts and multi-modal travel associated with smart growth land-use projects has long been recognized. However, until recently there has not been sufficient data available for developing such a tool possible.
Building on data from recent and ongoing research (listed in Literature Search Summary), this Project will develop a new deployable analysis tool (that currently does not exist) that cities, counties, consultants, project proponents, community groups, and others can use to more accurately estimate the quantities and modes of travel associated with a variety of proposed smart growth land-use projects.
VI. – ESTIMATE OF PROBLEM FUNDING AND RESEARCH PERIOD
Estimated cost: $300,000 . Duration: 1.5
years.
VII – URGENCY, PAYOFF POTENTIAL, and IMPLEMENTATION
It is widely believed that existing trip generation rates data over-estimate vehicle traffic generation associated with infill, mixed-use, and transit-oriented development projects because such data is obtained in suburban areas that lack good transit or pedestrian access. This often results in excessive vehicle traffic mitigation fees, neighborhood opposition (with costly and time-consuming lawsuits), and the provision of more parking spaces and roadway pavement than actually may be needed (and which then become significant barriers for pedestrians). Another result is the under-provision of adequate pedestrian facilities, as well as insufficient transit services. These effects, in turn, result in higher development costs, delay, and even cancellation of otherwise beneficial smart growth projects, which can stall economic development, housing, and job growth within existing urban and suburban areas. By making it more costly and difficult to implement “smart growth” strategies, such effects contribute to increased traffic congestion on roads and highways, reduce the efficiency of transit service and other infrastructure, and contribute to continuing suburban sprawl.
4 It is clear that an improved and more accurate methodology for analyzing proposed land-use projects is needed.
Specifically, this project will: define quantitative relationships between vehicle travel, mode choice, and land-use characteristics in various types of urban, suburban, and rural locations; compile and apply existing up-to-date traffic, transit, and parking data from regions throughout the U.S.; and validate these quantitative land-use and travel relationships with actual trip counts and household travel surveys from various locations in the U.S. The resulting analysis tool will apply a set of six research-based mathematical “elasticities” that estimate interactions between travel demand, transportation system attributes, land-use characteristics and socioeconomic control variables. These are: Density (of housing, employment, and services), Diversity (mixed land-uses), Design (walkability and
4 Findings of the
“Statewide Transit-Oriented Development Study: Factors for Success in California,”
for
Caltrans, 2002. Available at: http://transitorienteddevelopment/miscellaneous/StatewideTOD.htm
2 of 3

connectivity), Destinations (regional accessibility), Distance from transit (light-rail, BRT, and heavyrail), and Demographics (income, age, and household size).
The analysis tool will be capable of projecting both vehicle miles and vehicle trips “generated” by proposed development projects. As vehicle miles relate to energy consumption, greenhouse gas emissions and criteria pollutant emissions, they are also key outcomes to measure at this scale.
Traditionally, traffic impact analyses estimate a proposed land-use development project’s peak hour traffic generation, since that largely determines infrastructure capacity and design requirements. In this study, researchers will derive peak hour multi-modal trip rates from survey-reported household trips by time-of-day to enable peak hour analyses. These survey responses will be validated though hour-byhour traffic counts at representative existing development sites.
VIII. PERSON DEVELOPING THE PROBLEM
Developed by: Terry Parker, MA, Senior Transportation Planner,
California Department of Transportation, Headquarters Division of Transportation Planning,
Office of Community Planning
1120 N Street, MS #32, Sacramento, CA 94274-0001
Phone: 916-654-5547. Email: Terry.Parker@dot.ca.gov
Submitted: July 10, 2008.
IX. PROBLEM MONITOR
To be determined.
X. DATE AND SUBMITTED BY
To be determined.
3 of 3