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FEIS - Tahoe Regional Planning Agency

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RESPONSE TO COMMENTS ON THE DEIS<br />

B o u l d e r B a y C o m m u n i t y E n h a n c e m e n t P r o g r a m P r o j e c t E I S<br />

Fehr & Peers Mixed Use Development Model<br />

Methodology<br />

The Fehr & Peers mixed-use development model was developed using data from 239 mixed-use<br />

developments in six metropolitan regions (Boston, Atlanta, Houston, San Diego, Seattle, and<br />

Sacramento). While the data were collected in urban areas, the relationship between mixed uses<br />

can be applied to mixed-use projects in less urban areas. Hierarchical Linear Modeling (HLM)<br />

techniques were used to quantify relationships between characteristics of the mixed-use<br />

developments and the likelihood that trips generated by those mixed use developments will be<br />

made by means other than the private automobile. The mixed-use development model calculates<br />

the number of Alternative mode trips (trips made by walking, bicycling, transit, etc.) and<br />

determines the split between internal (walking between uses on the site) and external (walking,<br />

bicycling, or taking transit to a use off the site) Alternative mode trips.<br />

The Fehr & Peers mixed-use development model considers the following variables when<br />

analyzing mixed-use developments:<br />

• Employment<br />

• (Population + Employment) per square mile<br />

• Land Area<br />

• Total Jobs / Population Diversity<br />

• Retail Jobs / Population Diversity<br />

• Number of intersections per square mile<br />

• Employment within a mile<br />

• Employment within a 30-minute trip by transit<br />

• Average Household Size<br />

• Vehicles Owned Per Capita<br />

Many of these variables are examples of the "Ds", which are built environment variables that are<br />

known to influence travel behavior - density, diversity, development scale, design, and distance to<br />

transit.<br />

Validation<br />

A set of 16 independent mixed-use sites that were not included in the initial model was tested to<br />

help validate the model. The actual observed trip generation of the 16 test sites were compared to<br />

the trip generation estimated by the model. The model produced superior statistical performance<br />

when comparing the model results to observed data. Specifically, the trip generation estimated by<br />

the mixed-use development model better replicated the observed trip generation at the 16 test<br />

sites than trip generation estimated using the traditional ITE methods. For example, the statistical<br />

analysis comparing the observed trip generation to trip generation estimates from the traditional<br />

ITE methodology indicated an R-squared value of 0.58 (meaning the methodology explains about<br />

58 percent of the variability in trips). The statistical analysis comparing the observed trip<br />

generation to trip generation estimates using the mixed-use model indicated an R-squared value<br />

of 0.82 (meaning the methodology explains 82 percent of the trips).<br />

The mixed-use development model has been developed in cooperation with the US<br />

Environmental Protection <strong>Agency</strong> (EPA) and ITE. ITE is currently reviewing the model for<br />

potential inclusion in their updated recommended practice for evaluating mixed-use development<br />

SEPTEMBER 8 , 2010 HAUGE BRUECK ASSOCIATES PAGE 8- 19

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