The 4 Ds
Quick-response tool for evaluating transportation effects of Smart Growth Plans, and enhancement for conventional transportation models for regional Smart Growth analysis
The literature on travel behavior substantiates that 4 “D-factors” independently affect travel behavior: land use Density, Diversity (land use mix); pedestrian Design and access to regional Destinations affect travel demand. Because these 4 Ds work at a very local level, most travel demand models are too aggregate in scale to capture the effects of the 4 Ds. A process developed by Fehr & Peers enables four-step modeling to more fully capture the effects of the 4 Ds. The process essentially modifies trip generation rates to reflect the effects of localized changes in the 4 D variables. It has been implemented as both a stand-alone spreadsheet tool, and as an optional routine in several standard four-step modeling packages (e.g., TRANSCAD, TP+ and Voyager). The heart of the 4 D methodology lies in the elasticities that are used to adjust vehicle trip rates and vehicle miles traveled. These are computed based on surveys of actual travel behavior.
PLACES
www.energy.ca.gov/places/
PLACES, an acronym for PLAnning for Community Energy, Economic and Environmental Sustainability, is an innovative software package that enables the user to quickly forecast the energy use of a given set of land uses. Users enter their land use assumptions using a GIS interface (shown at right) with drop-down menus of land use types. The program then computes the number of households and employment of various types would be in the study area. Users can then enter additional sets of land use assumptions, and produce tables comparing the scenarios in terms of vehicle trips generated in total and by household, vehicle miles of travel in total and per household, and other indicators of transportation efficiency. Fehr & Peers developed the transportation components of PLACES using survey data of the behavior of real households in different urban environments.
PLACES was developed with support from the energy offices of the states of California, Oregon, and Washington, and is designed for use by local governments. PLACES has been used for different scales of study area ranging from neighborhoods to a six-county region. Once an operator is familiar with the system they can enter data very quickly, which has enabled various governments to use PLACES in interactive public workshops.
INDEX (Criterion Planners)
GIS-based models that present plan effectiveness indicators
www.crit.com/index/index.html
INDEX is a GIS-based indicator and visualization model that analyzes and presents in a visual manner the impacts of one or more alternative planning scenarios. INDEX can evaluate plan alternatives against as many as several dozen performance indicators, e.g. density, distance to public services, farmland lost, etc. INDEX produces indicator results in numeric and map form; and produces comparative graphics for multiple case results; it also provides uniform documentation of all input parameters and assumptions. With customization, scenarios can be visualized using 3-D modeling, photography, video, and drawings. INDEX can be applied to single neighborhoods, entire communities, and multi-jurisdiction regions. Its indicator measurements can be calculated at either the parcel level or at a larger user-defined area level, such as census blocks or traffic analysis zones.
What If? (What If?, Inc.)
GIS-based model that forecasts land use based on
user-specified rules
www.what-if-pss.com
What If? is an interactive, GIS-based land use allocation model that predicts future growth patterns at a variety of scales (neighborhood to regional) for one or more specified future years based on user-specified trends and policies. Compared to complex econometric models of regional growth and land use, What If? is quite user-friendly and transparent — key assumptions affecting growth patterns are clearly apparent — and it can be used without further customization by software programmers. Data outputs from “What If?” can readily be used for further analysis both by visualization and indicator tools (e.g. INDEX) and travel demand models.
Analogue Station Analysis Techniques
Assesses the suitability of potential corridors and station sites for different modes of transit, and predicts ridership at potential stations via comparison to existing stations
Station-area population and employment levels and station transit service levels have proven to be powerful predictors of transit ridership in studies by Fehr & Peers and others. As part of a Fehr & Peers study, nearly 100 station sites in northern California and Utah were inventorieed to develop a database of station ridership data as well as station-area data on population and employment, transit service levels, park-and-ride availability and other characteristics. To evaluate the suitability ofr a proposed rail or BRT station site, analogue stations are identified on the basis of these land use and transit access characteristics, and their transit ridership patterns are examined quantitatively and qualitatively. One or more “lower ridership” and “higher ridership” analogue stations are then identified to bracket the ridership potential at the proposed station.
